I have experimented with aluminum casting with the 12 quart forge twice now. Both times I ran into problems.
This forge is suitable for melting aluminum, perhaps more suitable than it is for forging iron. Even with regular charcoal fuel (not pellets), it gets hot enough to melt aluminum fairly quickly. The problem is containing the molten metal. Many sources online suggest cast iron, which works very well. The problem is that it is difficult to find cast iron in any form other than skillets. So, the first time I did this, I used a small cast iron skillet. Unfortunately, it gets too hot to hold the handle. So, I put a piece of rebar through the hold in the handle, and used that to hold it. This was not very stable, and in the end, it spilled around half a cup of liquid aluminum in the forge. As expected, this ruined the forge and required severe damage to the refractory to remove. I eventually repaired the forge. The next try, I used a stainless steel cup from a thrift store. I put holes through the top rim and put bolts in it, to support the cup over the forge and to give my tongs a place to grab the cup. Unfortunately, the stainless steel corroded through after around 30 minutes. As before, molten metal spilled in the forge and now it is broken again. A nearby hardware store is selling a cast iron pot that is around 8 inches in diameter. Once I have enough money, I plan on buying one and using it. That should handle the heat better than the cup and be more stable than the skillet.
Besides the two disasters, I learned some other things about casting aluminum. First, a mini muffin tin makes a really good ingot mold for aluminum. I now have somewhere around 12 mini muffin shaped aluminum ingots. The second time around, I also tried to make 3 castings. These mostly failed. I learned some things. First, you cannot cast aluminum in open top molds. This allows it to cool to quickly, which causes warping due to shrinkage of the metal as it cools. Instead, the mold should have sprues (tubes) that extend up from the casting. The metal is poured into these sprues until both the casting mold and the sprues are filled. If the sprues are large enough, then they will provide additional metal to the casting as it shrinks, eliminating warping. The molten metal in the sprues will also help the casting cool more slowly, which will result in a higher quality casting. These are well known metal casting techniques (which I was already familiar with). Laziness in metal casting does not pay.
I will post more on this once I have time to repair the forge again. I am considering building a dedicated smelter. These can be designed to be spill tolerant. If I do this, I will be using propane to fuel it, instead of charcoal.
Lord Rybec
Friday, March 1, 2013
Thursday, February 28, 2013
Sulfurless Black Powder
In my last post, 2 years ago, I said I might write about this. Since it has been so long, I feel like I owe it to you to make good on that threat.
First, I have only ever read about this technique for making black powder in one place (I no longer recall the source). This is superior to any other technique I know of, and supposedly it was used around Civil War times for making the highest grades of military gunpowder. I will describe the use of this process for making sulfurless black powder, because this is what I make with it. The original purpose of the sulfur in black powder was to make it ignite easily with a spark. I am using this for rocketry, where I don't need it to ignite so easily, so there is no reason that I need the sulfur. In addition, sulfur is the most expensive and difficult to obtain ingredient, and leaving it out makes the gunpowder less volatile and thus much safer to handle. The side effect is that the rockets are extremely difficult to ignite without commercial rocket igniters (like the ones that come with Estes rocket engines).
To begin, we need our ingredients. Traditional black powder is made from charcoal, saltpetre (potassium nitrate), and sulfur. As we are leaving out the sulfur, we only need the charcoal and potassium nitrate. Now, note that we cannot just use a bag of charcoal briquettes from the store. These typically contain bits of unburnt wood and some oils to make them light more easily. These will ruin the gunpowder. In one of my earlier posts, I explained how to make charcoal, but I will briefly go over it again.
Charcoal is made by burning wood without oxygen. This is easily done by placing pieces of wood in a metal container that is not quite air tight, and then placing this in a very hot fire for a while. As the container heats up, it will vent volatile gasses (which will ignite if they are near the flames). Once these gasses have stopped venting entirely, the charcoal is probably done.
The potassium nitrate may be more difficult to find. I actually had great difficulty finding it initially. One likely place to find it is a store that sells meat processing supplies, as it was traditionally used to cure meat. Many of these places sell more modern curing chemicals though, instead of potassium nitrate. Conveniently though, it turns out that the powdered stump remover sold in most hardware stores is typically pure potassium nitrate. Before buying it though, ask for an MSDS for it. This will list the ingredients. Some stump removers have one or two additional chemicals which happen to be poisonous and which would probably produce toxic smoke when burned. Only use it for gunpowder if the only ingredient listed is potassium nitrate (I use Spectracide, but I would recommend getting the MSDS even if you do get this brand, just to be safe).
Now, you need to grind the charcoal to be incredibly fine. I don't know how fine they got it for traditional gunpowder, but the finer you get it, the more efficiently it will burn and the more power you will get out of it. The best way to do this is with a ball mill. Since most people do not have easy access to this kind of equipment, I will tell you how to make your own. Buy a small rock tumbler (don't get one of those tiny plastic ones that comes with those cheap educational kit though; get a 3 lb. one at least). Also buy a couple packs of glass marbles. If there are any marbles with unusual surface textures, remove those, as they could break (I also removed some cool looking ones that I wanted to keep). From the rest, measure out around 2 lbs. (if your tumbler is bigger than 3 lbs. adjust this accordingly; don't put in more than 2/3 the maximum weight of the tumbler). These marbles will be the balls for your makeshift ball mill. Place these in the drum of the tumbler, and then fill it the rest of the way with charcoal (it works best if the charcoal is already crushed up a bit). It might be a good idea to check the weight at this point, to make sure you are not exceeding the maximum weight. If you are, remove some charcoal and/or some marbles. Now, run the rock tumbler for a while. The time required will depend on the size of the tumbler and the hardness of the charcoal. I used fir for the charcoal (supposedly hardwoods are better) and it took only a day before most of the charcoal was an extremely fine powder. Next time, I will probably run it for two days, because there were still a few small chunks left (though, running this through a fine sieve would easily remove those).
You will need a third ingredient. Get some of the highest percentage rubbing alcohol you can find. I used 97%, but I have only seen it a few times. Make sure you get enough. I don't know exactly how much this is, but one cup of gunpowder needs more than a 1 pint bottle of alcohol. Put the alcohol in the freezer the night before you want to make the gunpowder.
Once the charcoal is finely powdered (mine was finer than powdered sugar), you are ready to make the black powder. According to Wikipedia on sulfurless black powder, "They typically contain 70.5 parts of saltpetre and 29.5 parts of charcoal." This should be by weight. Measure out the amounts of each that you need before starting. According to the Wikipedia page on potassium nitrate, the saturation point of potassium nitrate in water at boiling is 2460 g/L. This is 2460 grams of potassium nitrate for each liter of water. Since you are probably not using grams and liters, use Google to convert the units for you (entering "2460 g/L to oz/gallon" gives you "328.475119 oz / US gallon"). Use this to figure out how much water you need, then add few extra tablespoons to that. Put the water in a pan, add the potassium nitrate, then heat the water to boiling. If you did your math right, once the water gets close to boiling, all of the potassium nitrate will have dissolved. Now, let it boil and watch it carefully. When potassium nitrate crystals start to appear in the water (not just at the edges), pour all of the charcoal powder in and stir it in. Right before you do this, take the alcohol out of the freezer and pour it all into a large bowl (it needs to fit all of the gunpowder in there as well). My charcoal did not want to mix in well. If this happens, just keep stirring until it does. Leave the burner on while you do this (don't worry, the gun powder will not ignite; besides the fact that it is wet, without the sulfur, it is extremely difficult to ignite, even with an open flame). Once the mixture has turned into a black paste, with all of the charcoal mixed in, turn off the burner, and pour the mixture into the chilled alcohol. This is the part I always have problems with. The first time I did it, it went fine, but the second time, I did not have enough alcohol, and I poured the powder too fast. For this to work properly, the alcohol needs to remain chilled (if you don't have enough, the hot mixture will warm it up). Also, if you pour too fast, you will end up with a pile of the mixture at the bottom, where the middle is insulated from the cold by the outside. The fast cooling is essential for optimum quality.
Leave the mixture in the alcohol until it has cooled completely. It should now be fairly solid, though easy to break. Pour the alcohol off and save it (you can reuse the alcohol several times, even if it is dirty from the previous batch). Break up the chunks of black powder (don't crush them into fine powder though), and place them somewhere they can finish drying. In a warm climate this should only take a day (give it more time in a cold climate). I don't know how long it will take in a humid climate.
Once it is dry, you can pack it into rocket tubes to make engines. This powder will not make a good explosive, and don't bother trying to use it in an old gun. The lack of sulfur makes it so difficult to light that even an open flame may take half a minute to light it. Really, it is not very good for anything but confined burns like in model rocket engines. Given that this process was originally used for making powder intended for guns, it would probably work fine for a more traditional gunpowder mixture that includes sulfur.
Now, I want to talk about why this produces such high quality black powder. Black powder is a oxidizer/fuel mixture. The charcoal is the fuel and the potassium nitrate is the oxidizer. The efficiency of the powder depends on how well the burning charcoal can get the oxygen from the potassium nitrate. Two things will improve this. First, the smaller the particles, the more surface area they have and the better the oxygen can transfer. Second, the more intimately the ingredients are mixed, the better oxygen can be transferred. Milling the charcoal with the ball mill will get those particles very small. We could stop there and mill the potassium nitrate in with the charcoal (this is the common way most rocket enthusiasts make black powder now). Potassium nitrate dissolves in water though, which gives us another option. What we did above was to supersaturate the water with potassium nitrate. This means that we increased the amount of potassium nitrate that the water could hold by heating the water, then we dissolved the maximum amount in it. As the water cools, the potassium nitrate will start to crystallize out. The faster the water cools, the smaller the crystals will be. In addition, crystals tend to form first around rough spots. The charcoal is very porous and thus has an enormous amount of rough spots. So, when we poured the mixture into the chilled alcohol, the potassium nitrate formed extremely small (microscopic) crystals all over the rough charcoal particles. This is about the most intimate mixture you can get without rearranging individual molecules. This means that the mixture will burn almost completely (coarser mixtures will have a lot of partially burned particles), which means we maximize the energy output. This creates an extremely efficient rocket fuel when we use it to make sulfurless black powder.
I hope this is useful to someone. Like I said, I have only seen this technique described once. I have not been able to find any information about it since. Because I know the chemistry behind it, I know that it works. By publishing this information, I may be preventing this from becoming a lost art.
Lord Rybec
First, I have only ever read about this technique for making black powder in one place (I no longer recall the source). This is superior to any other technique I know of, and supposedly it was used around Civil War times for making the highest grades of military gunpowder. I will describe the use of this process for making sulfurless black powder, because this is what I make with it. The original purpose of the sulfur in black powder was to make it ignite easily with a spark. I am using this for rocketry, where I don't need it to ignite so easily, so there is no reason that I need the sulfur. In addition, sulfur is the most expensive and difficult to obtain ingredient, and leaving it out makes the gunpowder less volatile and thus much safer to handle. The side effect is that the rockets are extremely difficult to ignite without commercial rocket igniters (like the ones that come with Estes rocket engines).
To begin, we need our ingredients. Traditional black powder is made from charcoal, saltpetre (potassium nitrate), and sulfur. As we are leaving out the sulfur, we only need the charcoal and potassium nitrate. Now, note that we cannot just use a bag of charcoal briquettes from the store. These typically contain bits of unburnt wood and some oils to make them light more easily. These will ruin the gunpowder. In one of my earlier posts, I explained how to make charcoal, but I will briefly go over it again.
Charcoal is made by burning wood without oxygen. This is easily done by placing pieces of wood in a metal container that is not quite air tight, and then placing this in a very hot fire for a while. As the container heats up, it will vent volatile gasses (which will ignite if they are near the flames). Once these gasses have stopped venting entirely, the charcoal is probably done.
The potassium nitrate may be more difficult to find. I actually had great difficulty finding it initially. One likely place to find it is a store that sells meat processing supplies, as it was traditionally used to cure meat. Many of these places sell more modern curing chemicals though, instead of potassium nitrate. Conveniently though, it turns out that the powdered stump remover sold in most hardware stores is typically pure potassium nitrate. Before buying it though, ask for an MSDS for it. This will list the ingredients. Some stump removers have one or two additional chemicals which happen to be poisonous and which would probably produce toxic smoke when burned. Only use it for gunpowder if the only ingredient listed is potassium nitrate (I use Spectracide, but I would recommend getting the MSDS even if you do get this brand, just to be safe).
Now, you need to grind the charcoal to be incredibly fine. I don't know how fine they got it for traditional gunpowder, but the finer you get it, the more efficiently it will burn and the more power you will get out of it. The best way to do this is with a ball mill. Since most people do not have easy access to this kind of equipment, I will tell you how to make your own. Buy a small rock tumbler (don't get one of those tiny plastic ones that comes with those cheap educational kit though; get a 3 lb. one at least). Also buy a couple packs of glass marbles. If there are any marbles with unusual surface textures, remove those, as they could break (I also removed some cool looking ones that I wanted to keep). From the rest, measure out around 2 lbs. (if your tumbler is bigger than 3 lbs. adjust this accordingly; don't put in more than 2/3 the maximum weight of the tumbler). These marbles will be the balls for your makeshift ball mill. Place these in the drum of the tumbler, and then fill it the rest of the way with charcoal (it works best if the charcoal is already crushed up a bit). It might be a good idea to check the weight at this point, to make sure you are not exceeding the maximum weight. If you are, remove some charcoal and/or some marbles. Now, run the rock tumbler for a while. The time required will depend on the size of the tumbler and the hardness of the charcoal. I used fir for the charcoal (supposedly hardwoods are better) and it took only a day before most of the charcoal was an extremely fine powder. Next time, I will probably run it for two days, because there were still a few small chunks left (though, running this through a fine sieve would easily remove those).
You will need a third ingredient. Get some of the highest percentage rubbing alcohol you can find. I used 97%, but I have only seen it a few times. Make sure you get enough. I don't know exactly how much this is, but one cup of gunpowder needs more than a 1 pint bottle of alcohol. Put the alcohol in the freezer the night before you want to make the gunpowder.
Once the charcoal is finely powdered (mine was finer than powdered sugar), you are ready to make the black powder. According to Wikipedia on sulfurless black powder, "They typically contain 70.5 parts of saltpetre and 29.5 parts of charcoal." This should be by weight. Measure out the amounts of each that you need before starting. According to the Wikipedia page on potassium nitrate, the saturation point of potassium nitrate in water at boiling is 2460 g/L. This is 2460 grams of potassium nitrate for each liter of water. Since you are probably not using grams and liters, use Google to convert the units for you (entering "2460 g/L to oz/gallon" gives you "328.475119 oz / US gallon"). Use this to figure out how much water you need, then add few extra tablespoons to that. Put the water in a pan, add the potassium nitrate, then heat the water to boiling. If you did your math right, once the water gets close to boiling, all of the potassium nitrate will have dissolved. Now, let it boil and watch it carefully. When potassium nitrate crystals start to appear in the water (not just at the edges), pour all of the charcoal powder in and stir it in. Right before you do this, take the alcohol out of the freezer and pour it all into a large bowl (it needs to fit all of the gunpowder in there as well). My charcoal did not want to mix in well. If this happens, just keep stirring until it does. Leave the burner on while you do this (don't worry, the gun powder will not ignite; besides the fact that it is wet, without the sulfur, it is extremely difficult to ignite, even with an open flame). Once the mixture has turned into a black paste, with all of the charcoal mixed in, turn off the burner, and pour the mixture into the chilled alcohol. This is the part I always have problems with. The first time I did it, it went fine, but the second time, I did not have enough alcohol, and I poured the powder too fast. For this to work properly, the alcohol needs to remain chilled (if you don't have enough, the hot mixture will warm it up). Also, if you pour too fast, you will end up with a pile of the mixture at the bottom, where the middle is insulated from the cold by the outside. The fast cooling is essential for optimum quality.
Leave the mixture in the alcohol until it has cooled completely. It should now be fairly solid, though easy to break. Pour the alcohol off and save it (you can reuse the alcohol several times, even if it is dirty from the previous batch). Break up the chunks of black powder (don't crush them into fine powder though), and place them somewhere they can finish drying. In a warm climate this should only take a day (give it more time in a cold climate). I don't know how long it will take in a humid climate.
Once it is dry, you can pack it into rocket tubes to make engines. This powder will not make a good explosive, and don't bother trying to use it in an old gun. The lack of sulfur makes it so difficult to light that even an open flame may take half a minute to light it. Really, it is not very good for anything but confined burns like in model rocket engines. Given that this process was originally used for making powder intended for guns, it would probably work fine for a more traditional gunpowder mixture that includes sulfur.
Now, I want to talk about why this produces such high quality black powder. Black powder is a oxidizer/fuel mixture. The charcoal is the fuel and the potassium nitrate is the oxidizer. The efficiency of the powder depends on how well the burning charcoal can get the oxygen from the potassium nitrate. Two things will improve this. First, the smaller the particles, the more surface area they have and the better the oxygen can transfer. Second, the more intimately the ingredients are mixed, the better oxygen can be transferred. Milling the charcoal with the ball mill will get those particles very small. We could stop there and mill the potassium nitrate in with the charcoal (this is the common way most rocket enthusiasts make black powder now). Potassium nitrate dissolves in water though, which gives us another option. What we did above was to supersaturate the water with potassium nitrate. This means that we increased the amount of potassium nitrate that the water could hold by heating the water, then we dissolved the maximum amount in it. As the water cools, the potassium nitrate will start to crystallize out. The faster the water cools, the smaller the crystals will be. In addition, crystals tend to form first around rough spots. The charcoal is very porous and thus has an enormous amount of rough spots. So, when we poured the mixture into the chilled alcohol, the potassium nitrate formed extremely small (microscopic) crystals all over the rough charcoal particles. This is about the most intimate mixture you can get without rearranging individual molecules. This means that the mixture will burn almost completely (coarser mixtures will have a lot of partially burned particles), which means we maximize the energy output. This creates an extremely efficient rocket fuel when we use it to make sulfurless black powder.
I hope this is useful to someone. Like I said, I have only seen this technique described once. I have not been able to find any information about it since. Because I know the chemistry behind it, I know that it works. By publishing this information, I may be preventing this from becoming a lost art.
Lord Rybec
Sunday, May 1, 2011
Turmeric Ink
Interesting experiment I did yesterday, though probably not one that will end up in my book. It is interesting enough that I thought I should write about it here though.
I don't know if I have mentioned it yet, but one of the subjects that will be in my book is soap making. This requires lye. My problem was that I need some means of measuring the concentration of lye in solution. So, I started looking up how to make acid/base indicators. On a page I found on a totally unrelated subject, they had a note at the end pointing out that turmeric turns red when exposed to a base. It did not take long before I knew a whole lot about curcumin, the chemical in turmeric that gives it the yellow color (and that turns red in a base).
So, it turns out that this chemical is not water soluble (or at least, not significantly), but it is soluble in alcohol. I happened to have some 91% rubbing alcohol (for making black powder, which I may write about in the future) around, so I put some turmeric in a small cup of the rubbing alcohol. The liquid turned yellow (ie, clear yellow, after the turmeric powder settled to the bottom). I messed around with this solution by mixing a bit with some baking soda, and also with some of the lye that I made for making soap. It turned pretty dark red.
So, next I made a larger batch and soaked some small squares of paper it in, to make indicator strips. I set the paper squares on some wax paper to dry and then decided to play with the leftovers. I poured just a little bit of lye into the white ceramic container that the solution was in, and the liquid turned blood red, literally (it was actually mildly disconcerting).
Well, I wanted to see how it would handle on paper, as ink (you know the whole "signed in blood" thing). Well, I discovered that this red solution bleeds out on the paper quite quickly (due to the alcohol). Not all of the solution had turned red, but since both parts were mixed, the yellow portion was not obvious. When the solution bleed out into the paper though, the yellow flowed better, thus the red spot had a yellow "halo" around it (I suspect the water in the lye solution made the red flow through the paper slower than the yellow part that was mostly in alcohol). Also, over time the red spot turned mostly yellow. Now, it is possible that this is partially because the lye concentration was reduced as it was absorbed into the paper. However, the largest effect comes from acid in the paper partially or entirely neutralizing the lye. Experiments with acid free paper actually confirmed both of these. The red ink immediately becomes orange, telling me that the affect on lye concentration had some effect, but it did not turn entirely yellow (or become more yellow over time), telling me that the acid in the other paper was also playing a large part. My solution to this will be to add stronger lye to make more of the ink red and to counter the dilution of the lye as it soaks into the paper (the lye is in a water solution, so I don't want to add enough to affect the solubility of the chemical, so stronger lye means more base with less water). First though, I will have to evaporate down my lye to increase the concentration.
Ok, so next I wondered how easy this would be to use in a printer cartridge. I had a black cartridge that had recently run out, as well as a replacement waiting to be installed, so I figured that if it damaged the cartridge, it would be no great loss. So, I cleaned out the cartridge (with water, since the HP black ink is not alcohol soluble, but is water soluble) and refilled it with another batch of the ink (carefully strained so that the turmeric particles would not block the jets). Besides the fact that my homemade plug is not very good, so air leaks into the cartridge, causing smearing from too high of ink flow, it actually worked pretty well. Ironically, printing from my Windows XP computer uses color ink for gray-scale, even when set for black only, so gray-scale gradients did not use the cartridge properly, but my Linux computer worked perfectly when set to use black only.
There are a lot of cool uses for this ink. If you got the concentration right, it would probably make a fine replacement for yellow printer ink (assuming your prints would not be exposed to alkaline environments). A better application though, is security. First, if you put a basic solution on the print, this ink will turn red (or pink, if the ink volume is not very high). Acid will turn it back yellow. Second, evidently, this chemical fluoresces under black light. Printed at a low volume, you could essentially use this ink to make security "watermarks" that could be authenticated using a black light and simple chemical tests. I have also seen suggestions for using this as highlighter ink, which would probably work extremely well at the right concentration.
Since most of the above applications are not currently important to me, what I have now is a cartridge that allows me to print acid/base indicator paper which I can cut into strips for use in my experiments. (This is actually pretty cool, since the printer should be able to always get the same ink volume, once I fix my plug, and also uses a lot less solution per strip.)
A big note here: This stuff is messy. There are few things that it will not stain (it did not stain the ceramic sink, but other smooth surfaces did stain). Since it is not water soluble, it will only wash off extremely smooth surfaces (and, with a lot of pressure and the rough side of the dish washing pad). You can soak your sponge or rag with alcohol and it will wash off most smooth surfaces this way, but may still leave light stains. If the stains are slightly orange to red, you can wash with vinegar to turn it yellow (less visible), but exposure to a base should turn it red. Oh, and I would not expect this to wash out of clothes easily. And, if you do the printer thing, if the jets clog when you don't use it for a while, try cleaning with alcohol, since water will not help much.
I do not know the long term effects of using an alcohol based ink in inkjet cartridges. Also, since I did this yesterday, I don't know if this ink will decay or discolor over time. As of now, this is extremely experimental.
Lord Rybec
I don't know if I have mentioned it yet, but one of the subjects that will be in my book is soap making. This requires lye. My problem was that I need some means of measuring the concentration of lye in solution. So, I started looking up how to make acid/base indicators. On a page I found on a totally unrelated subject, they had a note at the end pointing out that turmeric turns red when exposed to a base. It did not take long before I knew a whole lot about curcumin, the chemical in turmeric that gives it the yellow color (and that turns red in a base).
So, it turns out that this chemical is not water soluble (or at least, not significantly), but it is soluble in alcohol. I happened to have some 91% rubbing alcohol (for making black powder, which I may write about in the future) around, so I put some turmeric in a small cup of the rubbing alcohol. The liquid turned yellow (ie, clear yellow, after the turmeric powder settled to the bottom). I messed around with this solution by mixing a bit with some baking soda, and also with some of the lye that I made for making soap. It turned pretty dark red.
So, next I made a larger batch and soaked some small squares of paper it in, to make indicator strips. I set the paper squares on some wax paper to dry and then decided to play with the leftovers. I poured just a little bit of lye into the white ceramic container that the solution was in, and the liquid turned blood red, literally (it was actually mildly disconcerting).
Well, I wanted to see how it would handle on paper, as ink (you know the whole "signed in blood" thing). Well, I discovered that this red solution bleeds out on the paper quite quickly (due to the alcohol). Not all of the solution had turned red, but since both parts were mixed, the yellow portion was not obvious. When the solution bleed out into the paper though, the yellow flowed better, thus the red spot had a yellow "halo" around it (I suspect the water in the lye solution made the red flow through the paper slower than the yellow part that was mostly in alcohol). Also, over time the red spot turned mostly yellow. Now, it is possible that this is partially because the lye concentration was reduced as it was absorbed into the paper. However, the largest effect comes from acid in the paper partially or entirely neutralizing the lye. Experiments with acid free paper actually confirmed both of these. The red ink immediately becomes orange, telling me that the affect on lye concentration had some effect, but it did not turn entirely yellow (or become more yellow over time), telling me that the acid in the other paper was also playing a large part. My solution to this will be to add stronger lye to make more of the ink red and to counter the dilution of the lye as it soaks into the paper (the lye is in a water solution, so I don't want to add enough to affect the solubility of the chemical, so stronger lye means more base with less water). First though, I will have to evaporate down my lye to increase the concentration.
Ok, so next I wondered how easy this would be to use in a printer cartridge. I had a black cartridge that had recently run out, as well as a replacement waiting to be installed, so I figured that if it damaged the cartridge, it would be no great loss. So, I cleaned out the cartridge (with water, since the HP black ink is not alcohol soluble, but is water soluble) and refilled it with another batch of the ink (carefully strained so that the turmeric particles would not block the jets). Besides the fact that my homemade plug is not very good, so air leaks into the cartridge, causing smearing from too high of ink flow, it actually worked pretty well. Ironically, printing from my Windows XP computer uses color ink for gray-scale, even when set for black only, so gray-scale gradients did not use the cartridge properly, but my Linux computer worked perfectly when set to use black only.
There are a lot of cool uses for this ink. If you got the concentration right, it would probably make a fine replacement for yellow printer ink (assuming your prints would not be exposed to alkaline environments). A better application though, is security. First, if you put a basic solution on the print, this ink will turn red (or pink, if the ink volume is not very high). Acid will turn it back yellow. Second, evidently, this chemical fluoresces under black light. Printed at a low volume, you could essentially use this ink to make security "watermarks" that could be authenticated using a black light and simple chemical tests. I have also seen suggestions for using this as highlighter ink, which would probably work extremely well at the right concentration.
Since most of the above applications are not currently important to me, what I have now is a cartridge that allows me to print acid/base indicator paper which I can cut into strips for use in my experiments. (This is actually pretty cool, since the printer should be able to always get the same ink volume, once I fix my plug, and also uses a lot less solution per strip.)
A big note here: This stuff is messy. There are few things that it will not stain (it did not stain the ceramic sink, but other smooth surfaces did stain). Since it is not water soluble, it will only wash off extremely smooth surfaces (and, with a lot of pressure and the rough side of the dish washing pad). You can soak your sponge or rag with alcohol and it will wash off most smooth surfaces this way, but may still leave light stains. If the stains are slightly orange to red, you can wash with vinegar to turn it yellow (less visible), but exposure to a base should turn it red. Oh, and I would not expect this to wash out of clothes easily. And, if you do the printer thing, if the jets clog when you don't use it for a while, try cleaning with alcohol, since water will not help much.
I do not know the long term effects of using an alcohol based ink in inkjet cartridges. Also, since I did this yesterday, I don't know if this ink will decay or discolor over time. As of now, this is extremely experimental.
Lord Rybec
Publish Post
Friday, April 22, 2011
Plastics, continued
I've managed to do a lot more work and gather a lot more information on plastics since my last post. Here is what I have learned:
The ideal method for making the casein (milk protein) plastic uses 2% milk. 1% works also, but may require some blending to get the majority of it dissolved. Just heat the milk to simmering and then add some vinegar. I forget the exact amount, but if you don't add enough to totally separate it within one minute, just add a little more (see my previous post on plastics for ideal measurements).
If you do not add some baking soda to dissolve it a little bit (don't add too much, or you get glue; again, fairly exact measurements should be in the previous plastics post), it will be very difficult to mold. Once the stuff is dissolved into a very thick goo, you can let it sit for a bit to make it less sticky (this also allows the vinegar/baking soda reaction to finish). I found that it is easiest to work with if you let it sit for around 10 minutes (in a humid climate, it might need more), then work it with wet hands. You should definitely knead it, to get the bubbles produced by the vinegar/baking soda reaction out (bubbles will weaken it). Since it tends to warp a lot when drying, the best use is to make a flat sheet of plastic (put weight on it while drying, but make sure it gets enough air for it to dry; good luck). At 1-1.5mm thick it is brittle enough to break easily, but strong enough to use as a guitar pick (I am not good enough to "rock out", so it may not handle more active playing). At .5cm thick, it is still brittle, but much harder to break. Much thicker takes a very long time to dry (I have a piece that is almost 1cm thick that is still not dry after 5 days). If you prevent the surface from drying for too long, it can mold (I was cycling between weight that restricted air access with open air drying with no weight), but it can easily be sanded off once it is dry.
Casein plastic is extremely easy to shape and cut with a Dremel tool. It is reasonable to assume that it could be shaped with a CNC grinding machine. With a Dremel, you can etch artwork into the surface of the pieces.
If you have a good coffee grinder (that you do not intend on using for coffee ever again), you can grind cardboard into a fluffy powdery substance (similar in texture to cellulose insulation; also, avoid breathing the dust). If you mix this with the plastic before shaping and drying it, it will be many times stronger and far less brittle. You will need to add some water when mixing, but only add as much as you need to keep it moldable (otherwise it will take too long to dry). You will need to add quite a bit of the ground paper fiber to get the strength indicated above, but even a little should make a difference. (I used cardboard from cereal boxes. It was a little lumpy, but worked fine. I also happen to know that corrugated cardboard grinds really well.) Using longer cellulose fibers should work even better (things like cotton or hemp should perform far better than the paper fiber).
Note that adding the baking soda makes this plastic mildly water soluble. You can fix this by soaking it in vinegar for a few minutes, after it is dry (you might be able to do this wet as well, but I have not tried it). Don't leave the paper plastic composite in vinegar for too long, because the paper wicks the vinegar in deep, and bubbles will form within the plastic from the reaction. After this, you have to let it dry again (a few hours or so). This makes it water resistant. More than a few minutes exposure to water will still soften the plastic (and it will probably warp while drying), but it will not make the surface slimy or make the plastic dissolve.
I also tried making plastic from wheat gluten (yes, that is the thing that some people are allergic too; I am not sure how exposure to the skin would affect someone with such and allergy, so be careful if you are one of those people). I extracted the gluten manually. First, I mixed white (not bleached) flour with water (you can use whole wheat flour, but it takes longer as there is more fiber to get out). You want enough flour that you end up with a thick doughy mixture. It should not be significantly sticky (if it is, keep kneading in more flour until it is not). Once it is kneaded out well, make a ball and put it into a bowl of water that entirely covers the ball of dough. You can refrigerate this, but you do not have to. After several hours, you begin kneading it again, in the water this time. You will notice the water turns milky (this is wheat starch and other non-gluten wheat products). The surface will start to become loose pieces that are slightly sticky and extremely stretchy. This is the gluten. It sticks to itself well, so if pieces come off, just stick them back on. When the water becomes really white, dump it out (you can actually collect this and evaporate the water to get wheat starch) and put new water in (or, if you have a fairly large bowl, you can run the water while kneading). Eventually, the ball will no longer make the water white when kneaded or squeezed hard. At this point, you have fairly pure gluten. This gluten can be kneaded into a ball and then flattened and dried. It tends to shrink a lot when drying and thus warps a lot like casein, and so should be treated similarly when drying. This should work with reconstituted gluten powder that can be bought at the store, but I have not tried it yet.
A good note here is that gluten reacts oppositely to ph levels as casein. In other words, if you soak it in a little vinegar, it will dissolve, while a base (like baking soda) will return it to the rubbery insoluble that it started as. I have a few experimental applications for this property that I will discuss in a future post.
This plastic is also fairly hard, but brittle. I have not tried making a piece thicker than 1.5mm, but that thin piece worked fine as a guitar pick. The color is translucent, dark brown, as opposed to the opaque ivory color of casein. The gluten plastic also held a lot of air bubbles. I don't know if these are removable without the use of a vacuum jar or similar vacuum device. This plastic is naturally water resistant, but like the vinegar processed casein, it will still become soft with more than brief exposure to water. It is also easily workable with a Dremel, or similar rotary tool.
My next experiment with plastic is a fairly common bioplastic (the above are also technically bioplastics, though you would probably not find them on a list). It is made from starch, vinegar, and glycerin. The vinegar breaks down the part of the starch that is not a good polymer, so that it can become a good polymer. The glycerine makes if flexible. The amount of glycerine determines the flexibility, so a harder plastic can be made with less, or a more flexible with more. See: http://www.instructables.com/id/Make-Potato-Plastic!/ Note that this is a good application for the starch removed from the wheat gluten.
Starch is easy to obtain, as is vinegar. Glycerin is a bit harder to find. So I have gone to efforts to determine how to make it. In short, you make lye from wood ashes. With lye, fat/oil, and salt, you make soap. The byproduct is glycerin (which is sometimes mixed into the soap, but not for this application). An interesting note is that if you add the right amount of methanol to the lye, you will get biodiesel instead of soap, still with a by product of glycerin. So, instructions for making biodiesel will be in my book as well.
Lord Rybec
The ideal method for making the casein (milk protein) plastic uses 2% milk. 1% works also, but may require some blending to get the majority of it dissolved. Just heat the milk to simmering and then add some vinegar. I forget the exact amount, but if you don't add enough to totally separate it within one minute, just add a little more (see my previous post on plastics for ideal measurements).
If you do not add some baking soda to dissolve it a little bit (don't add too much, or you get glue; again, fairly exact measurements should be in the previous plastics post), it will be very difficult to mold. Once the stuff is dissolved into a very thick goo, you can let it sit for a bit to make it less sticky (this also allows the vinegar/baking soda reaction to finish). I found that it is easiest to work with if you let it sit for around 10 minutes (in a humid climate, it might need more), then work it with wet hands. You should definitely knead it, to get the bubbles produced by the vinegar/baking soda reaction out (bubbles will weaken it). Since it tends to warp a lot when drying, the best use is to make a flat sheet of plastic (put weight on it while drying, but make sure it gets enough air for it to dry; good luck). At 1-1.5mm thick it is brittle enough to break easily, but strong enough to use as a guitar pick (I am not good enough to "rock out", so it may not handle more active playing). At .5cm thick, it is still brittle, but much harder to break. Much thicker takes a very long time to dry (I have a piece that is almost 1cm thick that is still not dry after 5 days). If you prevent the surface from drying for too long, it can mold (I was cycling between weight that restricted air access with open air drying with no weight), but it can easily be sanded off once it is dry.
Casein plastic is extremely easy to shape and cut with a Dremel tool. It is reasonable to assume that it could be shaped with a CNC grinding machine. With a Dremel, you can etch artwork into the surface of the pieces.
If you have a good coffee grinder (that you do not intend on using for coffee ever again), you can grind cardboard into a fluffy powdery substance (similar in texture to cellulose insulation; also, avoid breathing the dust). If you mix this with the plastic before shaping and drying it, it will be many times stronger and far less brittle. You will need to add some water when mixing, but only add as much as you need to keep it moldable (otherwise it will take too long to dry). You will need to add quite a bit of the ground paper fiber to get the strength indicated above, but even a little should make a difference. (I used cardboard from cereal boxes. It was a little lumpy, but worked fine. I also happen to know that corrugated cardboard grinds really well.) Using longer cellulose fibers should work even better (things like cotton or hemp should perform far better than the paper fiber).
Note that adding the baking soda makes this plastic mildly water soluble. You can fix this by soaking it in vinegar for a few minutes, after it is dry (you might be able to do this wet as well, but I have not tried it). Don't leave the paper plastic composite in vinegar for too long, because the paper wicks the vinegar in deep, and bubbles will form within the plastic from the reaction. After this, you have to let it dry again (a few hours or so). This makes it water resistant. More than a few minutes exposure to water will still soften the plastic (and it will probably warp while drying), but it will not make the surface slimy or make the plastic dissolve.
I also tried making plastic from wheat gluten (yes, that is the thing that some people are allergic too; I am not sure how exposure to the skin would affect someone with such and allergy, so be careful if you are one of those people). I extracted the gluten manually. First, I mixed white (not bleached) flour with water (you can use whole wheat flour, but it takes longer as there is more fiber to get out). You want enough flour that you end up with a thick doughy mixture. It should not be significantly sticky (if it is, keep kneading in more flour until it is not). Once it is kneaded out well, make a ball and put it into a bowl of water that entirely covers the ball of dough. You can refrigerate this, but you do not have to. After several hours, you begin kneading it again, in the water this time. You will notice the water turns milky (this is wheat starch and other non-gluten wheat products). The surface will start to become loose pieces that are slightly sticky and extremely stretchy. This is the gluten. It sticks to itself well, so if pieces come off, just stick them back on. When the water becomes really white, dump it out (you can actually collect this and evaporate the water to get wheat starch) and put new water in (or, if you have a fairly large bowl, you can run the water while kneading). Eventually, the ball will no longer make the water white when kneaded or squeezed hard. At this point, you have fairly pure gluten. This gluten can be kneaded into a ball and then flattened and dried. It tends to shrink a lot when drying and thus warps a lot like casein, and so should be treated similarly when drying. This should work with reconstituted gluten powder that can be bought at the store, but I have not tried it yet.
A good note here is that gluten reacts oppositely to ph levels as casein. In other words, if you soak it in a little vinegar, it will dissolve, while a base (like baking soda) will return it to the rubbery insoluble that it started as. I have a few experimental applications for this property that I will discuss in a future post.
This plastic is also fairly hard, but brittle. I have not tried making a piece thicker than 1.5mm, but that thin piece worked fine as a guitar pick. The color is translucent, dark brown, as opposed to the opaque ivory color of casein. The gluten plastic also held a lot of air bubbles. I don't know if these are removable without the use of a vacuum jar or similar vacuum device. This plastic is naturally water resistant, but like the vinegar processed casein, it will still become soft with more than brief exposure to water. It is also easily workable with a Dremel, or similar rotary tool.
My next experiment with plastic is a fairly common bioplastic (the above are also technically bioplastics, though you would probably not find them on a list). It is made from starch, vinegar, and glycerin. The vinegar breaks down the part of the starch that is not a good polymer, so that it can become a good polymer. The glycerine makes if flexible. The amount of glycerine determines the flexibility, so a harder plastic can be made with less, or a more flexible with more. See: http://www.instructables.com/id/Make-Potato-Plastic!/ Note that this is a good application for the starch removed from the wheat gluten.
Starch is easy to obtain, as is vinegar. Glycerin is a bit harder to find. So I have gone to efforts to determine how to make it. In short, you make lye from wood ashes. With lye, fat/oil, and salt, you make soap. The byproduct is glycerin (which is sometimes mixed into the soap, but not for this application). An interesting note is that if you add the right amount of methanol to the lye, you will get biodiesel instead of soap, still with a by product of glycerin. So, instructions for making biodiesel will be in my book as well.
Lord Rybec
Monday, February 28, 2011
Composites
Composites are materials that are made from two components, one of which is a matrix and the other a binder (often called the resin). The matrix is some sort of fiber, while the binder is typically some sort of epoxy resin. Fiberglass composite is made with fiberglass for the matrix and fiberglass resin as the binder.
The benefit of composites is that the combination of matrix and resin can create substances that have most of the good physical properties of both substances, and few or none of the poor physical properties. It is also common for composites to have additional good properties that neither of the original materials had. For instance, fiberglass resin by itself tends to be weak and brittle and fiberglass is extremely flexible and easily pulled apart. Together though, they create a strong, rigid, slightly flexible substance that is also fairly hard.
When making composites, you generally entirely soak the matrix in resin, then remove as much resin as possible. This minimizes the negative properties of the resin, while still effectively binding the matrix (the ratio of matrix to resin is sometimes used as a measure of quality of a composite). In industry this is often done using vacuum bags. (The composite is put into a large plastic bag, then the air and excess resin is vacuumed out.) In a post apocalyptic setting it will probably not be feasible to use a vacuum bag, even if you do happen to have the proper equipment. Instead, a tight fitting mold would work (one with two parts that compresses the material between the parts).
As an experiment, I am going to try using casein glue (see the previous post) with cotton or some other fiber that is commonly used in fabrics (I have to see what my wife has that she does not need). Since casein seems to bind well with cellulose (it was originally used as wood glue), cotton or some other natural fiber would probably be ideal. I think I actually have some scrap cotton around, so I'll use that for the first test.
Another common type of composite is wood laminates. (Look at the edge of a piece of plywood. Notice that it is made from several layers of wood glued together? This is a wood laminate. Plywood has several layers that alternate the grain direction, to make the sheet strong in all directions, instead of just directions that do not follow the grain.) In theory, casein would be a suitable glue for this as well, though probably not as good as the thermal epoxies commonly used now.
The benefit of composites is that the combination of matrix and resin can create substances that have most of the good physical properties of both substances, and few or none of the poor physical properties. It is also common for composites to have additional good properties that neither of the original materials had. For instance, fiberglass resin by itself tends to be weak and brittle and fiberglass is extremely flexible and easily pulled apart. Together though, they create a strong, rigid, slightly flexible substance that is also fairly hard.
When making composites, you generally entirely soak the matrix in resin, then remove as much resin as possible. This minimizes the negative properties of the resin, while still effectively binding the matrix (the ratio of matrix to resin is sometimes used as a measure of quality of a composite). In industry this is often done using vacuum bags. (The composite is put into a large plastic bag, then the air and excess resin is vacuumed out.) In a post apocalyptic setting it will probably not be feasible to use a vacuum bag, even if you do happen to have the proper equipment. Instead, a tight fitting mold would work (one with two parts that compresses the material between the parts).
As an experiment, I am going to try using casein glue (see the previous post) with cotton or some other fiber that is commonly used in fabrics (I have to see what my wife has that she does not need). Since casein seems to bind well with cellulose (it was originally used as wood glue), cotton or some other natural fiber would probably be ideal. I think I actually have some scrap cotton around, so I'll use that for the first test.
Another common type of composite is wood laminates. (Look at the edge of a piece of plywood. Notice that it is made from several layers of wood glued together? This is a wood laminate. Plywood has several layers that alternate the grain direction, to make the sheet strong in all directions, instead of just directions that do not follow the grain.) In theory, casein would be a suitable glue for this as well, though probably not as good as the thermal epoxies commonly used now.
Plastics, glues, and paints
In a few more weeks, I will have a chance to test the forge. In the mean time, let's discuss plastics.
In a post apocalyptic world, it is likely that you will eventually discover something you need that would not be suitable made from metal, or something that would be extremely difficult to make from metal. Plastics are ideal for a lot of products and are generally easier to mold or cast. The problem here is that most modern plastics are made from crude oil products, which will not only be extremely difficult to obtain in a post apocalyptic world, but which also require chemicals which are dangerous and will be equally difficult to obtain. Thankfully, you will likely have at least limited access to ingredients to make plastics that were used as far back as ancient Egypt.
Milk contains a protein (or actually a class of proteins) called casein. This protein can be extracted by making the milk acidic. Generally the easiest way to do this is to add vinegar. My research has yielded many different formulas for this. The one I tested was 2 teaspoons of vinegar for every cup of milk. This was the lowest vinegar to milk ratio. The recipe with the highest ratio recommended 12 teaspoons per cup of milk. The 2 teaspoons to 1 cup of milk worked relatively well for me and in a post apocalyptic setting, I would go with the smallest amount that works well, to conserve resources.
The recipe I used said to warm the milk to simmering, then add the vinegar (2 teaspoons per cup of milk) and remove it from the heat. I did this on an electric stove, though if electricity was not available, you would be doing this over a fire. The protein separated from the milk very quickly (note that you should stir the milk as it heats and as the vinegar is acting). Once the milk had separated entirely into clear whey and lumpy, white curds, I strained out the liquid. This can be done with whatever is available (I used a plastic coffee filter; a paper one would probably have worked better). The instructions then said to add 1 more teaspoon per cup of milk (original volume, not the new volume) and to let it sit for an hour or two (it said to do this in a jar). The curds were supposed to separate further from the remaining water and the added vinegar, but it did not happen the way it was supposed to. Now I'll get back to this in a moment.
It turns out that casein can also be used to make glue (and paint). The previous instructions are actually the first part of making glue, except that you do not add any vinegar after filtering (I am not even sure that adding the extra vinegar after filtering is useful for making plastic; it could probably be skipped without any problems). Once it is filtered, you add some baking soda to neutralize the vinegar. This allows the casein to dissolve in water once again and the result is a sticky mess. I do not recall the exact amounts, but you can add 1/4 of a teaspoon per cup of milk (original volume again, not the new volume) at a time, mix it well, then give it 5 minutes for the reaction to finish. If it is not a sticky, gluey consistency after 5 minutes, do it again. Once you have the right consistency, you can add water to dilute it if needed (there should not be any curds or lumps). This can also be used as paint, by adding more water until you have the consistency you want for paint (food coloring or other pigments can be added for color). Casein glue was originally used as a wood glue, so this stuff has some construction applications (though I would not trust it to hold a lot of weight, without extensive testing).
Ok, back to the plastic. Even after a lot of kneading (as recommended in the instructions), I was unable to get the curds to stick together well enough for molding or casting (it is possible I gave up too soon). So, knowing about the glue recipe, I decided to try something else. I added around 1/8 of a teaspoon of baking soda to the mixture. This allowed some of the casein to dissolve, but not all of it. At first, the result was a sticky, rubbery, fluffy substance. The reaction between the vinegar and the baking soda produced a lot of CO2 bubbles, which made the casein mixture fluffy and airy. Of course, this is not good for a plastic as it will dramatically weaken it. So, I waited for the reaction to finish. This took around 5 minutes. After that, I kneaded the bubbles out of the mixture. It was no longer sticky, but it was still quite rubbery. At this point it was perfect for molding or casting. So, I rolled it into a ball, then flattened it between two pieces of wax paper. It is now between 1/8-1/4 of an inch thick, with a diameter of around 3 inches (this was from 1 cup of milk). It is currently setting. For flat pieces, you should put some weight on it while it cures, to avoid curling or warping. In the morning I will check it and maybe post the results (though, it may not be finished curing).
Some extra notes:
In a post apocalyptic world, it is likely that you will eventually discover something you need that would not be suitable made from metal, or something that would be extremely difficult to make from metal. Plastics are ideal for a lot of products and are generally easier to mold or cast. The problem here is that most modern plastics are made from crude oil products, which will not only be extremely difficult to obtain in a post apocalyptic world, but which also require chemicals which are dangerous and will be equally difficult to obtain. Thankfully, you will likely have at least limited access to ingredients to make plastics that were used as far back as ancient Egypt.
Milk contains a protein (or actually a class of proteins) called casein. This protein can be extracted by making the milk acidic. Generally the easiest way to do this is to add vinegar. My research has yielded many different formulas for this. The one I tested was 2 teaspoons of vinegar for every cup of milk. This was the lowest vinegar to milk ratio. The recipe with the highest ratio recommended 12 teaspoons per cup of milk. The 2 teaspoons to 1 cup of milk worked relatively well for me and in a post apocalyptic setting, I would go with the smallest amount that works well, to conserve resources.
The recipe I used said to warm the milk to simmering, then add the vinegar (2 teaspoons per cup of milk) and remove it from the heat. I did this on an electric stove, though if electricity was not available, you would be doing this over a fire. The protein separated from the milk very quickly (note that you should stir the milk as it heats and as the vinegar is acting). Once the milk had separated entirely into clear whey and lumpy, white curds, I strained out the liquid. This can be done with whatever is available (I used a plastic coffee filter; a paper one would probably have worked better). The instructions then said to add 1 more teaspoon per cup of milk (original volume, not the new volume) and to let it sit for an hour or two (it said to do this in a jar). The curds were supposed to separate further from the remaining water and the added vinegar, but it did not happen the way it was supposed to. Now I'll get back to this in a moment.
It turns out that casein can also be used to make glue (and paint). The previous instructions are actually the first part of making glue, except that you do not add any vinegar after filtering (I am not even sure that adding the extra vinegar after filtering is useful for making plastic; it could probably be skipped without any problems). Once it is filtered, you add some baking soda to neutralize the vinegar. This allows the casein to dissolve in water once again and the result is a sticky mess. I do not recall the exact amounts, but you can add 1/4 of a teaspoon per cup of milk (original volume again, not the new volume) at a time, mix it well, then give it 5 minutes for the reaction to finish. If it is not a sticky, gluey consistency after 5 minutes, do it again. Once you have the right consistency, you can add water to dilute it if needed (there should not be any curds or lumps). This can also be used as paint, by adding more water until you have the consistency you want for paint (food coloring or other pigments can be added for color). Casein glue was originally used as a wood glue, so this stuff has some construction applications (though I would not trust it to hold a lot of weight, without extensive testing).
Ok, back to the plastic. Even after a lot of kneading (as recommended in the instructions), I was unable to get the curds to stick together well enough for molding or casting (it is possible I gave up too soon). So, knowing about the glue recipe, I decided to try something else. I added around 1/8 of a teaspoon of baking soda to the mixture. This allowed some of the casein to dissolve, but not all of it. At first, the result was a sticky, rubbery, fluffy substance. The reaction between the vinegar and the baking soda produced a lot of CO2 bubbles, which made the casein mixture fluffy and airy. Of course, this is not good for a plastic as it will dramatically weaken it. So, I waited for the reaction to finish. This took around 5 minutes. After that, I kneaded the bubbles out of the mixture. It was no longer sticky, but it was still quite rubbery. At this point it was perfect for molding or casting. So, I rolled it into a ball, then flattened it between two pieces of wax paper. It is now between 1/8-1/4 of an inch thick, with a diameter of around 3 inches (this was from 1 cup of milk). It is currently setting. For flat pieces, you should put some weight on it while it cures, to avoid curling or warping. In the morning I will check it and maybe post the results (though, it may not be finished curing).
Some extra notes:
- This plastic is not very strong without a little bit of extra processing. Thick pieces should be fine, but thin pieces like the one I am making will probably be easy to bend until they break. If you happen to have access to formaldehyde, soaking the plastic in a 5% solution will strengthen it. This can take a long time however. One source said that plastic 25mm thick can take over a year of soaking to be entirely strengthened. Also, this process tends to cause warping. I can think of a few other ways of strengthening this plastic.
- Adding some kind of fiber should improve the strength. Cotton would probably work, fiberglass might work as well. If you want to make actual composites, you should probably use a thick mixture of the casein glue on cloth made from the chosen fiber. More on this in the next post. Also, this is supposed to be water proof once it is totally dried and is porous enough to paint.
- Casein is a food protein and as such will eventually spoil if left wet. Refrigerating it will extend its usable life. These products should last around a week or so refrigerated. Generally, it is probably best to only make them as they are needed.
- Even after it is dried, casein plastics will decompose if left wet for long periods of time. This is not generally enough to be a problem in daily use and is actually a good thing. Unlike petroleum plastics, Casein plastics are biodegradable.
- As this plastic can warp when drying, it has been common to cast a piece in a large chunk, then grind it to the desired dimensions. Historically, casein plastics used to make buttons were cast into long rods, cured using the above formaldehyde solution, then sliced and drilled to make the buttons (with additional grinding for more complex patterns). I will probably end up grinding the piece I am making into something, though I have not decided what yet. In theory, you could use a CNC milling machine to mill this plastic into useful objects (though, this would not be that useful in a post-apocalyptic world).
Monday, January 31, 2011
Forge: 12 Quart Pot
My 12 quart pot forge is nearly finished. It has been lined with 3cm thick of the refractory cement discussed in the last post (5cm on the bottom). Since one of the ingredients is concrete, I am having to give it time to cure, so I have not tested it yet. Once curing is finished and the lining appears dry, I will be cooking it, starting at 200F and working slowly up to 450F. When that is finished, I will line the forge with a thin layer of fireplace cement (to protect the refractory cement lining). I'll have to go through the cooking process again to purge the water introduced in the fireplace cement, then it should be ready for firing.
Again, I am using a blow dryer for air. It is possible that I might need to use more than one, given that the volume of this forge is around 10 times the volume of the flower pot forge. (I am using bigger pipe this time, though, so the ability of the blow dryer to provide airflow will be increased.)
In addition to the forge, I used the leftover refractory to make a lid. There was only enough for a 1.5cm thick lid, which may not be sufficient, but I can always add more cement to one side (the only ingredient I do not have a lot of left is sand and that is pretty easy to come by). Also, I will have to cut a hole in the middle of the lid to allow air flow. Since the lid is pretty thin, this may be difficult without cracking it. The benefit of the lid is that I can use it to contain heat when melting metals.
Once the forge is fired, and the refractory mixture tested, I'll post complete instructions on how to make the refractory (assuming it works properly).
Again, I am using a blow dryer for air. It is possible that I might need to use more than one, given that the volume of this forge is around 10 times the volume of the flower pot forge. (I am using bigger pipe this time, though, so the ability of the blow dryer to provide airflow will be increased.)
In addition to the forge, I used the leftover refractory to make a lid. There was only enough for a 1.5cm thick lid, which may not be sufficient, but I can always add more cement to one side (the only ingredient I do not have a lot of left is sand and that is pretty easy to come by). Also, I will have to cut a hole in the middle of the lid to allow air flow. Since the lid is pretty thin, this may be difficult without cracking it. The benefit of the lid is that I can use it to contain heat when melting metals.
Once the forge is fired, and the refractory mixture tested, I'll post complete instructions on how to make the refractory (assuming it works properly).
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