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
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