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).

Forge: Final Refractory Research

Ok, so the experiment with the clay and perlite is finally finished. Perlite already contains a lot of alumina, so I tried just mixing clay with powdered perlite (I used the bottom of a metal cup to crush it; a better option would have been a ball mill). The first brick was even parts (by volume). It cracked into two pieces and had a lot of spalling. The second was 2 parts perlite to 1 of clay. It broke in two, with only a little spalling. The last was 3 parts perlite powder to 1 part clay. The surface melted slightly, but there was no cracking or spalling. (I believe the last brick was tested after I started using fuel pellets, so the temperature was probably considerably higher than with the first two.)

So, my plan was to line the next forge with the 3 to 1 mixture of perlite powder and clay. I was also going to add some non-powdered perlite, but only pieces between 1mm and 3mm. I ran into a problem with this. Powdering perlite takes a long time. Also, perlite is mostly air, which means that an 8 quart bag of perlite yields only about 2-3 cups of powder. So, I started looking around for alternative refractory mixtures again.

This time I found a mixture that looks really good. The recipe is 2 parts clay, 2 parts silica sand (beach sand is primarily silica; play sand at hardware stores is also mostly silica), 1.5 parts perlite, and 1.5 parts Portland cement. I used this mixture, but I added the 3-4 cups of powdered perlite to the mix, and I also increased the portion of regular perlite, to improve its insulating properties.

I have not tested this mixture with heat yet, but I have finished the forge and will be testing it once it is totally cured and dried.

Forge: New Design

Ok, scratch the paint can. A while back I bought a 12 quart stainless steel pot. Originally I intended on using it for making charcoal, but then I realized that it would make a much better forge than the gallon paint can. It is also much larger, giving me more work space.

For air input I cut a hole in the side just large enough to accommodate steel plumbing pipe.

More on this later today.