Forge: Fireclay

Ok, so I have recently discovered that there is a terminology issue with my research. It goes like this: Many of the websites I have been finding have referred to refractory clay as "fire clay", but, as it turns out, the term is more often used to refer to clays that are fired to make pottery, etc. The site that I obtained my silica/alumina ratios was one that used the term to refer to pottery clays in general. So, normal pottery clays usually have between 24%-34% alumina and 50%-60% silica. The clay I bought was manufactured by Seattle Pottery Supply, so I emailed them and found that their Klamath Buff clay contains about 50% silica and 30% alumina.

To overcome this terminology issue, I began researching the contents of firebrick, since the term "firebrick" is used almost exclusively to mean refractory brick (although, in some cases it is called "insulating firebrick", while low temperature firebrick is just called "firebrick"). Refractory firebrick generally contains from 37% up to 90% alumina, with successively lower amounts of silica. The higher the alumina content, the higher the heat it can handle, but the softer it becomes. So, my current priority is to use electrolysis on aluminum cans to make alumina. I am planning on using 50%-70% alumina (this will be fun math, since the clay already contains 30% alumina).

A few days ago (around the time of my first Forge post), I took a 12v transformer I had laying around and a 5 gallon paint bucket. I attached the negative lead to a piece of stainless steel that I had used for this sort of thing in the past. The positive lead was attached to an aluminum can. Both were submersed in water (the copper leads were suspended a short distance above the water, to avoid contamination; copper will corrode in these conditions, if it is in contact with the water) and I turned the transformer on. For an electrolyte, I used baking soda (at 12v salt breaks down into chlorine gas and sodium; the sodium reacts with the water, contaminating it). The baking soda may be making the water more conductive than I want, so I will be looking into this when I have more time. Also, there is some evidence that the baking soda may be breaking down, so I will eventually have to do some more research on this.

Anyhow, after the first can had been mostly oxidized, I attached a Boyardee Ravioli can to the positive lead, assuming it to be made of aluminum. The water quickly turned a reddish brown. Evidently many modern "aluminum cans" are actually made of steel. I suspect large juice cans are also steel. So, next time I need iron oxide I know which cans to use (once the forge is finished I will be needing some of this for making thermite, which will yield iron and alumina when burned; I will probably write an article on this subject once I get there).

I will post again as things develop.