Wood ash needs to be washed many times to take the soluble material and the fluxus off, and then the material is screened and then dried. The rice husk ash is processed the same way; I wash it and then I pulverise it in a ball mill, to get it to pass through a 100 mesh screen. My brother heats his shop with wood, so there`s an abundance of ash around and I like using ash that way, as it`s something that people throw out. I also get my rice husk ash from powerplants that use rice husk for fuel; the ash is a byproduct. However you can`t buy directly from these people, they don`t want to be bothered by potters. You have to buy mountains of it; they want you to buy a truck load which is about 42000 pounds, so I had to purchase enough for a lifetime.
I like learning about how to bring out the best in that material. Now, I`m not a wine maker but I imagine it`s a lot like that process, where they are trying to extract the highest quality product from the soil and the grape and that`s exactly what I want to do with my glaze materials. For years now I have been asking what is the best way to process rice husk ash? How fine do I have to grind it or leave it coarse, what do I have to blend it with and what kind of mesh do I use there? What kind of wood ash is best? I was fortunate enough to work with a fellow potter, Paul Wakenight, who happens to be a scientist. He was a huge help in setting up experiments and investigations from which I learnt a great deal, and the experience was invaluable.
Here are some pictures of burning apple wood for ash: