In January 2020, I started a new chapter in my life as a person and as an artist by moving from Tokyo to Seattle, and when I was preparing to restart my ceramic activities, there was something that really surprised me.

That is, the fundamentals of ceramics, from clay to glaze materials, are completely different between Japan and the United States. I knew that I couldn't get the clay I used to use, but I had no idea that I would have to learn the glaze recipe from the beginning.

This is the moment when I realized that ceramics is an art form that depends on the environment, where different earths have different ingredients.

For example, in Japan, the basic recipe for glaze is very clear.It is a 7:3 mixture of feldspar and ash. Then, various ingredients are added to this mixture to change the texture and melting point.

However, when I went to a pottery shop in Washington State, they didn't have any "ash" as far as I could see. There was volcanic ash, but I guess it is different from the lime or wood ash sold at pottery shops in Japan. (I bought some volcanic ash, but haven't used it yet. I'll try it later to see what effect it has.)

In the U.S., the feldspar is not so different from the Japan has, but they use a material called "whiting" or frit as an alkali substitute for ash. Geeky as it may sound, whiting is a material that is almost 100% CaO, and frit is a glass powder that makes the feldspar component of the glaze base more soluble. Then add some stone powders such as kaolin, silica, talc, etc. to it to make glaze stable.

As a metaphor, if Japanese glaze materials, which are mined from nature and used almost unrefined, are "Herbal Medicine”, American glaze materials are " Western Medicine," which is made by refining natural materials, separating them into pure materials, and mixing them chemically. 

I was very disturbed by this situation. If I couldn't use the recipes I had been using, I would have to start my studies all over again.

So I desperately tried to learn the "Zegel formula," a difficult formula invented by a German scientist in the 19th century to develop mixing rates for glaze textures. I was not a good student of mathematics, and in the middle of my study, my brain said to me, "You've reached the limit of your understanding! This is the ceiling of your ability!" Poor my blain...

But thanks to the wonderful information network of the Internet and the great civilization of Microsoft Excel, that allowed me to create Zegel equation by simply entering the type and quantity of materials. This is a point I would like to brag a bit about to my professors in my country.

The Zegel formula is not a panacea, but luckily I was able to get a book with American glaze recipes, so now I can mix my glazes again with available materials here. As for coloring materials such as oxidized metals, it is the same as in Japan.

Also, one more another thing that surprised me was the variety of commercially available glazes sold at pottery stores in the U.S.  In Japan, people would say like, "It's hard to make a red color glaze!”.  However, glazes of various colors and textures are available at the U.S pottery store without begging professional to teach you the secret recipe. The variety and quality of U.S. glazes are great that I don't feel the need to mix my own glazes for small quantities.

Japan, with its emphasis on tradition, and the United States, where technology and information are shared widely through the market. I think its difference is thought-provoking.

Also, the firing system is also different between Japan and the U.S. Fortunately, I had been using an American-made electric kiln in Japan, so I didn't have much trouble. And I'm getting used to Fahrenheit.

Someday, when I move to a bigger house, I may build a wood-fired kiln and make my own natural ashes to try making "botanical ceramics". I'm sure it will be fun to research various other styles.

Well, that's it for today. See you next time!






これがワシントン州の陶芸屋さんに行くと、私が見た限りでは「灰」というものを扱っていなかったのです。火山灰(Volcanic Ash)というものはありましたが、日本の陶芸屋さんで売っている石灰や草木灰とは異なるものでしょう。(買ってみましたがまだ使っていません。どんな効果があるのか、後日試してみます。)











Saori Matsushita