This glaze is made of clay that our friend brought from the volcanic island of Madeira. The surface is brownish with spotts and when applied in thin layer it comes out darker, it’s matt and it doesn’t flow at firing temperature of 1250 ºC.
With this glaze it’s all about shrinkage trick. Glaze is mostly made out of porcelain and ball clay, so it needs longer soaking time. It’s fired between cone 8 and 9, depends of procentage of the ingredients. During the firing process its shrinkage is bigger than the shrinkage of clay itself. It makes beautiful surface of melted cracks and little craters. Its downside is that it can deform thin objects.
Neverless this glaze is perfect for combining with other colour glossy glazes. It just makes amazing unpredictable effects.
In november 2015 David went to Janja Gora, Croatia to fire some ceramics he made in a special woodfire kiln similar to the japanese anagama. The kiln is named Janjagama. It was David’s long time wish to fire ceramics in a high tempearture wood kiln. Someday he would like to build his own kiln, he already has plans made!
It was a great experience as the people he met there were very nice and hospitable.
Firing ceramics in this way is very hard work, it takes about two days of loading the kiln with woods to reach temperatures over 1300 °C. And you have to know how much and when to load the kiln. David says you have to listen to the kiln and the winds also and it will tell you when to load woods.
When the final temperature is reached (1311 °C), the kiln has to cool and it takes about one week.
Some pieces didn’t come out as imagined because David made the glazes too strong, so they didn’t melt as expected. But it doesn’t matter, he knows now how to make them just perfect. Some of the pieces that he didn’t like he burned again in our electric kiln.
Some woodfired pieces came out just amazing, we can see “the way of fire”, ashes melted and on some pieces the effects are the result of ashes mixed with glazes that David made.
There are some fotos of the firing process, loading the big Janjagama: