|Monthly Tech-Tip |
The firing temperature: Both are fired at cone 04. Left: Zero4 porcelain, this fritware is totally dense and durable yet fired ten cones lower than typical. You can make it. As an appreciator of the process more than the product, just drinking out of this amazes me! Right: Milk glazed earthenware. The inside glaze, G1916Q, was fired onto L215 at cone 04. The 250F preheated mug was quickly dipped in milk after which it steam-dried. I then refired it at 610F to get this effect. To improve durability I dipped the outside in silicone sealant. The surface looks and feels like leather, drinking coffee out of this is an amazing experience!
In the youtube video (link below) a Karelian potter uses this technique to make cookware. He immerses pieces, while still hot from the bisque kiln, intp a bucket of milk. After a few seconds he withdraws them and they steam-dry quickly. I did not preheat these Plainsman L210 pieces, they were just bisque fired to 1850F. The Russian potter claims to milk-fire his ware to 300-350 degrees, assuming that is celsius I fired these at 500F/hr to 612F (350C), then held for 10 minutes. The surface is smooth and pleasant-to-touch, it is odor-free. The potter claims it retains this surface over many years despite repeated oven use. This clay body, L210, is well suited since it fires to a smooth unglazed surface. Indigenous cultures throughout history have learned how to prepare, cook and store food in terra cotta clays like this, they withstand thermal shock better than vitrified stonewares and porcelains. And continue to service even if they do crack.
Using milk as a glaze
Don't just try this, go into it as a project with your eyes open to the issues you will meet.