Lately I’ve been working on ways to bring out the crackle in my teabowls, as well as make the crackle finer (without having to use them for decades or centuries, or reformulate my glazes, so in other words: cheat).
These two bowls had big crackle ( 1cm +-) and I reheated them, then doused in cold water.
***WARNING: Ceramics generally don’t like to be heated or cooled quickly. Don’t do this if you’re going to be upset about breaking a bowl!***
For the kohiki bowl, I heated and doused once to make the crackle smaller, then reheated to open the crackle wider, and closed the damper on my stove, to get that carbon to penetrate the crackle.
Because the body and the glaze were vitrified, but the white slip in between wasn’t, spots (where the slip was thickest) on the rim separated from the body and had to be restored with lacquer and gold (*1)
The results vary, and it is high risk, but you can get an idea about how your bowl may mature over years of use, and plus it’s just fun to play around with fire…
Another common way to bring out the crackle in you ware is to boil it in a pot of strong tea for a few minutes. The tannins will then turn brown, especially if you put the piece out in the sun to dry (or any other UV light). For an even darker, quicker reaction, after the piece is dry, apply some iron acetate. The iron acetate reacts with the tannins and turns quite black over a period of 24 to 48 hours. This is actually an old woodworking technique that I applied to pottery, and it works well, in addition to being non toxic.
***Results may vary***
(*1: I didn’t use real gold for this bowl, but I would on a very nice piece. For this piece I used a brass based metal powder. For more info on this kind of repair, check out Dave Pike’s blog, or store on Etsy)