More Wine Cups
April 30, 2008 by Melynn
A couple more yin and yang wine cups (as my blogging friend Katy calls them), although these aren’t exactly usable in this state – the result of a somewhat failed “naked raku” experiment my ceramics class decided to take on. We got this far by painting terra sigillata on leather hard porcelain and burnishing the surface with a soft towel. Then we fired the pieces to Cone 010. After that, we dipped them in 2 different raku glazes that my teacher found on the internet and fired them in the Raku kiln. The idea is that once the pieces are taken out of the raku kiln and placed in a combustible material (newspaper and sawdust in this case) contained in a reduction chamber with a lid, the smoke from the burning material leaves a free-form pattern on the surface where the glaze has cracked like eggshells. The glaze is supposed to be easy to scrape off after the piece has cooled enough to plunge into a tub of cold water, but for some reason we had a hard time with it, most likely because we left out the “plunging into cold water” part. The cup on the left came out a little better once I sanded off all of the black ash and polished the surface with wax, but the coating on the white one was like chipping glass. After cutting my fingers on the shards a few times and breaking the rim, I gave up, but at least I got a photo of it while it was still in one piece. There’s definitely more research needed to be done on naked raku if we were to try it again. Besides that, now I know that raku isn’t meant for functional ware – it isn’t food safe or water resistant, but used for decoration only. The cup that made it through does make a nice pencil holder though…
Was there a reason why you omitted plunging them into cold water? I would assume that the shock of going from one temperature to another, radically different, would be the key here.
Hi Frank, yes, it is the shock from one temperature to another that helps loosen the outer coating. We figured it out about half way through (we were basically reading instructions as we went), but once we did, the water we used wasn’t cold enough. Here’s a link to a student in another class in the same studio that spent the term learning about naked raku. It was this class that inspired us to give it a try, but we obviously didn’t do our homework to the extent they did, and their results were spectacular in comparison.