I’ve been putting off posting these photos because it pisses me off sooo much. We had bisque fired all the tile for this job before our out of control road trip. When we got back we started glaze firing the subway tiles first. They look awesome, the finish is super glossy and they have a nice amount of crackle. We had fired two loads of the subways 80-100 fit in our kiln, and glazed and fired another load of them along with the border tiles and the vineyard grape motif large tile. It’s all low-fire earthenware stuff so we only go to cone 06 (1841°). We started to unload the kiln after it had cooled and the big one was 3 shelves down.
While we were in Indiana we went to Brickyard Ceramics and spoke to a scientist from American Art Clay Co. about this very problem of large slab tiles breaking. We thought we had it figured out, but we had never made a piece like this that has such a variation in thickness. We called him yesterday and he was quite helpful. He told us that by looking at these photos that the tile suffered a thermal shock while heating up during the glaze firing. We had ramped up the heat too quickly not letting the entire tile heat evenly enough and that most likely caused the cracking.
We spent most of the afternoon Wednesday building another one and will build two more tomorrow. I must say the one we just made is even cooler that the one in the photos. We made some templates for the leaves that makes it go faster,and we used one of the 6″ rollers we just got for the slab roller I get to build as a rolling pin to roll out the background slab. Once we get the tile we made today cleaned up I’ll post a photo. As hot as it is down here hopefully it wont take more than a week or so to dry out enough to bisque fire.
I was pretty happy with all the measurements, everything fits together well. I seemed to have calculated the shrinkage right and we precut the miters on the border pieces before we glazed them so they wouldn’t have any rough edges.
scott in jupiter