Some of you may have read my earlier post about how I create my small holiday ornaments...as well as the larger ceramic items.
I have added a new line; wall plaques engraved with various "cute" sayings. For these, I use an entirely different approach.
The plaques are molded, in a sense, but instead of liquid clay slip being poured into molds, I begin with moist clay in a block, much as a potter might use to throw on a wheel. I have several molds, this type more properly known as "jigs," into which I fit pounded slabs of clay.
Pounded? That's right. Once the clay is cut from the large block, it is unlikely to be 100% the correct size and shape, or thickness. Chances are, a few pieces will have to be squished together to form the whole. The pounding makes sure all the layers have become one, and there are no air pockets in the middle. Air pockets spell death to ceramics. The least little bit of air in the middle will have whatever tiny amount of atmospheric moisture in it, that was trapped when the clay was molded. In the kiln, this becomes steam, and expands. It has nowhere to go, so "kaboom" goes your piece!
The pounded clay is then laid into the jig, and pounded further to fill in to the corners. Then, it is rolled with a roller to smooth the top. (The jig is fastened to a smooth surface, so the bottom is more or less smooth already.) Once the jig is completely filled, any excess is cut from around the edges, and the clay allowed to sit and start to dry. There is a lot of moisture; it can be left to sit even overnight in cool weather.
After it has hardened up enough to handle without warping too much (clay has 'memory' and a warped piece will come out warped, even if it was re-flattened before finishing the drying process). At this stage, using a sharp pencil, I scribe in the sayings, and blow out the clay shreds that result. I then add whatever edging treatment I desire, and set them to fully dry. Depending on the weather (read: time of year), this can be overnight to almost a week. These plaques are solid clay, ¼" thick.
Once it is fully dry, it then proceeds into the cleaning queue, to be pepared for firing, from that point, the same as any other green ware piece.
After firing, I use a different type of finish treatment to get my 'rustic wood' look. These paints are oil-based, and each coat takes almost a full week to dry fully, even in warm weather. Then, the sealer coat is applied, and they are ready for sale.