Now that the plaster mold is mostly dry after two days in front of two box fans on “high” I decided to try pressing the first clay in it.
It took about a half hour to carefully press the clay in, and it took about 35# of clay.
I added the interior webbing that all of the architectural terracotta originals my work is based on- have for structural stength and integrity. My pieces don’t need the strength so much since they are not load bearing elements meant to support three stories of brickwork above them, so the webbing and wall thickness is between 5/8″ and 1″ thick, while the antique originals were typically specified to be 1-1/4″ to 1-1/2″ thick.
Here’s a view of the back, I think in about a couple of hours it should be firm enough from the plaster mold absorbing moisture from the clay that it will be firm enough to at least remove the sides of the mold. To remove the clay pressing it will have to stiffen further enough to support it’s own weight.
I’m pleased to see that the first pressed clay came out better than expected, only a little minor defects need touching up, here’s a photo of it fresh out of the plaster mold, because it’s late I’ve wrapped it in plastic to mess with tomorrow night.
About 3 hours later… I wound up simply standing the mold on edge, taking the band off, carefully removing the two sides and top and then removing the large base section leaving the clay model resting on it’s bottom side on the bottom plaster section. Then I placed a plywood sheet with 3 strips of plywood against the clay models’ back and just tilted the whole thing horizontally to leave the clay model supported on the 3 strips on the plywood. The strips act as spacers to allow air to circulate inside as it dries.
I’m guessing a half hour or so of “cleanup” and re-detailing touchup will be what it takes, the small defects are mostly where one bit of pressed clay merged against another leaving a very tiny “line” or wrinkle. Some of that might be controllable by technique, or it might just be the nature of the beast with pressing clay- as you work some of the clay starts to dry and the edge of that leaves a little line when more damp clay is pressed next to it, something like that seems likely.
The main defects can be seen on the upper left part of the smooth “V” and on the bottom edge where the face met the side, that 90 degree edge has some “lines” or wrinkles where the very surface of the clay didn’t quite merge 100%
It took about a half hour to press the clay, it could take a couple of weeks to dry out slowly.