This little piggy's called "Cappuccino". My first night attending a Sculptors Queensland forum there was a lot of talk about making moulds, using silicone and repetitive casting. One of the attendees, Graham Marshall asked, almost in passing, what about the tried and tested method of making a plaster mould that you smash off after the casting? So off course I decided I should give it a go. Despite the apparent waste and "one-off" nature of the process, it's really quite an economical way of manufacturing something. The clay and plaster are cheap and the fibreglass is rigid and durable. And since you're only making one, you don't have to worry too much about getting the process right or not breaking anything.
I've used the filtered terracotta for a couple of jobs now and I'm happy with it's smoothness and the absence of granular particles. The initial modeling was quick too, done over a couple of short sessions on consecutive days. And knowing I would sacrifice the mould, I made no real effort to smooth the clay. In fact I was deliberately rough, leaving the surface textured with broad trowel marks.
When applying the plaster mould I was aiming for a thickness I could rely on for stripping out the clay but not so thick as to prevent me breaking it off the finished fibreglass without too much trouble. I sealed the mould with PVA glue, just cause, which proved fortuitous. After stripping the mould, a few pieces of plaster resisted removal, but I found soaking it in water dissolved the PVA which was enough to dislodge most of the stubborn remainders.
At this point I got stuck. I couldn't decide how to make the base. I had lots of ideas, large and elaborate, none of which came to fruition. So the whole thing stalled of several weeks. In the end I figured simplicity was best so I made a backboard from MDF cut with a jigsaw and routed with bullnosed edges. Now that I've got it down, I hope to make more of these "one-off's", except I've already started other different stuff and I have a few ideas for more "Un-tried" pieces. So for now I'm filing this one away.