Plaster casting
I have just spent 2 days in the plaster room. Most ceramic artists I have met here do not pledge much allegiance to plaster as a material, in fact many of them downright loath the stuff. For me, it’s a very necessary evil. I always work with plaster. I couldn’t get along without it. (Nearly) everything I make comes out of a mould.
I tend to make all my prototypes, save them up and have a massive plaster casting session, which is perhaps why it seems so arduous. And it is very messy. And sometimes it doesn’t work – the plaster might have gone off, which is really bad news and could destroy many hours of work, or it sets too quickly; basically it’s a race against time.
But the plaster room at Guldagergaard rates among one of the best plaster rooms I have ever worked in. It is a veritable palace when it comes to plaster workrooms. And Matt, one of the current assistants, has been polishing it with a toothbrush as far as I can see. Which raises the stakes even higher because there is the fear of messing up an exemplary room up juxtaposed with the speed with which the stuff has to be slopped around. Phew. Glad it’s over.
Anyway I have cast ten prototypes. Two are open press moulds, for which I am using my new method of pouring liquid clay (slip) into the moulds as the results are so much smoother, especially with porcelain. The other eight are closed moulds, which means I will pour slip into them, wait for it to solidify to the right thickness against the plaster walls, and then pour the excess out. This is a method I have only ever tried and have never employed in my work. So I am interested to see what the results are.
The process to make the moulds is to cast the first part, i.e. covering the clay prototype. Then this is turned over, exposing the clay form inside, seal the surface of the freshly cast plaster with a resistant soap wash to prevent the two parts from sticking and then casting the ‘back’, taking car to add a piece of clay that will form a pouring hole for the slip.
