Tuesday, March 10, 2009
Another use for the needles
This the watched pot that won't boil. That's the mold that will tell me if Vixen can be cast in one piece. I've placed it next to the kiln (which has been running pretty steadily for the last few days) hoping that it will dry faster. So far the only thing drying have been the rubber bands!
I almost forgot to mention that I found another use for the large gauge veterinary needles. One of the things I wanted to try with this test mold was pouring the head piece. Horses with turned heads are problematic in ceramic, and usually require a separate piece to fit over one side of the head and neck.
"Finn" has one of these. In the past I've made these by hand, much like I did with the tail piece for "Imp". I thought with "Vixen" I would try to include this piece in the master mold, and pour it just like the others.
The problem with pouring these kinds of pieces is that they wrap under the original. The poll piece sits on top of the ears and forehead, but the second piece has to include the underside of the head.
Since the plaster pours from the top (the area tinted blue), what often happens is that some amount of air - often quite a lot! - will get trapped under the jaw (the area tinted lavender).
What I found was that I could fill the needles with newly mixed plaster, tip the mold sideways like I have in this picture, and then insert the needle just past the tip of her nose. I measured that distance and marked the needle, since the last thing I wanted to do was inject plaster into the rubber! But doing it this way allowed me to fill the area under the jaw. Then I turned the mold back the normal way and continued filling the rest of the cavity. The finished plaster piece was completely bubble-free.
The nice thing was that plaster cures slowly, so the needle can be cleaned and used again. With the rubber the syringes have to be thrown away since it is impossible to clean them afterwards. So I have the marked needle ready to use again for future plasters, if this mold design works.
In the meantime, I've reclaimed my studio and have started glazing again. It feels good to get back to all the projects I left hanging when I started working on the molds. I've enjoyed pushing myself with some more complex molds, but the end results aren't nearly as charming as finished, shiny horses!
at 4:38 PM