|A technical explanation||
I welcome comments and criticism from anyone who knows more than I do.
|My way of
working is very different from most other lifecasters' methods, so I am
including this explanation.
If you are not experienced with plaster, you have no business approaching any living model with wet plaster. Plaster gets very hot, and a sharp plaster edge could slash you open.
Beginners should stick with plaster gauze and alginate, and practice my plaster technique on a big balloon not inflated too tight. No joke. And read the whole thing, fool.
What I am doing when I make a lifecast
mold looks quite simple, but isn't easy in practice. I am very experienced
working with plaster in my regular business, architectural casting.
diaphragm is the large area on everyone's torso below the ribs and above
the pelvis, a diamond shaped area of muscle. The model's diaphragm moves
in and out, stretching the thin wet plaster on inhaling and vice versa.
The plaster mat layup moves with the diaphragm until the plaster takes
a set, and at that moment, the whole body had better be laminated, because
the tiny movements of any living model will crack the thin layer like
My worst mistakes have been painful for the models, or just wasted our time. Not everyone can model; some people can't stand it, or just can't keep still at the crucial moment. Assistants, often models' boyfriends or husbands, have done things I didn't catch. We nearly tore a girl's ear off when the clay behind her ear (trick!) fell away, and we cast her without it; and I did capture my first model's pubic hair: I told her to grease up well down there, but I was too shy to check.
I was able to break the plaster prong
which formed where it slid down between her thighs. Now I grease what
needs greasing, and use plaster gauze over all thick hair in the field
of action. Body areas which are not to be included in the piece should
be shrouded with plastic or cloth to keep them clean.
Here's the big plaster secret: Plaster takes a set, and then it starts heating up. First, the set. It could be easily scraped around, but it isn't a liquid anymore. Then, the heat. People ask, How hot does it get? That's a trick question. Each cubic centimeter of plaster puts out just so much heat [calories]. So the thicker you work, the more heat you (the model, really) must deal with.
So the big idea in my technique is this: That first layer has hardened, and is starting to heat-up. And there you are, covering it with new, cool plaster. The heat goes into that second layer, warming it and causing it to harden sooner, and cooling off that first layer by so doing. As plaster has its exothermic reaction, it grows vastly stronger. It's crystallizing, actually.
The thickness of the mold is still remarkably thin, maybe a quarter of an inch. Where it goes into a body crevice it will be thicker. I take the mold off the model as soon as the second or third layer hardens (maybe we missed some areas with the second layer). More tricks are involved. That warning about the plaster slashing your model makes sense when you look into a mold -- plaster which hardens in a body crevice is that sharp. The model is usually fascinated to see the mold, and glad the hair-yanking is over. She keeps most of her hair but a few do pull out. Her skin may be bright pink but will quickly return to normal. There will often be small bruises on the nose where eyeglass pads normally press in, for some reason.
If you need to make a complete full-round bodycast, you'll need to have made nice smooth strong edges. You'll go around to the back of the model, paint the plaster edges with oil soap solution, and start again. I don't care to do this very often.
I think that as the artist, my work is in choosing the pose and presenting the viewer with one bas-relief vision. But if it were easier to make a full-body casting, perhaps my vision would be different! Fred Reenders has this down, with a completely different technique. He likes smooth, marble-like surfaces, while I prefer real skin texture. I guess you come to prefer what you're good at doing.
The mold invariably needs some work. Air bubbles, big and small, are in the mold surface. They need to be filled carefully. Often there are a few cracks and ruptures to mend and sand. The edge needs defining; this is crucial to the look of my pieces. Remember reinforcing the edge? If you missed some spots, now you catch them.
When the mold has fully dried, it can be cast. To cast concrete, it needs to be coated with form oil. For plaster, use oil soap solution. For polyester fiberglass (FRP), shellac and wax it. To cast wax, for bronze, generally you cast in plaster, make a thin rubber mold of the finished piece, and pour wax in that mold. For clay, just work in the clean mold; see my ceramics page.
| I won't
go into detail on casting here, but I cast Hydrocal plaster in my casting-plaster
mold. The H'cal is so much harder than the regular that I can pretty well
bust the mold to pieces without harming the casting.
Regarding aesthetics, I insist on displaying the piece in the same plane that it was created. Nothing looks creepier to me than the popular facemasks where the model was lying on his back, and the cast is displayed hung on the wall. The effects of gravity are clear. Viewing it as it was cast looks much more natural. This rule may be broken but should be understood. Again, by working thin, the plaster's weight does not depress the flesh so much.
|This should give my fellow-artists a good idea of what I'm doing, and everyone else an idea of what goes into this art.|
back to moldmaking page
main index page