Molding a Sculpture Tutorial
Mold making is sometimes very difficult, and getting the correct materials is really important. The stronger kind of mold you have, the longer you will be able to use it. Plaster of Paris can be used for molds, but you’ll get only a couple pulls from it. Likewise, Ultracal will give you 10 to 15, and fiberglass can be used hundreds of times.
For this mold making you will need the following!
- Ultracal 30 (or whatever material you pick)
- Three 5 gallon buckets
- A mold release (clear spray paint works)
- Burlap or plaster gauze
No matter what kind of mold you are using, be sure to apply a mold release. When the mold heats up, it creates a suction. If you’re only doing a facial appliance, having a mold that has a bar in the back to pull against is extremely helpful. Since I used ultracal 30 for this mold, I used vaseline for my mold release. Be sure that you check with whatever material you are using so that the release agent you use doesn’t stop the curing of your final product.
My mold was a one piece mold , but I have explained some of the parts of a two part mold as well.
You want to create a “wall” around your mold. I used WED clay because for my sculpture I used oil clay, but there’s a lot of different ways to do this. Cards work too.
Build this wall up around your sculpture pretty close to the seam line if you have a head like this, or if you’re doing a two part mold, make it as seamless as possible. This means really smoothing out the edges. If you don’t do that, you’re going to have a very visible seam all the way down your sculpt.
Next comes the keys! Put wedges of clay all the way around your sculpture, about 3 or 4 inches apart. If you were doing a 2 part mold, you’d want these so that your mold would fit together easily and without you wiggling it around to find the right fit for it.
keys and final piece ready to mold
After you’ve got your walls in, cover what plaster/ultracal is exposed with vaseline. This will make sure that the plaster doesn’t bond to itself. If that happens, you’ve got a massive block of plaster that has clay sandwiched in it.
Next you want to create a beauty layer of your ultracal. Follow the directions you got with your ultracal, and mix it slightly more watery. Ultracal has a fairly slow set time, so this works in your favor. With that fine layer, brush it onto your sculpt as smooth as possible. Don’t let the brush scratch the sculpture, and if you don’t feel like using a brush for that reason, use your hands.
Once your beauty layer is done and you have a little more ultracal built up on top of that, move on to the strength of the piece! Ultracal is extremely hard, it won’t break easily. However, in between your layers of ultracal you should add something to strengthen it. Fine burlap or plaster gauze works well for this. I added plaster gauze, about two layers of it all around the head.
And once more for good measure! Mix up more ultracal, and slather this all over your mold. Be sure to flatten the top so that the mold can sit without rocking.
Leave that for 30 minutes to 1 hour, then pull them open! It’s not easy to pull this out of the mold, the suction will concern you. If you have problems, hammer a flat head screwdriver into the edges, be careful not to hurt your bust or your mold. If you use that screwdriver as a level all the way around the mold, it should pop out as long as you don’t have any undercuts.
Clean out your mold as best you can, a power washer works wonders. If you don’t have access to one of those, then just use a toothpick and time.