How to Make a Plaster Mold
- Make sure the container is clean before filling the container ¾ full of water.
- Add teaspoons of plaster powder to the water in the milk carton sifting it evenly. Continue until there is a "little mountain" that rises in the middle. Sprinkle in a few more teaspoons around the sides.
- Stir the mixture slowly with the stick without lifting it from the carton to keep as many air bubbles out as possible. Check the stick several times to see if any lumps appear at the end of it. Stop when the stick shows only a smooth, stirred mixture.
- Use the stick to swat the container on the outside from the bottom upward many times to release air bubbles. You can see them popping.
- Set containers aside to harden.
After the plaster has been removed from the carton, start carving it with a knife. I like to use a "fettling" knife, usually used in ceramics, because of its size and flexibility.
At this stage, the block is very damp. Large chunks of material can be easily removed. It's important to keep "connectivity" in mind, and carve areas from side to side.
There is only 1 requirement for this first undertaking. The sculpture had to be "open", that is, you can see through it, unless a specific solid shape was desired. Students are encouraged to draw lines on the sculpture in pencil, and move them across all the sides of the block in some way.
Once "lines" have been drawn and cut around the block, students were encouraged to "lose" the corners, rounding off some of the edges--but a little at a time. One must remember: once the shape it cut, that piece is gone forever.
Little by little, we understood how to make shapes come forward (by cutting away whatever is around it,) or recede (by cutting it back). The left block shows this very nicely, especially on the right side.
Texture incised into special interior and exterior areas of this form greatly added interest and contrast to its smoothed surface.
The texture is added after the form has been successively sandpapered from medium to fine in a dry state. With an etching tool, ceramic needle, carpentry nail, dentist tool, leadless lead pencil, etc., very fine lines can be incised into the surface. They should be deep enough to withstand 2 more finishing techniques.
Should the textures lose some desired depth, they can be recut when the final sanding process has been done.