DIY Pour Foam Molds
Two-part plaster molds work well for creating molded foam objects because the two pieces of the mold are strapped together during the pouring process. Once the foam is poured, the foam expands, and pushes at both sides of the mold as the piece dries. The artist straps the finished mold together using heavy duty rubber bands or ceramic straps. The straps on the molds keep the pieces from separating. The finished piece is decorated using paint and sealants. Creating a two-part plaster mold for poured foam is a simple task, but the drying process takes a little bit of time.
Things You'll Need
- 2 identical cardboard boxes 2 inches wider, longer and taller than the original object
- Play sand
- Original object you want molded
- Modeling clay or ceramic clay
- Rolling pin
- Large marble or ball peen hammer
- Large plastic bowl or bucket
- Water
- Plaster
- Mixing spoon or stick
- Masking tape
- Sheet rock ripper
- Paper towels
Instructions
-
Making the First Half of the Mold
-
1
Place the box on a flat surface with the open top facing up. Fill the bottom of the box a little less than half full of sand.
-
2
Push the original object you want molded into the sand. You want almost half of it covered in the sand.
-
-
3
Roll a piece of clay into a cone shape with the wide end three inches wide. Make the narrow end of the cone one inch wide.
-
4
Push the sphere into the sand, so the narrow end of the cone presses against the widest part of the original object. If the wide end of the cone doesn't reach the side of the box, add more clay, and increase the size of the cone. This is where foam is poured into the finished mold.
-
5
Roll the clay into a flat sheet on a flat surface using the rolling pin. Tear off pieces of the flat sheet of clay, and make a flat layer of clay over the sand in the box. Seal the edges of the clay to the sides of the box and the original object. When you finish you only see clay and the object in the box instead of the sand.
-
6
Press the marble half way into the clay about an inch away from each corner, or press the rounded end of a ball peen hammer about 1/2 inch into the clay in the same spots. Pull it out, so it leaves a small indentation. These dents are registration marks that make lining up the parts of the mold easier after it dries.
-
7
Rub a thin coat of petroleum jelly over the original object parts that remain visible. Make sure you get it into any crevices or patterned areas, or the plaster will stick.
-
8
Mix the plaster according to the manufacturer’s instructions, and pour the plaster over the clay. Let it dry overnight.
-
9
Remove the box by tearing apart the glued edge with your fingers. The sand spills out of the bottom as you work, so it is messy. Carefully lift the plaster and the object without removing the object from the plaster.
-
10
Place the plaster in the second box with the flat side facing down. The object you are molding faces up. Make sure the clay sphere is still attached. Gently, pull off the rest of the clay while leaving the sphere in place.
-
11
Coat everything in the box that is facing up with petroleum jelly. Make sure there is a thin coat across the plaster and the object you are molding.
-
12
Mix another batch of plaster according to the manufacturer’s instructions. Pour the plaster into the box. Fill the box to the top, and let it dry overnight.
-
13
Tear off the box, and set the plaster mold on a flat surface. Try lifting the top piece of plaster off of the molded object. If it sticks, cut the line where the two pieces of plaster meet all the way around the mold with a sheet rock ripper, and then open the mold. Plaster molds usually stick, so make sure you have the sheet rock ripper on hand.
-
14
Lift the original object out of the mold. Pull a little harder if it sticks. Wipe off any excess petroleum jelly with a paper towel.
-
15
Put the top part of the mold back on, and let it dry with the two parts together overnight. That makes sure the mold is dry enough for use, and makes the two parts expand and contract evenly. Moisture sometimes warps molds. After it dries overnight, it is ready for use.
-
1
References
- Photo Credit Brand X Pictures/Brand X Pictures/Getty Images
