How to Use Latex for Molds

Latex can be used for more than gloves.

You can make a mold of small objects such as rocks and toy cars with liquid latex, a natural rubber product that is available in most hobby shops. These molds can be used to create reproductions of the original object. Molds are useful when many copies of an object are required. For example, you can mold an interesting rock and create a field of boulders in a model train landscape.

Things You'll Need

• Acrylic enamel spray
• Liquid latex
• Cheap paint brush
• Hair dryer
• Cheesecloth or gauze
• Plaster bandages (optional)
• Scissors (optional)
• Hairdryer (optional)
• Modeling clay (optional)

Instructions

1. Spray the object with two thin coats of acrylic enamel spray to seal the surface. Allow the first coat to dry completely before applying the second.

2. Apply a thin coat of liquid latex to the surface of the object with a cheap paint brush. Work the latex into any nooks and crannies.

3. Allow the latex to dry. This will take only a few minutes, and can be sped up with a hair dryer.

4. Brush on 7 more layers of latex, allowing each one to dry completely before applying the next.

5. Brush another layer of latex onto the mold, then press a piece of cheesecloth or gauze into it to increase the mold's strength. Brush more latex into the cloth, fully saturating it. Remove any air bubbles that become trapped by squeezing them out with the bristles of the brush.

6. Allow the mold to dry. This can take anywhere from one to three hours.

7. If the object is small, peel the mold off. The latex will be stiff enough to hold its shape. If it is larger, continue to the next step before removing the mold.

8. Cut plaster bandages into strips. The size will depend on the object being molded.

9. Cover the mold in four layers of plaster bandage strips, each one dipped in water before being applied. Apply the second layer immediately after the first, while the first is still wet. Repeat for the third and fourth layers. The bandages will form a shell that will help the latex mold to keep its shape.

10. Allow the bandages to dry.

11. Pull the shell off of the mold. It will still be thin enough to flex slightly if needed. Remove the mold from the object and place it back into the shell.

Tips & Warnings

• Liquid latex dries through contact with air. Each layer must be thin to prevent a skin from forming, which would keep the latex underneath from drying.

• Wrap the paint brush in plastic wrap after applying each layer to prevent the latex in the bristles from drying. If it dries, the bristles will be ruined and you will have to use a new brush.

• Fill any holes passing through an object with modeling clay. If you do not, the mold will not be able to come off of the object.

References

• Model Train: Latex Mold Making
• "The Prop Builder's Molding & Casting Handbook"; Thurston James; 1989