How to Use Silicone Caulk Instead of Liquid Latex

Make molds with silicone caulk.

If you want to produce many replicas of a decorative element for your home, the best way to do it is with a mold. Liquid latex is the most commonly available mold-making material, but it is thin and takes dozens of layers to build up a mold of any strength. An alternative is to use silicone caulk, which is available at any hardware store. The caulk allows a mold to be made requiring only a few layers. This technique works well if the object you are molding has a flat base, such as a bust or candle holder.

Things You'll Need

• Object to be molded
• Hot glue
• Petroleum jelly
• Paintbrush
• Bucket
• 100 percent silicone caulk
• Razor blade
• Rubber gloves

Instructions

1. Secure the mold to a work surface hot glue.

2. Brush a thin layer of petroleum jelly to the entire object and surrounding work surface. You only need a micro-thin layer as a release agent. Be careful not to fill in any fine detail.

3. Fill a bucket halfway with water.

4. Hold your hand underwater and squeeze a large dollop of silicone caulk into it.

5. Form the caulk into a flat disk shape under the water's surface. The water will prevent the caulk from sticking to your hands.

6. Press the silicone disk into the object. It should be no thicker than a quarter-inch.

7. Add more silicone disks until the object is covered.

8. Allow the silicone to cure for several hours until it has hardened. Different caulks take different amounts of time; consult the label for your caulk's curing time.

9. Add a second layer of silicone caulk disks, pressing them into the first layer. Allow the caulk to cure, then add a third layer.

10. Remove the object from the mold once the silicone has cured. If it cannot simply pull out, cut a slit up the mold's back side with a razor blade until it can peel off of the object.

Tips & Warnings

• The layers must be thin because silicone caulk cures through contact with air.

• Wear rubber gloves when handling uncured silicone caulk.

References

• "The Prop Builder's Molding & Casting Handbook"; Thurston James; 1989
• My Heap: Silicone Caulk Molds