Tips for using silicone caulking for making a mold

1. Use a brush to spread the silicone in very thin layers on the model. This will force out any small air pockets that may be trapped in it.
2. When making coats of silicone, latex or whatever, brush each coat in a different direction than the last. This will create a stronger mold from different grain directions.
3. Continue this process until the silicone is built up enough to be somewhat rigid, say a quarter of an inch. fill the rest of the form with a hard setting backing. Resin, liquid fiber glass, plaster, etc.
4. Repeat the process with the other side of the mold.

How to create a pull away mold (Slip Mold)

1. Attach the item to a piece of styrene or Plexiglas.
2. Paint layers of latex on the model, extending it an inch or so away from the model onto the styrene..
3. Continue painting layers as described earlier until you have an eighth inch or so of latex built up.
4. Pull latex from model covering it with talcum powder as you go. The talcum powder prevents the latex mold from sticking to itself.
5. To cast using the pull away mold, cut a hole in a box large enough to set the mold in, but small enough for the lip of the mold to rest on the box.
6. Pour and pull latex slip mold from casting.

Release agents

1. Vaseline thinned with Naptha (lighter fluid) can be used as a release agent on silicone. The ratios very. I have used 10:1 (Naptha:Vaseline) and applied it with a spray bottle.
2. Soapy water (8 oz. water and a few drops of liquid soap) can be used as a release agent on clay for making plaster molds. Additionally, I spray it in RTV molds that I cast plaster in to help reduce the number of air bubbles seen on the surface.

Parting line fillers

1. Soft wax can be used to create a mold line and can be melted away with a light bulb.

Thinning Silicone Caulk

1. Sources on the internet indicate that Distilled water, Naphtha, Toloul or charcoal lighter fluid can be used to thin silicone caulk in a tube. One suggestion was to mix 50:50 Naphtha : Silicone Caulk to about the consistency of honey and paint on. These need to be tested.