ilicone mold rubber is generally known for its excellent release properties and does not stick to most surfaces. However, it can adhere to materials with open pores (like open-grain wood, very dry plaster, or concrete). It may also bond with glass, surfaces coated with shellac, or even itself, which can be useful when adding new silicone to a cured mold.
Here are some tips for sealing a model before applying silicone:
- Acrylic Spray: This can effectively seal the surface.
- Petroleum Jelly thinned with Mineral Spirits: Apply carefully to avoid leaving brush strokes, as these will be visible on the mold surface once the silicone is applied.
- Wax: Similar to petroleum jelly, apply carefully to avoid brush strokes.
- Avoid Alcohol: Do not wipe the model with alcohol before applying silicone rubber, as it may affect adhesion.
- Do Not Use Shellac: Shellac contains alcohol, which can cause the rubber to bond to the model.
- Avoid Silicone-Based Release Agents: These can sometimes act as a bonding primer for the silicone rubber.
If there’s any uncertainty about the compatibility of a sealer or release agent, it’s always a good idea to conduct a small test on a non-critical piece first.