Polytek

Liquid Mold Rubbers

liquid-mold-rubbersYour choice of mold material is based primarily upon which casting material you plan to use and how many castings you wish to produce.

Polyurethane mold rubbers are excellent for casting concrete, plaster, wax and limited resins and are very economical.

Silicone mold rubbers are the best choice for reproducing numerous resin castings (polyurethane, polyester, epoxy) and polyurethane foam parts. Silicones are more expensive, but have greater chemical resistance and longer mold life when resin casting. Both tin-cured and platinum-cured liquid silicones are available.

Latex mold rubbers are used primarily to create molds for casting decorative concrete statuary and are generally less popular due to the length of time required to make the mold.

Polyurethane and silicone rubbers are most popular as molds can be completed within a day!

For further assistance in selecting a mold material, visit our “Help Me Select a Mold Material” page.

 

General Information

Rubber Type Advantages Disadvantages Casting Materials Methods
Polyurethane Mold Rubbers High Strength, low to moderate cost, many versatile formulas. Requires careful application of release agent, moisture sensitive (in liquid form). Many materials, including concrete, plaster, and wax. Acceptable for some resins. Not acceptable for molten metals. Pour, Brush, Spray.
Platinum-Cured Silicone Mold Rubbers No release agent needed for most casting applications, no shrink on cure, cured rubber has long storage life, high strength, excellent chemical resistance. Higher cost, cure inhibited by some surfaces. Most materials, especially resins, foams and some low-melt metals. Pour, Brush, Spray.
Tin-Cured Silicone Mold Rubbers No release agent needed for most casting applications, high strength, excellent chemical resistance. Higher cost, shrinks on cure (~1%), cured rubber has limited storage life. Most materials, especially resins, foams and some low-melt metals. Pour, Brush, Spray.
Latex Mold Rubber High strength, one-part system. Dimensionally unstable, takes days or weeks to make a mold, oils can soften and destroy molds, makes only blanket molds, which require mold shells. Concrete, plaster, limited resin casting. Brush, Spray, Dip.
For assistance in selecting a mold material: – Call: 800.858.5990 | Email: sales@polytek.com | Online Contact Form