Mold Making Rubber

Fairey & Company carries an extensive inventory of many different types of "rubbers" in liquid form, commonly used for mold making, each with specific pros and cons.  General Mold Making Information will get you started.

LATEX is the simplest and lowest cost of our mold making rubbers and the only true, natural rubber, sourced from gum rubber trees.  Latex is used directly out of the container, brushed onto your object like paint and releases from almost any surface without any release agent required.  However, latex requires 1-4 hours to dry between each coat and ten to twenty coats to build up a suitable mold thickness, so the result is a relatively slow mold-making process.  Latex also shrinks after curing, so is best suited for either smaller objects or where dimensional accuracy is not important.  The resultant mold, though, is a thin, very elastic glove-like mold.  For detailed instructions go to:  Latex Mold Making

POLYURETHANES are stocked in a wide variety of formulations, yielding harder or softer finished "rubbers", expressed as a "Shore A Durometer" value, ranging from 0 on the scale, which would be as soft as human flesh to 90 which would be similar to the hardness of the plug on an electrical cord.  Polyurethanes are two-component systems (mix Part A with Part B), most of them mixed in a simple 1 to 1 ratio by volume measure, and do require the application of a suitable release agent to your object to avoid permanent bonding.  Polyurethanes come ready-formulated in two consistencies; thickened, paste-like versions for brush-on applications (only 3 to 4 coats required) or very fluid versions for pouring into a contained area.  The material cost for a polyurethane mold will be higher than for latex, but much faster to make and the resulting mold will be tougher and longer lasting with virtually no detectable shrinkage.

SILICONES are the most versatile of the mold compounds we carry.  Silicones are also two-component systems (Part A + Part B), most of them requiring accurate weighing in the correct ratio.  Silicones will release from almost any surface without the need for a release agent and in use, almost nothing will stick to a silicone mold.  There are two basic varieties of silicones; tin-based and platinum-based.  Tin-based silicones are less costly, but platinums have the longest archival life.  The material cost for either type of silicone is higher than for either latex or polyurethanes, but in more demanding applications, such as resin or wax-casting, the mold life will be many times longer and easily justified.  Cross Reference Chart for POLYURETHANES & SILICONES

For a more detailed discussion of the pro's & con's of each of these materials, go to Moldmaking Material Selection.