Comparing With Polyurethane and silicone

Type                        Advantages                         Disadvantages

Polyurethanes                High strength                          Requires careful application of release agent

                                Low to moderate cost                    Moisture sensitive (in liquid form)

                                Many versatile formulas

Tin-Cured Silicones         No release agent needed                   Higher cost

                                High strength                             Shrinks on cure (~1%)

                                Excellent chemical resistance             Cured rubber has limited storage life

Platinum-Cured silicones    No release agent needed                   Higher cost

                                No shrink on cure                         Cure inhibited by some surfaces

                               Cured rubber has long storage life

                               High strength

                               Excellent chemical resistance