Elkem Silicone HCRA 4550 50A (HCR) High Consistency Rubber (A-4550-HCRA)

A-4550-HCRA Silicone Gum (Heat Cure HCR, Shore A 50)

A-4550-HCRA is a platinum-cure, high consistency rubber (HCR) silicone gum offering an excellent balance of strength, flexibility, and workability. With a Shore A 50 durometer, it provides a slightly softer alternative within the HCRA series while maintaining strong mechanical performance and durability.

HCR silicones are supplied in a gum form, allowing technicians to sculpt, shape, and laminate directly into the material prior to cure. This makes them ideal for applications requiring hands-on fabrication and precise control.

The material is dimensionally stable with minimal shrinkage and bonds well to a variety of substrates. It also features an extended working time of up to 6 hours (at ~65°F), allowing ample time for processing before cure. Final curing is achieved through heat.

Product Features

• Shore A 50 silicone gum for balanced flexibility and strength

• Platinum-cure (addition cure) system

• High consistency (gum) form for sculpting and shaping

• Excellent mechanical properties

• Low to no shrinkage for dimensional stability

• Bonds well to multiple substrates for lamination

• Long working time (~6 hours at 65°F)

• Heat cure required

Processing Notes

• Supplied as a two-part system (Part A & Part B)

• Mix equal parts thoroughly prior to use

• Two-roll mill required for proper blending and pigment incorporation

Typical Applications

• Sculpted silicone components

• Laminated silicone structures

• Applications requiring durability with added flexibility

Physical Properties (Typical)

• Durometer (Shore A): ~50 (range 45–55)

• Tensile Strength: up to ~1900 psi

• Elongation: up to ~1000%

• Tear Strength: up to ~320 lb/in

• Appearance: Clear

A versatile HCR silicone designed for fabrication, sculpting, and applications requiring a balance of strength and flexibility.