380 Silicone Rubber

From: £28.06

Grade 380 is the medium, all-purpose grade of Sylmasta Silicone Rubber. It is stiffer than Grade 370 for better dimensional stability

SKU: 380 Category:


Grade 380 is the medium all-purpose grade of Sylmasta high tear strength moulding rubber for producing moulds used in the casting of polyurethane resins.

When set, Grade 380 is stiffer than Grade 370 which gives it better dimensional stability. Sylmasta Moulding Rubbers are produced to the highest standards for use in industry and model making to produce flexible, highly detailed rubber moulds of all sizes.

The high-quality of Sylmasta silicone rubbers means that once a mould has been taken from the master, it can be used again and again to pour multiple castings using Sylmasta PU Casting Resins.

Moulds made from Sylmasta Moulding Rubber have low shrinkage with no distortion and good dimensional stability. The long pot life means that there is plenty of time to pour the rubber and allow air bubbles to disperse.

Each pack of 380 Silicone Rubber contains catalyst and comes with a free reusable pipette, mixing cup and stirrer. You can order additional accessories from our Casting & Mould Making Accessories section.

Sylmasta casting resins have been trusted by professional kit builders and industrial users for years for their high detail and repeatability.


“Grade 380 Silicone Moulding Rubber has just the right degree of strength and flexibility for making small, highly detailed parts.” – Dr Alex Clark, author of Small Scale Modelling Masterclass


380 Silicone Medium Moulding Rubber details:

  • Pot Life: 45-120 minutes
  • De-mould time: 8 hours
  • Mixed viscosity: 16,500 mPa-s
  • Shore A hardness: 18°
  • Elongation at break: 539%
  • Tensile strength: 3.11 mPa
  • Tear strength: 23.49 kN/m
  • Young’s modulus: 1.18 mPa
  • Linear shrinkage: 0.39% min.
  • Service temperature: -50°C max.
  • Service temperature: 200°C
  • Colour when mixed: Pale blue

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