Formlabs Silicone 40A Resin is a breakthrough 100% silicone material, perfected for Formlabs’ SLA 3D printers using their Pure Silicone Technology™. Possessing an impeccable blend of properties like unmatched elasticity, formidable chemical resistance, and superior thermal stability, this dark grey material is primed for diverse applications such as industrial seals, wearables, medical device components, and more. While its biocompatibility for skin contact remains under evaluation, the resin’s flexibility, resilience, and aesthetic appeal hold great promise for professionals across various sectors.

Physical Properties

  • Ultimate Tensile Strength: 5 MPa or 725 psi (ASTM D 412-06 Type C, 500 mm/min)
  • Elongation at Break: 230% (ASTM D 412-06 Type C, 500 mm/min)
  • Tear Strength: 12 kN/m or 68 lbf/in (ASTM D 624-00, Type C)
  • Stress at 50% Elongation: 0.4 MPa or 58 psi (ASTM D 412-06 Type C, 500 mm/min)
  • Stress at 100% Elongation: 1 MPa or 145 psi (ASTM D 412-06 Type C, 500 mm/min)
  • Stress at 150% Elongation: 2.1 MPa or 305 psi (ASTM D 412-06 Type C, 500 mm/min)
  • Compression Set: 20% after 22 hours at 23°C (ASTM D 395-03 (B))
  • Bayshore Resilience: 34% (ASTM D2632)
  • Ross Flexing Fatigue: > 500,000 cycles at both 23°C and -10°C (ASTM D1052)
  • Shore Hardness: 40A (ASTM 2240)
  • Glass Transition Temperature: -107°C or -161°F (ASTM D4065)
  • Viscosity: 7800 cP at 35 ºC

Aesthetic Quality

The material comes in a dark grey color and produces prints with a high-quality, smooth surface finish. Its ability to capture intricate details makes it highly suitable for both functional and aesthetic applications.

Durability and Usage

Silicone 40A Resin is optimized for applications requiring high thermal and chemical resistance, as well as excellent tear strength and rebound resilience. It is ideal for:

  • Seals, gaskets, and connectors in industrial and automotive applications
  • Wearables, grippers, and consumer goods prototypes
  • Medical device components, patient-matched prosthesis, and audiology applications
  • Soft and flexible fixtures and casting molds for repeated use


Specific post-processing steps would depend on the guidelines provided by Formlabs. However, typical steps include washing in a suitable solvent to remove uncured resin, followed by post-curing, if necessary.


The material is currently being evaluated for skin contact applications according to various ISO standards, including ISO 10993-5:2009, ISO 10993-23:2021, and ISO 10993-10:2021. The data is pending.

Environmental Impact

Silicone-based materials generally have a lower environmental impact compared to some other synthetic materials but are not biodegradable. Special disposal methods may be required.

In summary, Formlabs Silicone 40A Resin offers a highly specialized material with exceptional elasticity, chemical resistance, and thermal stability. While biocompatibility data is pending, its versatility and excellent mechanical properties make it ideal for a wide range of applications, from industrial seals to medical devices.

Formlabs Silicone 40A – Technical Data Sheet