ForMatter/Materials/polymer/Silicone Rubber (RTV)
mat_silicone

Silicone Rubber (RTV)

elastomer, thermoset · silicone, PDMS, RTV silicone, polydimethylsiloxane
mediumlast updated 2026-04-26
metallic 0.00
hue shift +0°

The rubbery, slightly squishy material of phone cases, kitchen spatulas, gaskets, and prototype-shop mold-making. Pours as a liquid, cures into a flexible solid in hours at room temperature. Heat-resistant well beyond what other rubbers can take.

Polymer with a silicon-oxygen backbone (siloxane), distinct from carbon-backbone elastomers. Room-temperature-vulcanizing (RTV) grades cure via tin or platinum catalysis. Excellent thermal stability (-50 to +250 °C), inert, biocompatible (medical-grade platinum-cured), poor adhesion (an asset for mold-release).

mechanical

  • tensile_strength_mpa7
  • elongation_pct400
  • hardness_shore_a30
source: Smooth-On Mold Star 30 datasheet (representative)

thermal

  • service_range_c-50 to 250
  • thermal_conductivity_w_mk0.2
source: Smooth-On

Sustainability

  • embodied carbon kg co2e per kg5.5
  • sourceEditorial estimate from ICE / Granta CES EduPack class databases — industry mean, with cradle-to-gate boundary unless otherwise noted. Embodied carbon for any specific product depends on supplier mix, recycled content, and energy grid; verify against a primary source before using these numbers in a sustainability claim.
  • recyclabilitylow — thermoset, cannot be remelted; some grinding-and-reuse as filler
  • biodegradableFalse
  • certificationsUSP Class VI (medical-grade, platinum-cured)
visual
translucent in unpigmented form, accepts bright colors when dyed
tactile
soft, slightly sticky, drags against itself, slips against most other surfaces
weight perception
light
acoustic
silent on impact — the material used to deaden sound in many products

PBR starter values

Principled BSDF defaults derived from the sphere matte finish. Reasonable seed for Blender, Substance, Keyshot, Rhino — tune per material.

# finish:      matte
albedo        #e0d8d0
metallic      0.00
roughness     0.75
ior           1.45
transmission  0.00
clearcoat     0.00
sheen         0.00
anisotropic   0.00
copy as JSON 
{
  "albedo": "#e0d8d0",
  "metallic": 0.0,
  "roughness": 0.75,
  "ior": 1.45,
  "transmission": 0.0,
  "clearcoat": 0.0,
  "sheen": 0.0,
  "anisotropic": 0.0
}
Blender 4.x Python 
# Blender 4.x — Principled BSDF
# Silicone Rubber (RTV) · finish: matte
import bpy
mat = bpy.data.materials.new(name="mat_silicone")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value         = (0.7454, 0.6867, 0.6308, 1.0)
bsdf.inputs["Metallic"].default_value           = 0.000
bsdf.inputs["Roughness"].default_value          = 0.750
bsdf.inputs["IOR"].default_value                = 1.450
bsdf.inputs["Transmission Weight"].default_value = 0.000
bsdf.inputs["Coat Weight"].default_value        = 0.000
bsdf.inputs["Sheen Weight"].default_value       = 0.000
bsdf.inputs["Anisotropic"].default_value        = 0.000
KeyShot Python (lux) 
# KeyShot 11+ — lux Python API, Generic material
# Silicone Rubber (RTV) · finish: matte
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_silicone", materialType="Generic")
mat.setProperty("diffuse",      (224, 216, 208))   # 8-bit sRGB
mat.setProperty("metallic",     0.000)
mat.setProperty("roughness",    0.750)
mat.setProperty("indexOfRefraction", 1.450)
mat.setProperty("transparency", 0.000)
mat.setProperty("coatingWeight", 0.000)
Substance pbrMetalRough 
{
  "_format": "Substance Designer / Painter \u2014 pbrMetalRough constants",
  "_about": "Silicone Rubber (RTV) \u00b7 finish: matte",
  "baseColor": {
    "r": 0.7454,
    "g": 0.6867,
    "b": 0.6308
  },
  "metallic": 0.0,
  "roughness": 0.75,
  "ior": 1.45,
  "opacity": 1.0,
  "anisotropyLevel": 0.0,
  "_notes": "Channels listed are the standard Substance pbrMetalRough output. Drop into a Uniform Color node per channel, or as the constant input on a layered stack."
}
glTF 2.0 Metallic-Roughness 
{
  "asset": {
    "version": "2.0",
    "generator": "ForMatter"
  },
  "materials": [
    {
      "name": "mat_silicone",
      "pbrMetallicRoughness": {
        "baseColorFactor": [
          0.7454,
          0.6867,
          0.6308,
          1.0
        ],
        "metallicFactor": 0.0,
        "roughnessFactor": 0.75
      },
      "extensions": {
        "KHR_materials_ior": {
          "ior": 1.45
        }
      }
    }
  ]
}
USD Preview Surface 
# USD Preview Surface — UsdShade.MaterialLook prim attributes
# Silicone Rubber (RTV) · finish: matte
def Material "mat_silicone" {
    token outputs:surface.connect = </mat_silicone/PreviewSurface.outputs:surface>

    def Shader "PreviewSurface" {
        uniform token info:id = "UsdPreviewSurface"
        color3f inputs:diffuseColor = (0.7454, 0.6867, 0.6308)
        float   inputs:metallic     = 0.000
        float   inputs:roughness    = 0.750
        float   inputs:ior          = 1.450
        float   inputs:opacity      = 1.000
        float   inputs:clearcoat    = 0.000
        token   outputs:surface
    }
}
↓ download glTF material
ProcessInjection Molding · Adhesive Bonding
Used inEyewear Frame · Prototype / Concept Model

Citations

  • datasheet · Smooth-On Mold Star 30 technical bulletin