PT Flex Series Casting Rubbers – New & Improved

PT Flex Fast-Setting Casting RubberPT Flex Series liquid rubbers are pourable polyurethane casting rubbers specifically designed for making prototypes as well as functional rubber parts. Unlike liquid polyurethane mold rubbers (for mold making), these castable rubbers are low in viscosity and are fast curing so they can be demolded rapidly.

New & Improved PT Flex Casting Rubbers no longer contain mercury. 


  • Wide range of rubber hardness (Shore A20 – D60)
  • Rapid demold times
  • Low-viscosity
  • Easy 1A:1B mix ratios
  • Low shrinkage on cure
  • Can be colored with PolyColor Dyes
  • Several accessories available to manipulate liquid rubber (e.g., accelerate, soften, thicken)


Typical Uses

  • Rapid prototyping
  • Model making
  • Quickly replicate 3D-printed parts
  • Decorative objects
  • Production parts and tools
  • Special effects
  • Props
  • Duplicate masters and patterns


Note: DO NOT mix “New & Improved” PT Flex rubbers with previous versions of PT Flex rubbers.

Product Options

Product Mix Ratio Shore Hardness Pour Time Demold Time @ Room Temperature Cured Color
PT Flex 20 1A:1B A20 4 min. 2 hr. Tan
PT Flex 50 – New & Improved  1A:1B A50 4 min. 2 hr. Yellow/Amber
PT Flex 60 – New & Improved 1A:1B A60 4 min. 2 hr. Yellow/Amber
PT Flex 70 – New & Improved  1A:1B A70 4 min. 2 hr. Yellow/Amber
PT Flex 85 – New & Improved  1A:1B A85 4 min. 2 hr. Yellow/Amber
PT Flex D60 2A:1B D60 10 min. 16 hr. Amber
Color Dyes PolyColor Dyes can be used to color PT Flex Series rubbers. They are available in Black, Brown, Blue, Green, Red, Yellow, and a White Pigment.
Softener Add Poly 74/75 Part C Softener to PT Flex products for a lower-viscosity mix and a softer rubber.
Accelerator Add Poly 74/75 Part X Accelerator to PT Flex products to accelerate the cure. This will also reduce the pour time.
Thickeners Use PolyFiber II or Fumed Silica to thicken the liquid mix for application by brush or trowel.
UV Stabilizer Use UV additive to help reduce the characteristic surface degradation caused by sunlight.
Product Life Extender Use Poly Purge Aerosol Dry Gas to extend product life by spraying it into containers before resealing.


Product Literature

“New & Improved” PT Flex Series Technical BulletinPT Flex Series Technical Bulletin (Older Versions)