FormRub Series Liquid Mold Rubbers

Use FormRub Series liquid polyurethane rubbers to make high-performance molds that stand up to the rigors of high-production casting and forming of concrete.

These liquid rubbers are two-part systems that cure at room temperature and can be demolded from original models after ~16 hours. All FormRub product options have simple, 1A:1B mix ratios and are low-viscosity mixes that flow easily across detailed models.

In addition to concrete, FormRub molds are often used to cast plaster and wax. With use of an appropriate release agent, some resins and foams can also be cast in FormRub molds.


  • Shore A35 to A65 hardness mold rubbers
  • Low viscosity
  • 1A:1B mix ratios
  • High-strength, abrasion-resistant, long-lasting molds
  • Reproduces fine details
  • Pourable or brushable (see “Thickeners” under “Accessories” for brushing)
  • Can be accelerated for rapid cure
  • Economical & versatile
  • Ideal for the most demanding mold making applications
  • All rubbers can be demolded after ~16 hours


Typical Uses


Product Options

Product Mix Ratio Shore Hardness Pour Time Cured Color
FormRub 35
1A:1B A35 15 min. Turquoise
FormRub 50 1A:1B A50 10 min. Opaque Orange
FormRub 60 1A:1B A60 22 min. Opaque Off-White/Tan
FormRub 65 1A:1B A65 35 min. Clear Yellow/Amber
Softener Add Poly 74/75 Part C Softener to FormRub Series products for a lower-viscosity mix and a softer rubber.
Accelerator Add Poly 74/75 Part X Accelerator to FormRub Series products to accelerate the cure.
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.
Reinforcement Materials for Blanket Molds Use Tietex® Fabric to reinforce blanket molds.
Product Life Extender Use Poly Purge Aerosol Dry Gas to extend product life by spraying it into containers before resealing.


Product Literature

FormRub Series Technical Bulletin | FormRub Series Physical Properties

Video Tutorial

How to Make a Concrete Log Mold [FormRub 35 Liquid Rubber]