FX Foam (Flexible Foam) is an elastomeric polyurethane that when fully cured forms a tough abrasion resistant rubber foam. Parts made with this product have an integral rubber skin with an excellent cosmetic finish requiring almost no further processing. FX Foams are available in densities ranging from 6 lbs. to 26 lbs. per cubic foot. FX Foams are excellent for cosplay designers as well as prop makers.


  • 1 to 1 by Volume mixing ration for easy processing.
  • Excellent physical properties of the cured polymer.
  • Rapid Cure to enhance molding cycle times.


Molds for process FX Foam (Flexible Foam) must be able to withstand 10 -20 psi to properly produce an acceptable outer skin.

Ideal mold temperature 70°-80° F

Maintaining pressure on the curing part is critical to enable compaction of the foaming polymer against the surfaces of the mold to produce a skin.

Molds can be made of aluminum or rust free carbon steel. Johnson's paste release must be used to avoid bonding the polymer to the mold's surface.

Flexible silicone rubber molds may also be used with rigid outer container box.

Platinum-based Silicone rubber is preferred however tin-based silicone can be used if it is aged at 150°F for 3-4 hour before using. This drives off any alcohol that may be present in the mold's surface and could possibly cause problems with the surface finish.

Calculating the amount of liquid resin to use with the mold

1. Calculate the cubic inches of the mold.

2. Then divide cubic inches of foam produced per pound of mixed resin (see chart) to calculate the total amount of resin (A+B) lbs. to use to produce a part with an acceptable skin (lbs). This would be the ideal weight but always add 10-15% extra to improve the quality of the outer surface of the molded part.

Mix by weight is always better than by volume.
Weight into a clean plastic container 100 Parts of the Component A.

Weigh into the same container 94 Parts of Component B ( Pre-mix the Component B once each day before using)
Mix 15 seconds with a flat spatula for a small batch (Maximum of 2 lbs. of material) and electric drill and "Jiffy mixer" for larger batches (Maximum of 6 lbs. of material), taking care to scrape the sides and bottom of the container.

Pour into a new clean container mix again 15-20 seconds then pour into the mold.

Using two containers ensures that there is no unmixed material introduced into the mold which would cause "sticky" spots in the finished part.
Close the mold and allow the foam to rise and compress against the surface of the mold, hold 20 to 30 psi on the closed mold while the part is curing (about 30 minutes @ 72°F)

If the pigment is supplied separate use this procedure.
Weigh into a clean plastic container 94 Parts of the Component B and 2 parts of pigment. Blend together before adding the Component A. Add 100 parts of Component A and complete the mix as previously described.


Problem Solving




Sticky spots on part surface

A & B not thoroughly mixed

Use two containers for mixing.

The part has blisters that swell over time.

A & B not thoroughly mixed.

Use two containers for mixing.

Color is uneven

A & B not thoroughly mixed.

Use two containers for mixing.


Component B was not premixed.

Pre-mix Component B once each day.

Foam collapses

A & B not thoroughly mixed.

Use two containers for mixing.


Component B was not premixed.

Pre-mix Component B once each day.

The foam will not rise after mixing

Blowing agent has escaped.

Make sure Component B container lid is on tight when containers are stored.


Temperature too cold for processing.

Warm Component A & B and mold to 70°-100°F



Working Properties

Mix Ratio By Weight

100 parts A/ 94 part B

Mix Ratio By Volume

1 part A/ 1 parts B

Viscosity @ 72°F (A Side)

3109 CPS

Viscosity @ 72°F (B Side)

2600 CPS

Viscosity @ 72°F (Mixed)

2855 CPS


Part A:

Clear Amber


Part B:




White (without pigment)

*Other colors available upon request


Working Life 200 gram Mass 22°C (72°F)


Cream Time (Foam begins to rise)

1-1.5 minutes

Gel Time (Foam stops rising)

4-5 minutes

Demold Time (depending on part size)

30-45 minutes



Physical Properties

Specific Gravity: (Part A)


Specific Gravity: (Part B)


Specific Gravity: (Mixed)


Weight/Gallon Part A

9.22 lbs.

Weight/Gallon Part B

8.67 lbs.

Weight/Gallon Mixed

8.94 lbs.

Nominal Free Rise density

6-26 lb/cubic ft.

Cubic inch per lb. of product

66.46 in3 to 288 in3


Clean Up

Dispose of all empty FX Foam (Flexible Foam) component containers in accordance with local, state and federal regulations. Empty component containers can be rendered non-hazardous by rinsing the containers with a small amount of mixed material and allowing the solvents to evaporate. The containers will then contain non-hazardous cured urethane.

Storage and Shelf Life

FX Foam (Flexible Foam) containers should be stored in a cool dry area that is protected from direct sunlight and moisture. Storage temperatures should not exceed 80°F. The shelf life of factory sealed containers stored under these conditions is six (6) months.


Shipping Class: Class 55 Non-hazardous