PureCast 604 is a two component liquid castable polyurethane elastomer that contains no TDI or MOCA. The material when cured has outstanding physical properties, exhibiting high tensile and tear strength along with exceptional abrasion resistance. It is insensitive to typical environmental moisture and exhibits low shrinkage. PureCast 604 provides the strength and durability of a heat-cured urethane in a simple to use RTV system. It provides you with the ability to cast high strength, flexible urethane parts in urethane or silicone molds. PureCast 604 can be colored with our RV series pigments. We recommend using black or darker colors to prevent color change or applying a UV resistant coating. The product is reddish/brown in color.

Application and Mix Ratio

Rope Coating Procedure

PureCast 604 component A (resin) and component B (curative) should be warmed to 100°F before mixing to reduce viscosity and decrease mixing.

The first coat should be thinned with toluene to further reduce the viscosity and increase penetration into the outer layer of the rope. The following formulation should be used:




PureCast 604 component B (curative)

100 grams


100 grams

Black pigment (special)

20 grams





PureCast 604 component A (resin)

400 grams


Mix with a flat metal spatula then transfer mix to a clean container and mix again, then apply by hand with protective latex gloves, pressing the polymer into the rope fiber. Before applying the second coat, wait 45 minutes and then apply with the same mixture ratio as first coat EXCEPT NO TOLUENE.

Before applying the third coat, wait 45 minutes and then apply with the same mixture ratio as first coat EXCEPT NO TOLUENE.


Working Properties

Mix Ratio By Weight

100 parts A/ 25 part B

Mix Ratio By Volume

100 parts A/ 26 parts B

Viscosity @ 72°F (A Side)

7,000 CPS

Viscosity @ 72°F (B Side)

100 CPS

Viscosity @ 72°F (Mixed)

3000 CPS



Clear to Clear Amber

Working Life @ 72°F

15-25 minutes

Demold Time* @72°F

16-24 hours

Demold Time* @150°F

2-4 hours

Complete Cure Time* @ 72°F

7 days

Complete Cure Time* @ 150°F

18 hours

* Set time and Demold time depends on temperature and relative humidity.


Physical Properties

Specific Gravity (Part A)


Specific Gravity (Part B)


Specific Gravity (Mixed)


Weight/Gallon Part A

8.59 lbs.

Weight/Gallon Part B

8.36 lbs.

Weight/Gallon Mixed

8.50 lbs.

Hardness @ 72° F

ASTM 2240-85

40-50 Shore D

Tear Strength

ASTM D-624 die C

1400 lb./in.

Tensile Strength

ASTM D-412 die C

5500 psi


ASTM D-412 die C




Although this coating will cure at lower temperatures, better results can be obtained by curing at elevated temperatures. Wait one hour after final coat and begin elevated curing at 120°F over night or 70°F or above for three days for full cure.

Clean Up

Dispose of all empty PureCast 604 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

PureCast 604 is shipped from the factory in sealed containers. The 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 the factory sealed containers stored under these conditions is six months. Containers that have been opened should be resealed immediately after material has been removed in order to prevent solvent evaporation.


Shipping Class: Class 55 Non-hazardous