Smooth Cast ONYX Slow

SKU: 799750

Size: Pint Kit
Sale price$38.89

unit(s) in Stock.


unit(s) in Stock.


unit(s) in Stock.

*Price and availability may vary.


Unit Size Net Weight
Pint Kit 2.2 lb
Gallon Kit 16.5 lb
Five Gallon Kit 82.5 lb



Smooth-Cast ONYX¨ SLOW is a mercury-free Ultra-Black urethane resin that cures quickly at room temperature to a deep black, solid plastic. Applications include reproducing sculpture, making prototypes and potting / encapsulation. Because ONYX¨ is a fast curing resin and becomes hard quickly, it is also great for doing fast cold cast bronze, brass, copper, nickel/silver, etc. ONYX¨ offers the convenience of a 1A:1B by volume mix ratio and has a very low viscosity, so it is easy to mix and pour. ONYX¨ has an ultimate shore hardness of 80D and offers higher physical properties and higher heat resistance vs. other general purpose resins.
Technical Properties
Mix Ratio by Weight 120A:100B
Mix Ratio by Volume 100A:100B
Pot Life 5 minutes
Cure Time 90 minutes
Color Black
Shore Hardness 80D
Mixed Viscosity 100 cps
Specific Volume 27.7 cu. in./lb.
Specific Gravity 1.09g/cc
Tensile Strength 7,660 psi
Elongation @ Break 3%
Compressive Modulus 97,900 psi
Tensile Modulus 374,000 psi
Flexural Strength 10,230 psi
Flexural Modulus 286,000 psi
Compressive Strength 11,400 psi
Heat Deflection Temp 212¼F


Advantages that ONYX¨ offers over other resins :
1) if you desire a black casting, adding color pigment is not necessary
2) cured plastic is ultra-black and darker than competitive black resins
3) cured ONYX¨ plastic can be polished and buffed to a high gloss shine
4) ONYX¨ offers higher heat resistance (to 200¡F /94¡ C at room temperature) vs. competitive black resins
5) unlike other black resins, ONYX¨does not contain mercury
6) ONYX¨ is less expensive vs. other black resins.
How do I remove release agent from my cured urethane casting if I want to prime or paint the casting?
Removing a silicone-based release agent from your cured urethane casting is not easy. The most effective way is to sand blast or bead blast the surface of your casting. However, sand blasting removes a micro thin layer of the castingÕs surface. If not done properly, you can damage or remove fine detail. Soap Wipe or brush the casting with a soap that has high alkali content. Cascade brand dishwashing gel is highly alkaline and also contains baking soda, which is an advantage. Solvents Wipe or brush the casting with Acetone, Toluene, Isopropyl Alcohol or Mineral Spirits.
Important: follow all safety precautions when using flammable liquids. You can then prime and paint your casting.
Special Order Items
The products listed below are currently SPECIAL ORDER items and require pre order.
Lead times may vary - For more information please contact our staff.

799752 - Smooth Cast ONYX Slow - Five Gallon Kit
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