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Key Differences
| Product Type |
|
|
| Mixed Viscosity | 1,800 cps | 100 cps |
| Pot Life | 30 minutes | 5 minutes |
| Cure Time | 16 hours | 90 minutes |
| Shore D Hardness | — | 80 |
| Shore A Hardness | 30 | — |
| Color | Clear Amber | Black |
| Tensile Strength | 400 psi | 7,660 psi |
Disclaimer
Although we do our best to ensure accuracy, Smooth-On offers no warranties, promises, and/or representations of any kind, either expressed or implied, as to the accuracy, completeness, or reliability of the information contained on this Compare Tool, nor suitability of the information contained herein to your particular circumstances. Smooth-On assumes no liability for losses or damages of whatever nature (direct, indirect, consequential or other) associated with your use, or inability to use, the Compare Tool, or from your use (or failure to use) the information contained herein. Other useful tools include product technical bulletins and our extensive FAQ section. You can also contact our technical support team.All Technical Data
| PMC™-121 30/DRY | Smooth-Cast™ ONYX™ SLOW | |
|---|---|---|
| Product Type |
|
|
| Mixed Viscosity | 1,800 cps | 100 cps |
| Mix Ratio By Volume | 1A:1B | 100A:100B |
| Mix Ratio By Weight | 1A:1B | 120A:100B |
| Pot Life | 30 minutes | 5 minutes |
| Cure Time | 16 hours | 90 minutes |
| Shore D Hardness | — | 80 |
| Shore A Hardness | 30 | — |
| Specific Gravity | 1.04 g/cc | 1.09 g/cc |
| Specific Volume | 26.7 cu. in./lb. | 27.7 cu. in./lb. |
| Color | Clear Amber | Black |
| Die C Tear Strength | 75 pli | — |
| Tensile Strength | 400 psi | 7,660 psi |
| Tensile Modulus | — | 374,000 psi |
| Elongation @ Break | 1,000 % | 3 % |
| 100% Modulus | 82 psi | — |
| Compressive Strength | — | 11,400 psi |
| Compressive Modulus | — | 97,900 psi |
| Flexural Strength | — | 10,230 psi |
| Flexural Modulus | — | 286,000 psi |
| Shrinkage | < .001 in. / in. | 0.012 in. / in. |
| Heat Deflection With Post Cure | — | 212 °F |
Product Description
PMC™-121 30/DRY
The PMC™-121 Series urethane rubbers feature convenient one-to-one by volume mix ratios. PMC™-121/30 Dry is exceptionally strong and abrasion resistant for soft urethane mold rubbers. It does not exude oil and can be used for casting waxes, Smooth-On liquid plastics, gypsum plasters and other materials.
Smooth-Cast™ ONYX™ SLOW
Smooth-Cast™ ONYX™ is a mercury-free urethane resin that cures at room temperature to a deep black, solid plastic. ONYX™ resins offer the convenience of a 1A:1B by volume mix ratio and have very low viscosities, so they are easy to mix and pour. ONYX™ resins have an ultimate Shore hardness of 80D and offer higher physical properties and higher heat resistance vs. other general purpose resins. ONYX™ resins are available in 2 speeds. ONYX™ SLOW resin has a pot life of 5 minutes and a cure time of 90 minutes.