Smooth Cast 305

Unit Size	Net Weight
Pint Kit	1.9 lb
Gallon Kit	15.4 lb
Five Gallon Kit	77 lb

 

Smooth-Castª 305 is a medium-setting urethane casting resin which has an ultra-low viscosity and yields castings that are bright white and virtually bubble free.

Technical Properties

Mix Ratio by Weight	100A:90B
Mix Ratio by Volume	1A:1B
Pot Life	7 minutes
Cure Time	30 minutes
Color	White
Shore Hardness	70D
Mixed Viscosity	80 cps
Shrinkage	0.0065 in./in.
Specific Volume	26.4 cu.in./lb.
Specific Gravity	1.05g/cc
Tensile Strength	3,000 psi
Elongation @ Break	7.5%
Compressive Modulus	44,900 psi
Tensile Modulus	134,000 psi
Flexural Strength	4,000 psi
Flexural Modulus	118,000 psi
Compressive Strength	3,800 psi
Heat Deflection Temp	120¼F

 

Series liquid plastics are ultra-low viscosity casting resins yielding castings that are bright white and virtually bubble free. Vacuum degassing is not necessary. They offer the convenience of a one to one mix ratio (one part A to one part B by volume). The differences between them are pot life and demold time.
These resins readily accept fillers (such as URE-FIL 3 from Smooth-On) and can be pigmented (SC325 Series will achieve true color representation better than the SC305 series). Fully cured castings are tough, durable, machinable and paintable. They resist moisture and mild solvents.
Applications for Smooth-Cast Liquid Plastics include reproducing small to medium size sculptures, cold cast bronze castings, making prototype models, special effect props and decorative jewelry. Those interested in making roto cast pieces should refer to the Smooth-Cast ROTOª technical bulletin.
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.

Technical Bulletin