Smooth-Cast™ 300

cast300xx ⓘ 73F46CFE-B3F3-DA4F-A387-270D6DC72480
Polyurethane Resin

Ultra-low-viscosity casting resin that yields bright white, virtually bubble-free castings with an easy 1:1 mixing ratio. Fast curing with short pot-life.

  • Mix ratio: 1:1 by volume
  • Working time: 3 min
  • Cure time: 10 min
  • Shore hardness: 70D
  • Resistant to moisture and mild solvents
exclamation.svg health-hazard.svg

Danger

H315 - Causes skin irritation.
H317 - May cause an allergic skin reaction.
H320 -
H332 - Harmful if inhaled.
H334 - May cause allergy or asthma symptoms or breathing difficulties if inhaled.
€ 667.50

(€ 551.65 without 21% VAT)

In stock

Description

Smooth-Cast™ 300 is an ultra-low viscosity casting resin that cures to a bright white finish with minimal bubbles, eliminating the need for vacuum degassing. 

It is easy to mix at a 1A:1B ratio by volume or a 100A:90B ratio by weight.

This resin accepts fillers like URE-FIL™ 3 and can be tinted with SO-Strong™ or Ignite™ colorants. Once fully cured, the castings are tough, durable, machinable, and paintable, with resistance to moisture and mild solvents.

Applications include reproducing small to medium sculptures, creating prototype models, special effect props, and decorative jewelry. 

For roto cast projects, refer to the technical bulletin of a related product.

Features

  • Easy to measure and mix with a 1:1 ratio by volume
  • Low viscosity captures excellent detail without degassing
  • Resin cures to a bright white finish
  • Pot Life: 3 minutes
  • Cure Time: 10 minutes
  • Elongation at Break: 5%
  • Shore Hardness: 70D

Instructions

  • Mix the resin at a 1A:1B ratio by volume (or 100A:90B by weight). 
  • Stir thoroughly and pour into the mold. 
  • With a 3-minute pot life, work quickly. 
  • Demold in about 10 minutes. 
  • The low viscosity reduces bubbles and captures fine detail without degassing. 
  • Cured parts are white, rigid (Shore 70D), durable, and machinable. 
  • Can be tinted or filled. 
  • Suitable for prototypes, props, and small castings.

Safety:

  • Store and use materials in a warm environment (23°C).
  • Use products promptly due to limited shelf life.
  • All liquid urethanes are moisture-sensitive; use clean metal, glass, or plastic tools and containers.
  • Work in a well-ventilated area and wear safety glasses, long sleeves, and rubber gloves.
  • Conduct a small test application to ensure material suitability for your project.

Applying a Release Agent:

  • Use a mold-specific release agent like Universal™ Mold Release or Mann’s Ease Release™ 200.
  • Apply liberally to all surfaces contacting the plastic.
  • Brush with a soft brush for thorough coverage, then mist and let dry for 30 minutes.
  • Smooth-On silicone molds may not need a release agent unless casting silicone.

Measuring & Mixing:

  • Ensure tools and containers are clean and dry.
  • Stir or shake Parts A and B thoroughly before dispensing.
  • Mix equal amounts by volume or 100A:90B by weight, scraping sides and bottom of the container.

Pouring, Curing & Performance:

  • Pour mixture at the lowest point to minimize air entrapment.
  • For best results, use pressure casting at 0.42 MPa (60 PSI) during curing.
  • Ensure adequate ventilation to dissipate fumes during curing.
  • Allow castings to cool to room temperature before handling.
  • Post-cure at 65°C for 4-6 hours to enhance properties.
  • Cured castings are rigid, durable, and resistant to moisture and mild solvents.
  • Unpainted castings may yellow over time with UV exposure.

Specifications

Color White
Mixed Viscocity 80 cps
Cure Time 10 minutes
Pot Life 3 minutes
Flexural Strength 4,510 psi
Flexural Modulus 128,000 psi
Specific Volume 26.4 cu. in./lb.
Specific Gravity 1.05 g/cc
Mix Ratio By Weight 100A:90B
Shrinkage 0.01 in. / in.
Mix Ratio By Volume 1A:1B
Tensile Strength 3,000 psi
Elongation At Break 5 %
Shore D Hardness 70
Heat Deflection Temp 120 °F
Compressive Strength 4,000 psi
Tensile Modulus 139,500 psi
Compressive Modulus 45,800 psi
Available in Polyurethane Resin
Product Cure Time Specific Gravity Specific Volume Tensile Strength Tensile Modulus Compressive Strength Compressive Modulus Flexural Strength Shrinkage Heat Deflection Temp Elongation At Break Flexural Modulus Mixed Viscocity Mix Ratio By Volume Mix Ratio By Weight Pot Life Shore D Hardness Color Mixed Viscocity Cure Time Pot Life Flexural Strength Flexural Modulus Specific Volume Specific Gravity Mix Ratio By Weight Shrinkage Mix Ratio By Volume Tensile Strength Elongation At Break Shore D Hardness Heat Deflection Temp Compressive Strength Tensile Modulus Compressive Modulus
Smooth-Cast™ 300Q 5 min. 1.05 g/cc 26.4 cu. in./lb. 3,000 psi 139,500 psi 4,000 psi 45,800 psi 4,510 psi 0.01 in. / in. 120 °F 5 % 128,000 psi 80 cps 1A:1B 100A:90B 30 sec. 70 White 80 cps 5 min. 30 sec. 4,510 psi 128,000 psi 26.4 cu. in./lb. 1.05 g/cc 100A:90B 0.01 in. / in. 1A:1B 3,000 psi 5 % 70 120 °F 4,000 psi 139,500 psi 45,800 psi
Smooth-Cast™ 300 10 min. 1.05 g/cc 26.4 cu. in./lb. 3,000 psi 139,500 psi 4,000 psi 45,800 psi 4,510 psi 0.01 in. / in. 120 °F 5 % 128,000 psi 80 cps 1A:1B 100A:90B 3 min. 70 White 80 cps 10 min. 3 min. 4,510 psi 128,000 psi 26.4 cu. in./lb. 1.05 g/cc 100A:90B 0.01 in. / in. 1A:1B 3,000 psi 5 % 70 120 °F 4,000 psi 139,500 psi 45,800 psi
Smooth-Cast™ 305 30 min. 1.05 g/cc 26.4 cu. in./lb. 3,000 psi 134,000 psi 3,800 psi 44,900 psi 4,000 psi 0.0065 in. / in. 120 °F 7.5 % 118,000 psi 80 cps 1A:1B 100A:90B 7 min. 70 White 80 cps 30 min. 7 min. 4,000 psi 118,000 psi 26.4 cu. in./lb. 1.05 g/cc 100A:90B 0.0065 in. / in. 1A:1B 3,000 psi 7.5 % 70 120 °F 3,800 psi 134,000 psi 44,900 psi
Smooth-Cast™ 310 4 h. 1.05 g/cc 26.4 cu. in./lb. 3,000 psi 134,000 psi 3,800 psi 44,900 psi 4,000 psi 0.0065 in. / in. 120 °F 7.5 % 118,000 psi 80 cps 1A:1B 100A:90B 20 min. 70 White 80 cps 4 h. 20 min. 4,000 psi 118,000 psi 26.4 cu. in./lb. 1.05 g/cc 100A:90B 0.0065 in. / in. 1A:1B 3,000 psi 7.5 % 70 120 °F 3,800 psi 134,000 psi 44,900 psi
Smooth-Cast™ 385 2 h. 1.60 g/cc 17.3 cu. in./lb. 3,100 psi 400,000 psi 8,500 psi 400,000 psi 5,900 psi 0.0006 in. / in. 135 °F 1 % 433,000 psi 3,000 cps - 1A:5B 20 min. 85 Beige 3,000 cps 2 h. 20 min. 5,900 psi 433,000 psi 17.3 cu. in./lb. 1.60 g/cc 1A:5B 0.0006 in. / in. - 3,100 psi 1 % 85 135 °F 8,500 psi 400,000 psi 400,000 psi

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