Smooth-Cast™ 305

cast305pint ⓘ B0D491AF-31C2-CC4C-93C4-96C3DE6F0591
Polyurethane Resin

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

  • Shore hardness: 65 D
  • Working time: 7 minutes
  • Demold time: 30 minutes
  • Mix ratio: 1A:1B by volume
  • Low viscosity for easy mixing and pouring
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.
€ 26.44

(€ 21.85 without 21% VAT)

In stock

Description

This fast-curing, low-viscosity casting resin is ideal for creating detailed parts and prototypes.

Smooth-Cast™ 305 features a simple 1A:1B mix ratio by volume, making it easy to use for beginners and professionals alike.


The Smooth-Cast™ 300 Series of liquid plastics are ultra-low viscosity casting resins that yield castings that are bright white and virtually bubble free. Vacuum degassing is not necessary. They offer the convenience of a 1A:1B by volume or 100A:90B by weight mix ratio. 

The differences between them are pot life and demold time.

Features

  • Shore  hardness: D 65
  • Working time: 7 minutes
  • Demold time: 30 minutes
  • Mix ratio: 1A:1B by volume
  • Low viscosity for easy mixing and pouring

The resin cures quickly, allowing for rapid production of castings. It captures fine details and is suitable for prototyping and model making.

Instructions

  • Mix resin at a 1A:1B ratio by volume. 
  • Stir thoroughly, ensuring to scrape the sides and bottom of the container. 
  • Pour the mixture promptly into the mold; the pot life is 7 minutes. 
  • The low viscosity helps capture fine detail. 
  • Demold the casting after approximately 30 minutes. 
  • Once cured, the parts reach a Shore 65D hardness, making them ideal for prototypes and detailed 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 30 minutes
Pot Life 7 minutes
Flexural Strength 4,000 psi
Flexural Modulus 118,000 psi
Specific Volume 26.4 cu. in./lb.
Specific Gravity 1.05 g/cc
Mix Ratio By Weight 100A:90B
Shrinkage 0.0065 in. / in.
Mix Ratio By Volume 1A:1B
Tensile Strength 3,000 psi
Elongation At Break 7.5 %
Shore D Hardness 70
Heat Deflection Temp 120 °F
Compressive Strength 3,800 psi
Tensile Modulus 134,000 psi
Compressive Modulus 44,900 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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