PMC™-780 DRY

Description

This high-performance, two-component urethane rubber cures at room temperature to form a tough, abrasion-resistant elastomer. 

With a Shore A hardness of 80, PMC™-780 DRY offers outstanding strength and durability for demanding industrial and production environments.

• Mix Ratio By Volume: 2A:1B
• Mix Ratio By Weight: 2A:1B
• Working time: 25 minutes
• Cure Time: 48 hours
• Shore Hardness: 80 A
• Specific Gravity: 1.02 g/cc
• Specific Volume: 0.98 cm3/g .
• Color: Light Amber
• Tensile Strength: 62.1 bar
• 100% Modulus: 2758 kPa
• Elongation@Break: 750 %
• Die C Tear Strength: 35.03 kN/m
• Shrinkage <.001 in. / in.
• Mixed Viscosity: 2,000 cps

Instructions

Preparation

• This product has a limited shelf life and should be used as soon as possible.
• Store and use materials at room temperature (23°C) with low humidity.
• Wear safety glasses, long sleeves, and rubber gloves to minimize contamination risk.
• Ensure good ventilation in the workspace.

Some Materials Must Be Sealed

• Models made of porous materials (gypsum plasters, concrete, wood, stone, etc.) must be sealed before applying a release agent.
• Use SuperSeal™ or One Step™ for sealing porous surfaces without affecting detail.
• Sonite™ Wax or high-quality Shellac is suitable for sealing modeling clays containing sulfur or moisture.
• Allow the sealing agent to dry completely before applying a release agent.

Non-Porous Surfaces

• Metal, glass, hard plastics, sulfur-free clays, etc., require only a release agent.

Applying A Release Agent

• Use a mold-making specific release agent like Universal™ Mold Release.
• Apply a liberal coat on all surfaces that will contact the rubber.
• Lightly brush the release agent with a soft brush for thorough coverage.
• Follow with a light mist coating and let dry for 30 minutes.

Because no two applications are quite the same, a small test application is recommended to determine suitability.

IMPORTANT

• Shelf life is drastically reduced after opening. Replace lids immediately after dispensing to prolong shelf life.
• XTEND-IT™ Dry Gas Blanket can significantly prolong the shelf life of unused liquid urethane products.

MEASURING & MIXING

• Liquid urethanes are moisture sensitive. Use clean metal or plastic mixing tools and containers.
• Pre-mix Part B before use.
• Mix Parts A and B thoroughly for at least 3 minutes, scraping sides and bottom of the container.
• For large quantities (11 kg or more), use a mechanical mixer for 3 minutes, followed by hand mixing for 1 minute.
• Pour into a new, clean container and mix again.
• Vacuum degassing can further reduce air bubbles.

Pouring

• Pour the mixture in a single spot at the lowest point of the containment field for best results.
• Ensure the liquid rubber levels off at least 1.3 cm over the highest point of the model surface.

Curing

• Allow the mold to cure for at least 48 hours at room temperature (23°C) before demolding.
• Do not cure rubber in temperatures less than 18°C.
• Cure time can be reduced with mild heat or by adding Smooth-On “Kick-It™” Cure Accelerator.

Post Curing

• After curing at room temperature, heating the rubber to 65°C for 4 to 8 hours will enhance physical properties.

Using The Mold

• Apply a release agent to the mold before each casting.
• Use the appropriate release agent for the material being cast.
• For gypsum plaster, sponge the mold with a soap solution for better flow and easy release.
• In & Out™ II Water Based Release Concentrate is recommended for abrasive materials like concrete.

Performance & Storage

• Fully cured rubber is tough and durable if properly used and stored.
• The physical life of the rubber depends on usage.
• Contact Smooth-On with questions about this material relative to your application.

Specifications