PMC™-790

Description

This two-component urethane rubber cures at room temperature to form a tough, durable elastomer with a Shore A hardness of 90. It is the hardest and most rigid in its series, designed for demanding industrial applications requiring superior strength, abrasion resistance, and dimensional stability.

The formulation provides excellent tear and chemical resistance, making it suitable for concrete form liners, casting molds, rollers, industrial pads, and tooling applications that must endure heavy wear and stress. 

PMC™-790 offers low shrinkage, ensuring precise detail reproduction and long mold life, even under repeated casting conditions.

Its low viscosity allows for easy mixing and pouring, capturing intricate surface detail without air entrapment. Once cured, the rubber maintains its mechanical properties under compression or load. It can be pigmented with specific colorants for identification or design flexibility.

This product is the professional choice for high-duty molds and industrial rubber components, providing maximum hardness, stability, and long-term performance in challenging environments.

Instructions

Preparation

• Store and use at room temperature (23°C).
• Material has a limited shelf life and should be used promptly.
• Wear safety glasses, long sleeves, and rubber gloves to minimize contamination risk.
• Ensure good ventilation.

• Models made of porous materials (gypsum plasters, concrete, wood, stone, etc.) must be sealed before applying a release agent.
• Use Sonite Wax™ for sealing porous surfaces. Apply two thin layers of wax and let dry.
• For modeling clays with sulfur or moisture, use high-quality Shellac.
• Thermoplastics (polystyrene) must also be sealed with shellac or PVA.
• Allow sealing agent to dry completely before applying a release agent.

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

• A release agent is necessary to facilitate demolding when casting into or over most surfaces.
• Use a release agent made specifically for mold making (e.g., Universal™ Mold Release).
• Apply a liberal coat of release agent onto all surfaces that will contact the rubber.
• Lightly brush the release agent with a soft brush over all surfaces of the model.
• Follow with a light mist coating and let the release agent dry for 30 minutes.

• Liquid urethanes are moisture sensitive and will absorb atmospheric moisture.
• Mixing tools and containers should be clean and made of metal, glass, or plastic.
• Store and use materials in a warm environment (23°C).
• Pre-mix Part B before using.
• Mix Parts A and B thoroughly for at least 3 minutes, scraping the sides and bottom of the mixing container.
• If mixing large quantities (10.88 kg or more), use a mechanical mixer for 3 minutes followed by careful hand mixing for one minute.
• Pour the entire quantity into a new, clean mixing container and mix again.
• For bubble-free castings, consider vacuum degassing or pressure casting.

• Pour the mixture in a single spot at the lowest point of the containment field.
• Let the rubber seek its level up and over the model.
• The liquid rubber should level off at least 1.3 cm over the highest point of the model surface.

• Allow rubber to cure for at least 48 hours at room temperature (23°C) before demolding.
• Do not cure rubber where temperature is less than 18°C.

• After curing at room temperature, heat the rubber to 65°C for 4 to 8 hours to increase physical properties and performance.

• Apply a release agent to the mold before each casting.
• The type of release agent depends on the material being cast.
• For wax, liquid rubber, or thermosetting materials, use a spray release made specifically for mold making.
• For gypsum plaster materials, sponge the mold with a soap solution for better plaster flow and easy release.
• In & Out™ II Water Based Release Concentrate is recommended for releasing abrasive materials like concrete.

• Fully cured rubber is tough, durable, and will perform if properly used and stored.
• The physical life of the rubber depends on how you use it.
• Contact the manufacturer directly with questions about this material relative to your application.

Specifications