VFI®-4840 40 A TDI Casting Elastomer

Thickness Requirements

Cast the liquid elastomer into a single spot at the lowest point of the mold until it is filled. If you are casting thin parts, we recommend using an elastomer with a higher Shore A hardness.

Mold Preparation

The mold should be clean and free of oils, dirt, or debris before casting. The elastomer is compatible with most molds as long as the mold is sprayed with a proper release agent to prevent adhesion. We recommend using Chem-Trend MR-515 Aerosol or a similar release agent. Using a release agent helps to protect and extend the life of the mold and allows the part to release easily. Avoid spraying too much release on the mold, as this can produce a shiny/glossy surface on the cured elastomer.

Mixing

The material should be at least 65°F before use for proper mixing and application. Mixing times may vary depending on volume and mixing method. Vacuum degassing can further reduce air entrapment but is not required.

Thoroughly mix the POLY “B” component before mixing with the ISO “A” component. Usually, this takes a minimum of 3 minutes per “B” container with proper mixing equipment. Once the “B” component is thoroughly mixed, properly pour 1 part of the “A” component into 1 part of the “B” component by volume, 100 parts “A” component to 97.3 parts “B” component by weight. Thoroughly mix for at least 30 seconds while scraping the sides and bottom of the container, ensuring the mix is uniform and homogeneous. Transfer to a separate, clean mixing container and mix again before use.

Post-Cure

Allow the cast part to sit in the mold at room temperature for a minimum of 16 hours before demolding. The elastomer will develop full physical properties after 7 days at room temperature. It is required that the part sit for 3 days at room temperature before use or shipping.

Storage/Shelf Life

Store between 60°F – 90°F in a clean, dry building. The shelf life of unopened containers is 12 months after the date of manufacture. Once open, use it immediately. If you plan to store open containers after use, both sides must be nitrogen purged to try to extend the material’s shelf life.

Precautions

This product contains isocyanate, which can irritate the skin and is toxic if inhaled as particulate matter. Avoid prolonged breathing of vapors and repeated skin contact. It is not UV color stable and has no long-term UV testing. Urethanes are moisture sensitive and may bubble if exposed to too much moisture. Use only with adequate ventilation. Do not thin or add foreign material to the product. See the Safety Data Sheet for complete safety instructions.