VFI-3161 60 A MDI Molding Rubber

Thickness Requirements

Pour the material in one spot at the lowest point of the mold until the desired thickness is reached. VFI recommends pouring at least ½ of an inch thick.

Mold Preparation

The molding surface must be clean, dry, and free of dirt, oils, and debris. Use only non-sulfurous clay on molds to prevent unwanted adhesion and improper cure. The molding surface must be fully sealed and non-porous. Use a release agent to prevent adhesion. We recommend using Chem-Trend MR-515 Aerosol or a similar release agent. Spray several layers over the entire mold, waiting for the surface to dry before adding more. The release will help protect and extend the life of the mold. Spraying too much release can produce a shiny/glossy surface on the rubber that will transfer over to future castings. The material is compatible with most molds as long as it is used with a proper release agent.

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 2 parts of the “B” component by volume, 100 parts “A” component to 182.15 parts “B” component by weight.  Thoroughly mix for at least 30 seconds while ensuring the mix is uniform and homogenous. Transfer into a new, clean container and mix again before use. Be sure to scrape the sides and bottom of the container for uniformity.

Post-Cure

Allow the rubber to sit at room temperature for a minimum of 16 hours before demolding. It will develop full physical properties after 7 days at room temperature. It is required that the rubber sits for 3 days at room temperature before use or shipping. When using the rubber for casting, apply a release agent before each use. Use a release agent from a reputable release company, such as Chem-Trend, Stoner Molding Solutions, or Cresset Chemical Co. Do not use a solvent-containing release, as it can distort (shrink or expand) the mold.

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. VFI-3161 must be protected from freezing as it is difficult to unfreeze the material. Once open, use it immediately. If you plan to store open containers after use, both sides must be nitrogen purged.

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. Urethane is moisture-sensitive and may foam when exposed to too much moisture, so use VFI-3161 in a controlled, high-production environment to limit moisture interaction. Use only with adequate ventilation. Do not thin or add foreign material to the product. It must be protected from freezing. See the Safety Data Sheet for complete safety instructions.