VFI®-4620 65 A Polyurethane Casting Elastomer

Thickness Requirements 

There is no limit to thickness when using VFI-4620, but if you are pouring or injecting less than 1/16th of an inch thick, you will have to post-cure the material. When casting by hand, pour the material into a single spot at the lowest point of the mold.

Mold Preparation 

All surfaces must be clean and free of dirt, debris, and oils that could contaminate the material. For proper demolding, the surface must be sealed with a release agent. A release agent will help extend the life of the mold and prevent unwanted adhesion. Compatible molds for casting include urethane and metal when properly prepared. The material can be used with platinum silicone molds but will create a surface tack, so it must be post-cured after demolding. Our recommended mold temperature is at least 70°F to achieve the specified demold time and properties.

Mixing 

Premix the B side (Poly) until uniform before combining with the A side (Iso). We recommend injecting this material due to the short working time, but it can also be hand-poured. When pouring by hand, pour 1 part B component into 1 part A component by volume, 1.00 parts B component to 1.04 parts A component by weight. Mix the material until uniform, making sure to scrape the sides and bottom of the container. You may mix smaller amounts by hand, but we recommend using a power mixer if you are using over ½ a gallon of material. Smaller amounts can be transferred into a new container and mixed again until uniform. The material must be fully mixed and used before the duration of the pot life, which will shorten at temperatures above 72°F.

Post-Cure

Allow the material to cure for at least 30 minutes at room temperature (77°F) before demolding. Thinner pours will need more time to cure to develop the necessary green strength to demold. It will reach full physical properties after 7 days at room temperature. To achieve final properties faster, the material can be post-cured in an oven at 150°F for 16 hours. When using a silicone mold, the material must be post-cured at room temperature for one day or at 150°F in an oven for 2 hours to remove surface tack.

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 immediately, but if storing after opening, both sides must be nitrogen purged.

Precautions 

VFI-4620 contains isocyanate, which is irritating to the skin and toxic if inhaled. Avoid prolonged breathing of vapors or repeated skin contact. Use only with adequate ventilation. The material is not UV color stable and has no long-term UV testing. It is sensitive to moisture and cannot be cross mixed with other materials. Do not thin or add foreign material to the product. See the Safety Data Sheet for complete safety instructions.