Procedure for hand mixing rigid polyurethane foam
9900 -2.0 Hand – Mix Polyurethane foam should be mixed 100 to 80 by weight. (Consult specification sheet). Use a scale to measure A and B weight before mixing. (Determine amount required)
To Determine Volume:
Free rise foam weighs approximately 2 pounds per cubic foot. Determine cavity volume and multiply times foam in – place density. (Example: 1.5 cu, ft. X 2.5# Density = 3.75# of foam. Mix 2.1# of “A” with 1.7# of “B” per instructions. Urethane foam requires a pack factor to fill enclosed cavities. 2.5# density was used in the calculation.
TO MAKE FOAM
- Prepare a small can of cleaner for rinsing mixer.
- Pour predetermined weights of A and B chemicals in separate containers.
- 75 – 85 degrees F. is optimum. When ready to mix, pour one chemical into the other and mix with propeller type mixer. Clean mixer mineral spirits or acetone
- Pour mixture into mold or cavity and let expand.
- If molding, demold in 12 to 15 minutes.
IF a molded part is required – apply wax or apply barrier coat to mold. Allow wax or barrier coat to dry. Clamp mold before foaming. Be careful Expanding foam will develop pressure when molding.
- Mixing containers. (16 or 32 oz paper cups)
- Propeller type mixer and drill motor. (Paint mixer is ok)
- Cleaning solvent for mixer.