3 lb. Rigid Foam is a 2-part polyurethane expanding foam which expands as much as 18X to create rigid lightweight castings, parts, and backfill reinforcement of other materials. This is a lightweight 3 lb. density rigid foam, which means a cubic foot of expanded foam will weigh 3 lbs.
This product is mostly used as a filler, but works well as a casting medium if used properly. One problem is if you're trying to fill a mold, and you have no way to make it go into all of your detail, it will take the path of least resistance and just foam right out the top. In order to get it to fill that detail, it must be "packed". That is, it must be poured into an enclosed mold so that it builds some back pressure and is forced into all of the detail. In order to do this, the volume of the mold first needs to be estimated. Then, the mold must be capped and an excess amount of foam must be poured into that mold.
In other words, if your mold is one cubic foot in volume, you need to pour enough foam that would normally free rise to approximately 1.1 cubic foot. So, if you are using a 3 lb. density foam, you need to mix 1.6 lbs. of part A plus 1.6 lbs. of part B, which would equal about 1.1 cubic feet of free-risen foam.
This material also makes a great filler for sculpture made out of other materials such as fiberglass, FGR-95, plaster, etc. Just mix and pour, but be careful not to pour too much, as this stuff can develop a lot of pressure and will crack and/or distort your piece if given the chance.
3 lb. rigid foam must be mixed thoroughly in order to work properly. Can be pigmented with Urethane Tints.
3 lb. Rigid Foam can also be used as a dress form foam to create dimensionally accurate body forms which will hold pins for dressmaking. Body sizes will vary, but normally (2) of the 2 quart sets are recommended for a dress form.
- Mix ratio: 1A:1B by volume
- Color: Yellow Beige
- 3 lb. Rigid Foam is available in 2 quart (4.7 lb. net weight) sets, 2 gallon (16.9 lb. net weight) sets, and 10 gallon (86 lb. net weight) sets.
More Prop 65 Info