Smooth-On offers a variety of foam materials including our Foam-iT!® series rigid polyurethane foams, FlexFoam-iT!® series flexible polyurethane foams, and Soma Foama® series platinum-based silicone foams.
Each Smooth-On foam has a number associated with it that represents the free-rise density or cubic foot "yield-per-pound" of the foam. Larger numbered foams have a higher density, whereas lower numbered foams have higher expansion rates.
For example, if you poured Foam-iT! 5 liquid into a cube measuring one cubic foot and the foam expanded to 12"x12"x12", it would weigh 5 lbs. If you pour Foam-iT! 10 liquid into the same cube, it would fill the same space and again expand to 12"x12"x12" (1 cubic foot). However, the Foam-iT! 10 cube would weigh 10 lbs. due to a higher density.
The raw materials used to make them. Smooth-On never uses "off spec" or "waste stream" polyols that are often used to formulate foams for making products like furniture, shoes and other commodities. Smooth-On also uses filtered water in the production of its foams. As a result, Smooth-On foams have higher physical and performance properties than waste stream foams. With several densities to choose from, Smooth-On foams are premium formulations that are consistent from batch to batch ensuring the user a more predictable outcome every time.
Foam-iT! and FlexFoam-iT! castable foams are water-blown polyurethane foams that expand and cure quickly to solid, strong, lightweight foams. These types of foams are also known as "cold foam" because they do not require baking in an oven to cure. They are designed to be processed and cure at room temperature (73°F / 23°C).
Foam-iT! foams are closed cell. Closed cell foams provide a better surface finish, especially when backpressure is applied during casting. Closed cell foams also provide better water resistance.
All of the FlexFoam-iT! foams are flexible, but some are more pliable than others. FlexFoam-iT! III, V, VI, VIII and X are very pliable or supersoft foams. On the other hand, FlexFoam-iT! IV, 17 and 25, although still bendable, exhibit a more tight foam cell structure and are less "squishy" compared to the supersoft foam versions.
Yes, Smooth-On's Foam-iT! and FlexFoam-iT! series are both iso foam formulations, making them very high quality while being easy to use. These foams are also commonly referred to as "AB foams" in reference to their two-component (Part A & Part B) nature.
Drill mixing (using a drill with mechanical mixer attachment, such as a "turbine" mixer) will introduce more air into the system, causing the foam to expand more. Below is an image showing the difference between drill mixing and hand mixing.
To Paint Foam-iT! Rigid Foam: You can prime and paint the cured surface of rigid foams in the same way that you would cured resin. First prime the casting using 1-2 coats of a high quality auto body primer followed by acrylic enamel paints.
To Paint FlexFoam-iT! Flexible Foam: If you attempt to paint a flexible foam with a standard latex or acrylic paint, the painted surface could crack when the flexible foam part is flexed. You need a paint that will bend and flex with the flexible foam. Many use Smooth-On's Brush-On 40 urethane rubber thinned with a small amount of mineral spirits as a paint. It is easily color pigmented with SO-Strong color tints. You can also paint the cured surface of flexible foam with fabric paint or flexible acrylic enamel paints. You must make sure the paint adheres to the foam and is flexible after it dries.
You can obtain a better surface finish when casting foam by utilizing back pressure. Read our guide on improving the surface finish of foam.