Foam FAQs

What is density?

Density is measured in pounds. The more dense a foam is, the higher the quality and the longer it lasts. Choose density depending on how often you use the item and how long it needs to last. Our open-cell foams come in the following grades:


What is firmness?

Firmness is how easily foam compresses and is indicated by an IFD (indentation force deflection) value. The higher the value, the firmer the foam. We recommend you give foam samples the sit or lie test by visiting one of our shops. You can find like firmnesses across the different densities, or grades, of foam. Our open-cell foams generally come in medium-firm and firm, and some soft.

How is foam made?

Flexible polyurethane foam is made by mixing two key raw materials, a polyol and a diisocyanate, with a primary blowing agent—water or CO2—which produces an exothermic (heat-generating) reaction. The mixture is poured onto a moving conveyor in a chamber with sides that are 3 to 4 feet high. As the mixture reacts, bubbles form and the mixture expands—like bread rising. When the reaction completes, the resulting slab of foam is cut and stored for curing.

Making latex foam rubber begins with removing latex, or sap, from the trunk of a rubber tree (Hevea brasiliensis). Using the Dunlop method, the latex is mixed with water, and the resulting suspension is whipped to a froth, then poured into a mold and vulcanized. During the heating process, molecular crosslinks form, which is what allows the foam to recover its shape after being compressed. After the foam cools, it is washed and dried.

What’s the difference between open-cell and closed-cell foams?

The cells in open-cell foams are “broken,” or connected to each other, which allows air to fill the open spaces, making the foam relatively soft. Closed-cell foams have cells that are unbroken, which means air or water cannot easily be absorbed.

Does foam off-gas?

Foam is an inert substance once it has been cured. Foam in its cured state does not produce toxic off-gassing, carcinogens, or volatile organic compounds.