The most common polymer used is polyurethane. Foaming the polymer creates small open cells that can hold fluids. Cell size can be controlled during the foaming process. Foam products can also possess additional features such as film backings, adhesive coatings, island configurations, and different thicknesses. Combinations of foam thickness, film backings, and adhesive coatings are what leads to the diversity of foam dressings.
Foams are available in traditional thickness versions and in extra thin versions.
Foams may have a waterproof film covering on their top surface. Often this film covering is the same material as a transparent film dressing. The foams may also have an adhesive coating over the wound contact side or as a border on their perimeter. Foams also are available in island configurations. At least one brand of foam contains a surfactant within the foam to aid in its fluid handling properties.