Integral skin foam, or self skinned foam, is a natural surface occurrence of our injection molded foam process. This skin of integral skin foam not only increases the attractiveness of the part but adds durability as well.
The integral skin foam phenomenon occurs when the resin interfaces with the high temperature aluminum of the mold. This high temperature "cooks" the resin so completely that the foam cell size is reduced to microns, creating an extremely dense version of the foam on the outside surface of the part. As you can see in the enlarged microscope photograph below, the outside of the foam has solid looking area (skin) with seemingly no cell structure. The foam cells that reside on the inside of the skin are heavily protected by the thicker integral skin area, creating a durable protective layer.
The strong integral self skinned foam surface provides protection against scratch, wear-n-tear and abrasion, which improves durability in a rough physical environment. Under normal conditions it will take many hundreds of hours of constant abrasion to remove the skin and expose the inside cell structure.
Products that require long lasting usability can benefit from the tough integral skin foam that is created with this process. Whether it is an outdoor product like a backpack or a kayak rack or something you would use indoors like a foam toilet seat, the long life of integral skin foam products makes for happy customers.
If you have any doubt, think of how many miles have been walked in Crocs sandals.