
Multi layers of material can be added using drop boxes during the oven cycle. An outer skin forms in the mold and a drop box holds the second layer's material that will be released after the outer skin forms.
The primiary purpose of the In mold foam process is to provide maximum structural integrity for large parts that do not need to be completly filled. Addtionally the second layer can provide thermal insulation and added buoyancy.

Second layer foam rotational molded from a in cycle drop box
Post mold foaming is a two part system (AB) process that is injected into the rotational molded part. The Post Mold Foaming method can be either an open or closed cell material.
The primiary purpose of the Post mold foam process is to provide maximum thermal insulation for parts that need to be completly filled. Addtionally the post mold foam can increase structural integrity and buoyancy.

Second layer foam added after rotational molding process
