While the above methods typically produce microbubbles containing
monocellular cores, those containing multicellular gas cores can also be
used as the filler. An example of multicellular spheres is the polystyrene
foam "prepuff" used in the manufacture of insulated cups, food trays, and
pre-formed packing materials. Such spheres are generally produced in a
size range exceeding that which is preferred. More importantly, bright
coloration of such spheres is difficult because the puffing process
renders the spheres more pastel in value.