Metal foam is a cellular metal structure with a large volume of gas-filled pores. Metal foam comes in two varieties:
CLOSED-CELL FOAM - with closed pores
CELL-FOAM FILLED WITH SYNTHETIC RESIN - with closed pores
Metal foams have a very high porosity, between 75-95% of the volume is empty and retain many of the characteristics of the metal used to produce them. Metal foams are easily and totally recyclable back into the original metal.