Alumina foam filters These are typically used for purification of molten aluminum and aluminum alloys. This can be used without fear of failure upto as high as 1200 c. Typical characteristics include: A) Pure white color B) Application temperature < or equal to 1, 200 c C) AL2O3 content: > or equal to 65% D) Typically used in molten aluminum and alloy filtering E) Pore size: 10 - 50 ppi.