Insulation capability of refractory materials is frequently compared using the Coefficient of Thermal Conductivity, or "K Factor".  This property is also used to calculate expected heat loss and shell temperatures of refractory lined vessels.  The K Factor for low cement and for acid bonded monoliths in the range of 70% alumina is around 15 BTU/Hr-Sq Ft-In.  These types of products are commonly used in metal contact areas because of their strength and relative stability at molten aluminum temperatures.  WAM® AL II  is a micro-porous metal contact refractory with a K Factor of 4.7 BTU/Hr-Sq Ft-In at about 1500 °F, roughly three times the insulating capability of other metal contact refractories.

Corundum is aluminum oxide, and when it gets out of control, it reduces furnace efficiency and uses up valuable maintenance efforts.  Wherever oxygen comes in contact with aluminum, corundum will form, but by limiting available oxygen sources, including reducible components of refractory linings, corundum growth can be minimized.  While commonly used refractory linings have about 30% silicon dioxide, (an easily reducible component of the lining), WAM® AL II contains less than 0.3% silicon dioxide, virtually eliminating the possiblity of corundum formation within the refractory lining.  And even though other sources of oxygen may allow corundum growth, WAM® AL II can be easily cleaned since corundum can't penetrate the surface.