There are other methods to determine the ash content, but this method is the most economical and applies to 90% of the samples tested at ARDL. A sample is placed in a porcelain boat, weighed, and ashed in a muffle furnace at 550° C for two hours. The weight percent of total filler is then calculated gravimetrically. If the polymer is Silicone Rubber and the formulation contains some additional materials such as flame retardants and certain other chemicals, excessive ash can be generated upon pyrolysis in the furnace.

If this is the case, the calculated density of the reconstructed formulation is used as a criteria to adjust the levels of ash generated by these materials.

Fillers are typically non-reinforcing, inorganic additives such as clays, chalk, metal oxides, silicas and silicates added to modify and improve on certain physical or physical-chemical properties such as resistance to abrasion, permeation, swell, tear, or perhaps even modifying product cost without reducing the required performance.