3% AFFF Can you make a better aqueous film forming than Denko 6% Concentrate? Not really, but you can make it more cost effective. Doubling the concentration yields a finished foam solution that will cost almost 10% less. This also means doubling the amount of firefighting capability that can be carried to the fire scene and half the amount of space necessary for storage. In addition Denko 3% AFFF is freeze protected and it too has an indefinite shelf-life.