Night hicker:

You are right, the "foam used is AFFF or aqueous film forming foam) Its like a bubble bath for an aircraft, and like a bubble bath if you don't like the bubble on you whip it off. It has two(2) actions smother and cool. It is despernced by a special truck that mixes the raw foam with water. I am sorry i don't remember the percentages of foam to water, but it may be adjusted at the truck to make the foam thicker or thiner. The thick stuff is used on the runway when a aircraft is landing wheels up. This reduces the sparks and hopefully the fire danger. After we are thru with the foam it is washed away with clear water, lots of water.