Re: [VAC] Expanding foam sealant

["Dr. Gerald N. Johnson" <geraldj@ames.net>]

Some processed foams have the thin walls of the gas bubbles removed
chemically to make the foam totally porous. Foam foamed in place usually
has closed internal bubbles so while its filled with gas, its not open.
If the internal bubbles join before it solidifies, the whole structure
of the foam converts to one bubble and the whole concept of foam
disappears.

Gerald J.