Chemical foams began in the late 1800’s and continued to around WW II.
Two dry chemicals (powders) were mixed with water, in either fire extinguishers or in hoppers (called generators). The reaction would create CO2 which acted as the air and would cause agitation and develop and expel a bubble foam.
One chemical was an acid base. The other an alkaline. One was usually labeled A, the other B.
The hopper was split – so the chemicals did not mix until the water was added.
Chemical foam did not perform well (bubble up) in cold weather.
The chemicals and fire extinguishers were often labeled under their common trade name “Foamite”.
Photos courtesy of the Rolling Thru Time Auto Museum, Tucson, AZ
