How sprayed-in-place foam works

The foam ships to us as separate A (isocyanate) and B (polyol) components in 55 gallon drums. Barrel pumps pump the components to a proportioning machine where it is heated and pumped in a 1:1 ratio through heat traced lines under pressure to a spray gun.  

The gun begins mixing the two liquid components the instant the trigger is pulled.  It sprays the mixture onto the surface as a liquid and within 2 to 8 seconds it chemically reacts and rises approximately 30 times its volume.  The few seconds that it is in a liquid state on the surface allows it to self-level and flow down into cracks and fill them with foam.  

Within 2 minutes the foam becomes rigid enough to walk on and is leak tight at that point.  After 2 hours the foam is cured enough to begin applying the acrylic elastomeric base coat.

                                                              AmeriServ, Inc.