What to do if polyurethane foam becomes brittle and hollow after curing

what to do if polyurethane foam becomes brittle and hollow after curing foam caulking agentcommonly known as foam glue,is a polyurethanethat relies on moisture to cureelastic sealing foam material. in the usual construction of foam caulking agents, i don’t know if you have encountered this phenomenon. after the foam glue is cured, there will be…