Originally Posted by tre9er

Some other members have chimed-in that it's difficult to get the foam to actually expand from just a few entry points drilled in the lid. I'm thinking cutting the top layer off of the lid, filling with foam, then replacing/caulking the lid back together is a possibility...but I use blankets and last brew might have lost 1.5* over 65 minutes.

Originally Posted by TimpanogosSlim

Also worth stating that the cooler lids are often just hollow plastic. Some people use expanding urethane foam ("great stuff" - cracks and gaps version) to insulate them.

I keep meaning to try that, but haven't gotten around to it yet.