High Lift or single-pass foams that can be sprayed in 2+ inches in one-lift, are becoming increasingly popular and offer increased yield, reduced spray time, and pose less of a fire hazard. However, if not understanding the limitations of this product, failure can occur when used in applications where not appropriate. This is especially true in cold-climates, cold storage, and indoor ice-skating rinks applications.
High-lift Closed-Cell Spray Foam sprayed in warm weather in 3+ inch passes can heat up excessively; during the curing period the cell structures can expand beyond what is intended. The cells should be round and tight, filled with the blowing agent 245fa, Soltice or the like, to create the necessary R-value. With excessive heat the blowing agent gas will expand and deform the cell walls; instead of being nice, round, and tight, they may end up elongated and oval in shape. This can affect the dimensional stability of the cell walls (an oval shape is not as strong as a circle). At the first presence of cold weather, the blowing agent inside the cells shrinks, thereby placing inward pressure on the outside walls and causing them to collapse. This process is what we call “thermal shock”, and can lead to shrinking and cracking foam.
Believe me, after spraying millions of pounds of closed-cell foam over the last 20 years, I've made my mistakes early on and have seen my fair share of cracking, popping and shrinking closed-cell foam. These mistakes can often result in very costly call-backs. So proceed with the utmost caution and diligence.
We strongly advise that when spraying high-lift closed-cell foams in northern climates during the warm months or in cold storage facilities, that no more than 3” at a time be installed in a single-pass; then wait until the core temperature is 100 degrees or below before applying the second layer. And remember to make sure the lines are completely flushed of open-cell before switching to closed-cell foam! This should ensure there will be no thermal shock and costly call-backs!
Back at my old application company our single largest source of call backs was related to shrinking and cracking closed-cell foam. These problems even occurred when spraying only 2" of closed-cell foam. After switching to Gaco Western One-Pass high-lift closed-cell foam, we allowed our sprayers to spray 3" in a single pass and all thermal shock related call backs became non-existent.
For more information you can email Juan directly at Juan@AllFoamTech.com