When using spray urethane foam, proper temperature is very important; this means the air temperature, and the temperature of the chemicals and the surface to which they are being applied as well. Optimal operating temperature of the chemicals is around 70 - 80 degrees Fahrenheit. The surface one intends on applying the foam to should be at least 65 degrees.
When temperatures aren't right, foam will not cure properly. Insufficient chemical temperature will cause the foam to remain tacky; if the chemicals are cold enough, it may not cure at all. This condition greatly reduces the effectiveness of the foam. If the surface to which the foam is being applied is too cold, the foam may peel away from the surface, leaving air gaps & reducing R-Value. Applying too much thickness at once may yield the same result.
This article, courtesy of The Snell Group, gives a brief explanation of how Infrared Thermography can be used to diagnose a spray foam failure: Click Here
Thank you & Stay Warm!
Jesse M.