the reson behide the copper spray is it helps dissipate heat to provent gaskit blow out so it help prevent your gaskit from getting hot and burning up

 

I thought it just formed a better seal. Liquid flows into cracks better than solid matter. Makes since to me.

 

used it last time i did a head gasket, started the car, checked for leaks, etc...and went to the track. on the way back got into a top speed run with a Cav z24 and ran it till she shut off. NO problems whatsoever. don't know if the copper spray helped the seal any, but it shonuff didn't hurt.