Make sure there are no gashes to the HG, meaning no little pieces that scratch your fingers as you run over it. Make sure it is CLEAN, between ALL layers. I used carb cleaner to break down all the oil, then used a water/detergent base to get the rest of it. Flushed in between the layers with high pressure water, then dried it by hand. I used a green scrub pad to get off all of the material stuck to it. I laid it on a CLEAN, dust free work bench, and went to town.
I did all this work, and while I was bored one day I went to look at it closer because my gut had this weird feeling. That's when I saw the small cracks.
I have used copper sprays and such, but I doubt they do anything. They just make more sticky stuff you'll have to clean off if you change it again. At the pressures of a power stroke, anything soft enough to come out of a spray can isn't going to do jack. I sprayed three coatings on it, let it cure/dry. I then took my fingernail, and cut right through it so easily. You are only relying on the seal that the MHG in between the head/block generate.
I also recommend tightening several ft./.lbs more than the HG had on it before. You really want to get it to bite again. I was at 85 the first time, then went to 93 the second time on it.
I went cometic on my new motor, no sealing products needed or intended by the manufacturer, a dry install. Perfect results.
.
