I had a guy way back on another site state that he could not get his Cometics' to seal until he sprayed all 3 layers with Permatex "high tack" part # 99MA the red stuff in a spray can . I've used it on paper/fiber and composition gaskets with excellent results as it is extremely tacky, goes on light & seals very well. I've used Permatex copper coat spray on steel head gaskets but I did not like the way it went on (too thin/runny). I'm wondering if aluminum (silver?) spray paint would do better (on steel shim gaskets) which has been recommended but I have yet to try it.