I wanted to try out this 904 Zirconia from Cotronics as a shield from friction and heat on my leading edges of my fins while flying at extreme velocity. The only rocket I have to try it on right now is my L3 rocket, which its top speed is only Mach 2. IMHO, that is where the party starts. I'm thinking on trying this stuff on my N5800 MD rocket. (my next build) That one will be in the Mach 3 range at very low altitude. I want to get a little experience using this stuff, as the numbers on strength are no way close to epoxy. What I ended up doing was thinning out the 904 (thinner came from cotronics made for the 904) to almost water consistency, doesn't take much thinner. Then I coated both sides of a piece of 7/8 inch wide fiberglass tape, got the leading edges wet with 904, and laid the tape over the leading edges of all three fins. Let cure. This stuff doesn't sand very easy, if at all. I believe one weak point of this stuff is its staying put power. If any air gets underneath it at high Mach, it will peel off like a banana. So I put a couple coats of 4461SS Cotronics epoxy over the 904 to help keep it in place. Sanded everything super smooth, and she's ready for some Mach travel. These fins were coated many times with 4461SS before the 904 was applied. If anybody has used this stuff before, I would like to hear your opinion on it. And if not, I'd still like to hear any thoughts on what I've done up until now. Thoughts anyone????????