Rookie Mistake

[Richard Flanders]

I don't know about the rest of you guys but when Edgar opines on metallurgy, I listen carefully and believe what he says. I'd love to put a wire into each of his ears and "download" his knowledge base on the subject. I never use Simple Green in my sonic cleaner. The ammonia in it is obnoxious and can not be good for any metal. I can't even stand to use that stuff on the sink with a sponge. The fumes play hell with my sinuses. I've permanently shelved what I have in stock in favor of pine oil cleaners.

I made a similar screwup recently with another cleaner and a gun part. I machined out an 80% AR lower of 7075 T6 aluminum. I always soak them in hot water with Dawn dish soap to get the oil off but added some Oxi-clean to this last soak, which was a mistake. Oxi-clean is a peroxide compound thus an oxidizer. 7075 is alloyed with something (Zn?-can't remember right now) and the O-clean darkened the entire lower slightly and caused some black spots where there were larger accumulations of the alloyed metal, which is clearly more subject to oxidation than the aluminum. No real damage to the lower but it's clearly microscopically etched. Won't make that mistake on the next one I can tell you. All in all this spring thing is a good lesson to us all on using sonic cleaners to clean gun parts.