a while ago, like, probably last august, i made an EX motor out of a copper pipe and pourstone for the nozzle. this was a sugar based motor. i had never used a copper pipe before for the casing, but i did this time. well, i went outside today to grab a tool, and there's that copper pipe laying there. only, i didnt notice that it was a copper pipe at first, i actually looked like stained glass. i was completely glazed in a bright aqua blue color. now, i knew that copper when burned creates blue effects, but i didnt know that just by heating it it will have that effect over time....it looks like corrosion, im wondering if its oxidation, like rust. also, i thought that copper turns green when it oxidizes, so was this purely from the heat created?