Hey, I am sure that this question has been asked before, but here it goes. I have 2 bottles of Coppermelt. One of them has been sitting sine about February of this year at room temperature. I opened it this morning and it had pressure built up. Is this can still good? How long does this stuff last before it no longer cleans as good as when it is new? The other can that I have I have been using since about the same time. It NEVER develops pressure, and I also was heated in the 40 degree sun for a few hours. When I put a few drops on a penny this morning, it barely turned a blue color. Is this can done? Will it still work at all? Thanks for the info.