hey all... another rookie here.. just one question. i've been playing around with a few patterns on some pieces of scrap leather and one thing that i am noticing is that every now and then while i am beveling an edge the leather is turning almost a green or black color and it is only in a few spots, not on the whole beveled edge. no rhyme or reason to when it is going to do it. could it be that it is just a bad piece of leather or is the water that i am casing with "hard water"? would it help to use distilled water to case with? thanks in advance....