I have some 49mm and a 77mm PL filters and tried to clean one of the insides of the 49mm one day. Well, that did not work. I put a chip on the edge of the glass and still didn't get the thing apart. It didn't have any fungus inside, but I just wanted to see if I could clean it. I figured that if it ever got real bad I would just toss it. Now that I have a 77mm, it is a different situation. Those things cost $60-80 and I can't afford to toss that every so often. So my question is, how do you take one apart to clean it? My guess is that those are put together with one being heated and one cooled, then as the heated one cools it fits the other. Or, they are just pressed together at high pressure. However they are made, I would like to know if there is a tool or some good way to disassemble them. How do you do it? Thanks.