I agree with everything that Ralph says, as usual. Where's the check, Ralph. One condition I have never not encountered in older glass when removing it is the inescapable variation in thickness, which, fabrication aside, occurs, so I am told by those much older (few left) and wiser (of which there are legions) that due to the liquid nature of glass, it "creeps", flowing somewhat to the lowest point in an assembly, resulting in somewhat thicker glass at the lower end of a light than at the top. Is is also more brittle. V.I. -- To terminate puerile preservation prattling among pals and the uncoffee-ed, or to change your settings, go to: <http://listserv.icors.org/archives/bullamanka-pinheads.html>