Yes, because of its age it is difficult to cut, but I have not had any problems with grinding . The plates I have are only 4x5, so handling is not too much a hazzard. I like to use them because thay do not have a tint, are thin; about 1.5 mm, and they do make nice bright screens.
I do have a source for new optical glass that has both these qualities, Schott B270 Drawn Crown Glass from: Howard Glass in MA,
www.howardglass.com. It comes in .9mm, 1.15 mm, 1.65mm, ect. they will cut to any size, have low min order, will grind but expensive ($100 for one), and limited to 4x5.
I would like to find a source for new ground optical glass. There are companies in China that have green acid etched glass and huge min. orders, not really what I what. Does anyone know of a place?
I do agree that one or two, or even 5 plates would not have that much silver. I have over 100 of these plates so it might be worth while to havest. I would like to use in Van Dyke process.