I recently came into the position of many of these glass "things." I believe they're glass positives used for offset printing, but I'd love to learn more. Heck, I'd like to know that I'm wrong, and educate myself.

I have them in many sizes: 18" x 18" up to 24" x 36". They are very heavy. I've only looked at a few. I would date them from 1940 - 1970, and maybe older.

Once I figure out what they are, I'll explore what to do with them.

Thanks.

I recently came into the possession of many of these glass "things." I believe they're glass positives used for offset printing, but I'd love to learn more. Heck, I'd like to know that I'm wrong, and educate myself.

I have them in many sizes: 18" x 18" up to 24" x 36". They are very heavy. I've only looked at a few. I would date them from 1940 - 1970, and maybe older.

Once I figure out what they are, I'll explore what to do with them.

Thanks.