Your probably correct about the, being used for printing. They haven't used glass for many years. There would have also been a Red(Magenta), Blue (Cyan) and a Yellow one. Known as CMYK (Cyan, Magenta, Yellow, Black) The plates were probably produced in Racine, Wisconsin. -Steve Santi
I have found some glass templates or lithographs. One is for the cover of the Pokey Puppy with the bind print. They are glass with the black picture like what should be used to print the cover of the books. I can not find anywhere on the internet where these were made, what they are worth. I found them in an old barn. Most of the glass templates were broken. Can anyone help me with any information about these templates/lithographs? I would truly appreciate it. Thank you.