The Sams Photofact for the H-22T155 is set 357, #12 dated 5-57, so it is likely that the sets and CRTs were built very early in 1957, pre-dating the 21CYP22 data sheet. I guess the question to be answered is "When did Corning make FRIT available?" or "was there some early type of "solder glass " that could have been used?" I really don't know, but see no evidence of frit on my CRT.
"And thanks for the link to the excellent photo of the side of your 22EP22!"
You are welcome!... Here are a couple more pix:
http://www.videokarma.org/attachment...7&d=1271460771
http://www.videokarma.org/attachment...4&d=1271460550
jr