PYREX -- an answered question? ? ? ?

Reprinted from "Crown Jewels of the Wire", January 1989, page 24

J. A. Peninger of Shreveport, Louisiana, wrote:

"I have a Pyrex CD 326 (p.352 of Milholland's Bicentennial Edition) and is the same as the one shown, EXCEPT the manufacturer's number is 353 (very clear on the piece) instead of 453 and on the back is a very clearly "etched" (not embossed) the letter B. Can you shed any light on this piece?

Jeff McCurty, Millbrook, New York, answers:

"Your letter of inquiry regarding the CD 326 Corning-Pyrex 453 sum caught my attention. First of all, the Corning Glass Works used a variety of product control methods. Some were a series of dots and some were letters like A, B, C, etc. marked on the insulators. There are numerous examples of both. Corning called these mould markings and not embossings...same thing I know, CGW has no record of these dots and letters with their actual meanings, but it is thought they signified origin of production within the glass works. The "B" on your insulator was written on by hand? I take it that is what you mean by etched. This is not all that uncommon and I have seen other Pyrex insulators marked as such.

"The Corning-Pyrex 453 does not seem to be an overly common insulator when compared with the 171, 401 and 441 units. They are around and in the carnival treatment more than the clear it seems. Either they are still in service someplace or proved to be an unpopular size and were seldom ordered by electrical companies during the 1930's and 1940's. The 453 does appear in the 1930 catalog put out by Corning Glass Works.

"Now...as far as the 353/453 insulator is concerned I have never heard of such an item and found it hard to believe that CGW made such a mistake with their markings. Prejudiced, aren't I?

"I did not have the 1976 issue of Milholland's book handy so I looked up the CD 326 in the 1973 issue. The photo used for the Pyrex 453 is the same photo used for the 353. By the way...there is no such insulator as the 355. Anyway, I then got out my 1976 issue that you made reference to. Milholland used the same photo again for both the 353 and the 453. The photo is of the 353. This is why you think you have a 453 with the 353 marking on it. There are no photos of the 453 in either book, although Milholland represents that there are. The two insulators are of identical shape and design... just different sizes. I have no idea why this was done with the photographs, because there were 453's in circulation within the hobby when both of these books were published.

"Obviously, you have a Corning-Pyrex 353 insulator that is just fine being a CD 324. You did not make any mistake because it is the books that are in error. 

"Good collecting! BY the way...do you have any other pYrex insulators in your collection?