There does not seem to be an end to the reporting of new Pittsburg date control markings. New reports keep dribbling in with a chunk here and there.

Frank Phelps (Nibley, UT) reported three new full date markings on sim U-680A in October 1985 CJ and has again come up with yet another:

DEC 11 1917 (SIM U-672)

C. B. Dittmar (Attleboro Falls, MA) has reported the following three markings:

SEP 20 A.M. (U-243)
OCT 18 PAID (U-246)
DEC 6 1915 (U-? -- glazeweld 6-7/8 x 5-1/4)

Stephen Corfidi (Kansas City, MO) has reported the following marking on an insulator he found in Baltimore:

OCT 27 PAID (sim U-290)

Also, I found two other markings previously reported in Jack Tod's book Porcelain Insulators - Guide Book for Collectors 2nd edition (1976) on page 136. It always pays to reread the material in his book as it is impossible to recall all of the details. I guess I have read that book over two dozen times and am amazed at finding something for the "first time". The two full date markings are:

JUN 20 1915
FEB 17 1921

With all of these new finds, I have decided to run a revised list of the known Pittsburg date control and full date markings again.

With the new interest shown in these markings, I have tried a new approach at breaking the date control marking code. As many of you will recall in July 1979 CJ, Jack called for readers to report all available markings to test Matt Grayson's theory for deciphering the year codes. This method called for determining Saturday and Sunday dates for each marking in the years 1916 to 1921. By eliminating the years that, for example, A.M. dates were on Saturday or Sunday (assuming the plant was closed on those days), it was hoped that a year could be determined by the process of elimination for each date code. This proved not to be a good assumption and, along with very few collector reports, the project was dropped.

The new approach that I tried was first to find the days of the week for each date code for the years 1916 to 1921. These findings are shown on the following page.

You can see from the full date markings that Sunday was used to incuse mark green-trimmed insulators in the 1915 period. Green-trimming is usually done about 24 hours after the insulators are press formed and then the incuse markings are applied. The date markings have only been reported on trimmed insulators and not on insulators with a prominent mold line. I then made the following assumptions:

1916 and 1917: Eliminate years with dates on Monday since first years of the war would possibly reduce production and presses would not operate on Sunday; thus the marking operation would not be performed on Mondays.

1918 and 1919: Eliminate years with dates on Sunday and Monday due to further decline in production.

1920 and 1921: Eliminate years with dates on Saturday, Sunday and Monday due to further production cutbacks in these depressed years.

Now, referring to the tables of markings, days of the week and years, the year for each date code can be determined by the following sequence of elimination:

1. PAID must be 1917 because it is the only year (for PAID dates) without a Monday.

2. P.M. must be 1916 because it is the only year (for P.M. dates) without a Monday.