Insulator Letter Stamp Theory
Letter Stamp Theory
The more insulators I see, the more I find stamped with an individual letter or combinations of letters.
One theory discussed by Derek Milward, a fellow UK collector, and myself is detailed here and is based on the factories within the 'Potteries' i.e Stoke-on-Trent area. Contributions regarding this subject would be appreciated.
It is believed that a lot of hand made insulators, in particular the standard post office variety, where contracted out to agents who in turn, may, have spread the work amongst individual insulator making households.
These would have literally been peoples houses where they used a simple turning machine to create an unfired insulator. Each person would have stamped their work with either a single letter i.e. X or a combination i.e. NR or UV.
These marks either represented the maker or agent directly or, a combination of the two i.e. Agent N, maker R.
The stamp not only gave the agent a degree of accountability for payment but also a means of quality control accountability for the originating company.
It is propositioned that Bullers used this system and it is known that in the 1940's all telephone insulators where quality tested at the request of the Post Office
The standard post office pattern insulator is awash with minor variations in size , markings and even manufacturing techniques, yet many are stamped with the same manufacturers logo suggesting a certain degree of tolerance with design limits outside of a rigid, machine based, factory production line.
Conversely, examination of the standard pothead, No.16, design by Bullers reveals the opposite. They are very uniform and within a very tight tolerance even over a forty year period, (dated examples from 1934 to 1974).
But ... there's always a but.
Standard Post Office pattern insulators stamped with letters as discussed seem not to be stamped Bullers but are usually stamped with the receiving companies name i.e. GWR, Great Western Railway. Does this mean therefore that they are not made for Bullers but another company, maybe Taylor Tunnicliffe as they seem to use a letter stamp and TTC logo on some of their insulators ?