When did Hamilton switch to the composite dials on the 950B? I had a composite one in the past and just bought one with a porcelain 23j marked dial. The serial is S1478 and this points to a 1942 production based on the Hamilton material but it is a 2nd run watch and I am not sure at what point they switched.
Edit - Just a quick search showed me 2 watches S6706 with a porcelain and S6738 with composite. Yet I see a S10467 with a porcelain dial. Confused now. I know that over time watches may have had a damaged dial and a new one could have been ordered that was composite but I am unsure if the factory was turning out both at the same time.
The meeting minutes of the Materials Committee 6-20-46 state on page 5 item 4 that "Mr Shubrooks stated that development work on Melamine enamel dial project was still under way and that consequently present production costs were still higher than they would eventually be."
So post 46 for Melamine and pre 46 for porcelain in general. Still looking......