by Shawn143 » Sat Sep 03, 2011 9:17 pm
Welcome to the site. Nice looking insulators, them GTP in light purple, not worth a huge amount, but a beautiful colour. Gerry, are you sure with the 20's timeframe? I thought most (if not all) glass manufacturers stopped adding manganese around 1913, since with a war looming, had better uses or couldn't get it. I'm not positive about all glass houses, but Dominion stopped adding manganese to their CROWN fruit jars around 1913, so if you find a real purple one, you know it predates 1913. I'd guess they did the same thing for their insulators.
Shawn