Posted 7 years ago
fortapache
(3296 items)
Back before 1915 Manganese was added to glass to make it clear. It stays clear as long as it isn't in sunlight as it turns purple in sunlight.
According to the dealer where I bought the bottle Manganese came from Germany and because of WWI the US stopped importing it. I am not certain this is true but seems likely. Manganese ceases to be used in the early 1900s.
In addition to sunlight the glass can also be irradiated to turn it purple. There is some argument over if this is good or bad. Myself I figure if it is something common like medicine bottles or something that would normally get a lot of sunlight it is not a big deal. For EAPG I would definitely not do that.
I do have two other purple glass pieces I will post soon.
Thank you very much Jancal20.
Thank you
Oroyoroyisthatyourhorse
mikelv85
bottle-bud
iggy
Caperkid
Jancal20
Lamplover78
JImam
buckethead
kyratango
The person's info is almost correct. You see sun-coloured-amethyst (SCA-- what we call it in the bottle world) glass in the Continental U.S. until about 1920. Most of the Manganese came from Germany, but we had plenty over here. Other decolourising agents were found during the war era that quickly replaced Manganese. Occasionally, you will see 1930s milks slightly coloured. I think their Manganese was accidental and from the same glasshouse, though I know not who.
This bottle has been artificially irradiated. Food sterilisers are often used to do these en mass. A lot of air purifiers have a harsh UV bulb that should do the same thing. Supposedly this process can be somewhat reversed, by slowly heating the bottle to, like, 400 degrees for a few hours-- reversing it but leaving the glass slightly straw-coloured. I've not tested it.
I am against the process as many people think they have an original purple bottle, when it has been modified in the last 30 years.
Naturally irradiated glass-- which can happen through walls and under-ground even as it's not by light, but by another type of radiation-- gets only a few shades darker than this, but usually more like this:
https://www.collectorsweekly.com/stories/176728-michigan-north-dakota-its-a-town-bot?in=collection-6149
By a few shades darker than this', I mean the bottle in my link. Yours has been artificially coloured.
Thank you SpiritBear for the more detailed history. Apparently it is trendy now and some valuable pieces are being devalued by getting turned purple.
Any volunteers to see if using the oven at 200 degrees will reverse the effect? That is something I read.
Thank you
vetraio50
nutsabotas6
Thank you blunderbuss2.
Thank you aura.
Thank you SEAN68.