# Purple Jar with air bubbles



## moodorf (Apr 23, 2022)

This is the only other ID I have at the moment. Unfortunately, this jar has no identifying marks whatsoever on it. Some scratches though. The bottom has a vague circle shape and some "waviness" but that's about it. However, the jar is slightly purple and has visible air bubbles in it. Any ideas on an age?


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## UnderMiner (Apr 24, 2022)

The circle on the bottom is called a valve mark. This is where the machine pushed the jar out after it was done being formed. This mark is typically found on jars and milk jugs dating between 1900's-1940's. After the 1940's the technology for making jars became more efficient and these marks stopped appearing for the most part.


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## UnderMiner (Apr 24, 2022)

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## East_Tn_Bottle_Guy (Apr 24, 2022)

The purple hue is caused by manganese in the glass. The bottle manufacturers tried to make a clearer glass so they used manganese. Over time UV rays from the sun (it can also be done artificially) reacted with the manganese in the glass and turned it purple. The more UV, the more purple the bottle will be. I've heard contradicting info on when the stopped using manganese, but I would think most stopped before the 40s? Maybe even early-mid 30s? There are threads on the forum that go into more detail if your interested.


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## Phil Younger (Apr 27, 2022)

East_Tn_Bottle_Guy said:


> The purple hue is caused by manganese in the glass. The bottle manufacturers tried to make a clearer glass so they used manganese. Over time UV rays from the sun (it can also be done artificially) reacted with the manganese in the glass and turned it purple. The more UV, the more purple the bottle will be. I've heard contradicting info on when the stopped using manganese, but I would think most stopped before the 40s? Maybe even early-mid 30s? There are threads on the forum that go into more detail if your interested.


I've been told that they stopped using manganese with the onset of WW1, as it was needed for munitions. That being the case, it would date this bottle to pre 1918


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## Dogo (Apr 27, 2022)

I was told that the manganese came from Germany and the supply stopped at the beginning of WWI


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## moodorf (Apr 27, 2022)

Makes sense since I read manganese being used ended in 1920/very early 20's--after 1918 manufacturers must have had to burn off their stock which could have taken a little bit.


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## CanadianBottles (Apr 27, 2022)

moodorf said:


> Makes sense since I read manganese being used ended in 1920/very early 20's--after 1918 manufacturers must have had to burn off their stock which could have taken a little bit.


Yeah its use seems to have fizzled out around the early 1920s.  It wasn't a sudden stoppage like people tend to think, but it did become harder to source in WWI so it was mostly phased out around then.  Manganese didn't come from Germany like is commonly believed (I don't think it's found in the country at all) but the disruption of supply lines due to the war did make it difficult to acquire in North America since it was typically shipped through Europe and then across the Atlantic.


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## Harry Pristis (Apr 28, 2022)




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