purple glass jar

[naturegirl]

Hi! We found this jar on a hillside yesterday with the remains of a chevrolet from the 19-teens. We think. I've read about manganese dioxide turning purple, so I think this jar is like that, pre WWI, it has a mold seam and a pontil, so was it blown into a mold? The mold seam does not extend up over the twist-lip, it looks like it in the pic, but I think that is a scratch, or crack. I think the mold seam stops at the lip. When did they start putting twist tops on, and is this a transitional piece, so to speak? Glass is new to me, I'm learning, correct me if I'm wrong on anything. Also found some green peices of a glass bowl that look like the green that glows, haven't got a blacklite. Will this purple glow too?

Thanks for looking

naturegirl

[Harry Pristis]

Hmmm. That is not a pontil scar; it is a valve scar from a bottle-making machine.

Screw-top canning jars appeared in the late nineteenth century. The hand-finished examples have a ground lip rather than a smooth lip.

"green that glows" . . . . uranium glass. Purpled glass will not glow.

[naturegirl]

Thanks Harry, but I got it right that is is purple, right?

ng

[Harry Pristis]

Thanks Harry, but I got it right that is is purple, right?

ng

Right as rain, 'naturegirl'!

After manganese dioxide supplies dried up with WWI, glass manufacturers started to use selenium as a clarifier. Selenium seems to resist alteration from UV exposure, but gamma radiation turns such glass a yellowish amber.

[SODABOTTLEBOB]

Nice Find -

It has always been my understanding that manganese was, for the most part, stopped being used "around" 1915. Of course, there are exceptions to every rule, and a little research would narrow this down.

SODABOB

[Harry Pristis]

Nice Find -

It has always been my understanding that manganese was, for the most part, stopped being used "around" 1915. Of course, there are exceptions to every rule, and a little research would narrow this down.

SODABOB

My understanding is that the British naval blockade of German shipping interupted the supplies of German-controlled manganese. American companies would have used whatever supply they had on hand, then switched to selenium during WWI.

[SODABOTTLEBOB]

Harry -

Thanks for the additional specifics. There's nothing I like better than someone who does their homework.

I think we can all agree that any sun-turned amethist (purple) bottle can be dated "pre" World War I. Of course, that's only the tip of the ice burg in dating most of them. But at least it tells us that it can't be any newer than that.

SODABOB

P.S. And for those that didn't know, it's typically prolonged exposure to the sun that causes those particular bottles to turn purple. And in many cases the longer the exposure to the sun, the darker purple they will get. Something about ultra violet rays. I wish I knew more about the scientific aspect of that, and can see now that I have some homework of my own to do.

[naturegirl]

Cool! Thank y'all so much, between the bottle and the car, I think we have a Pre WWI site. That's exciting!

ng