# Do Sun Colored Bottles Fade?



## passthebottle (Aug 21, 2010)

That is something that I always wondered about. I have a number of sun colored bottles packed away in boxes  and it seems to me that when I look at them from time to time they seem to be losing some of their color. Does the color fade over time if the bottles are not left in the sun ?


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## GuntherHess (Aug 21, 2010)

dont think so.


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## cyberdigger (Aug 21, 2010)

Exposing them to moonlight takes the purple out.. or so I've heard.. []


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## RED Matthews (Aug 22, 2010)

Hello all of you.  I first ran into SCA   Sun Colored Amethyst, on a trip to California.  Out west I would see bottles laying on wood shed roofs.  When I asked about this practice, I was told about the action of the sun.  I looked it up and learned why this happened.  I have several fly traps that are SCA and last winter I hung a nice clear glass fish net float on the front porch and it colored up great.  I will only happen on clear glass that was made before about 1913 and is the result of manganese in the glass batch.  The 1st World War turned off this element for use in the glass batch.  When used it was to improve clear glass control and to help in the molten metal forming ease.  RED Matthews


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## Jody35150 (Aug 22, 2010)

You know how you 'hear' things...   I had always heard that if you heated a bottle with the purple tint, it would return to its' original clarity.

 I tried it on a whiskey bottle which had been irradiated;  it was the dark unattractive purple.

 Left it in the oven at 300 degrees for a while, and forgot it was in there.  Re-heated the oven to 400 later, only remembering the bottle when the preheat indicator sounded.

 In the end there was no change in the degree of tint.

 The naturally sun-colored glass, as described by RED Matthew, is in my opinion the most beautiful.


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## RedGinger (Aug 22, 2010)

I wouldn't think they would fade.  It's not like a sun tan.  It's a chemical reaction in the glass.  It's kind of cool because it can help date a bottle.  Some people really like that amethyst color.  I think the lightest hint of it is pretty if I find an old bottle like that.  I wouldn't sit it in the sun to develop that color, though.  That's just my personal preference.  Some people like to sit them under lights to make them a darker purple.


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## JOETHECROW (Aug 23, 2010)

Here's the only info I'd run across pertaining to reversal of sun coloring...

*Thermal Reversals of Authentic Colors (Reversing Sun-Purpled Insulators):* 

 It is an established certainty that most, if not all, light to medium purple _California_ embossed insulators emerged from their factory molds in shades of off-clear, yellow, smoky yellow or light yellow green; and the darker purple/deep burgundy examples were most likely golden yellow. Light to medium purple _WGM_ insulators were originally clear, off-clear, straw or light yellow green. Since weâ€™ve already learned that manganese-bearing glass will react to the ultra-violet rays of the sun, we now know how and why the preceding examples were naturally transformed to varying shades of purple. We will now investigate a practice that has been performed by some unscrupulous individuals to reverse this natural purpling process, in some instances for monetary gain due to the rarer and more valuable resultant colors.   

 Exposure to high levels of heat will reverse the sunâ€™s ultra-violet purpling effects on glass. This procedure is often referred to by collectors as â€œcookingâ€. During the thermal reversal or â€œcookingâ€ process, the manganese is once again the key stimulant. In most cases, when a sun â€œpurpledâ€ insulator is heated to high temperatures, generally a step below melting, it will revert back to a shade in close proximity to its original manufactured color.   By Reintroducing a "cooked" insulator to direct sunlight the natural purpling process will begin to occur once again, although the resultant color tones may differ from the original.  Be aware that deliberate partial exposures can create artificial two-tones as well.


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## ktbi (Aug 31, 2010)

If I set a clear glass bottle out in the sun, how long does it take for the purple to start showing?
 Thnks.....Ron


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## blobbottlebob (Aug 31, 2010)

Hey Ron,
 My guess is a very long time. The bottles that I find in amethyst have been in the water for 100 years (and they aren't that dark). I leave a few in the windows in the hope that they are darkening. Maybe someone could do an experiment? Take two bottles, identical in coloration and put one out while the other stays boxed. Might be interesting???


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## Plumbata (Sep 5, 2010)

Dunno about the fading part, but the latest SCA bottle I've seen was a TMFG CO milk with what I imagine was the date of 1916 on the base (a 16). Perhaps a late holdout made with the remnants of old manganese stockpiles?


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## GuntherHess (Sep 5, 2010)

> Exposure to high levels of heat will reverse the sunâ€™s ultra-violet purpling effects on glass. This procedure is often referred to by collectors as â€œcookingâ€. During the thermal reversal or â€œcookingâ€ process, the manganese is once again the key stimulant. In most cases, when a sun â€œpurpledâ€ insulator is heated to high temperatures, generally a step below melting, it will revert back to a shade in close proximity to its original manufactured color.   By Reintroducing a "cooked" insulator to direct sunlight the natural purpling process will begin to occur once again, although the resultant color tones may differ from the original.  Be aware that deliberate partial exposures can create artificial two-tones as well.


 
 I know you cant do it in a conventional oven. Thats already been tried.
 I havent done an experiment in a glass kiln (we do have one here).
 Problem is the insulator (or bottle) turns into a puddle if you get it too hot.
 Also the cooling cycle can be tricky and the glass often cracks. 
 I may do an experiment to verify this.


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## cyberdigger (Sep 5, 2010)

Cool! make another one of those candy dishes!! [8D]


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## cyberdigger (Sep 5, 2010)

[]


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## GuntherHess (Sep 5, 2010)

> make another one of those candy dishes!!


 That was my wife's strange experiment.


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