Author Topic: PW has yellowed glass!  (Read 340 times)

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Offline CML

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PW has yellowed glass!
« on: July 24, 2013, 07:14:07 PM »
Well .......my first mistake in buying on eBay, but not the only one:

I received a Paperweight that the seller could not identify it's signature. I bought it and to my surprise it was a Rollin Karg signature. The glass seemed a little faded yellow--I just thought it went back to his earliest pieces....the more I think about it --this shading could be from sunlight or smoke, right?

Is this why sellers post "from a smoke free environment"? DUH!

Let me know what you think.
TIA


Offline Lustrousstone

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Re: PW has yellowed glass!
« Reply #1 on: July 24, 2013, 08:19:37 PM »
You have checked that the surface of the glass is clean. Discounting water staining or the effects of burial (which are chemical effects), the only thing that will affect the colour of glass beyond the surface is UV light, but only IF the glass formula contains manganese. It was probably an inferior glass batch

The only things smoke free is important to are textiles, paper, leather, and porous surfaces, etc. that will actually absorb the smoke, and things that cannot be washed. Have you ever seen clean window glass that was yellow?


Offline LesBeatiques

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Re: PW has yellowed glass!
« Reply #2 on: July 25, 2013, 01:34:54 AM »
At times I've seen the surface of the glass reflect back the inner core which plays a bit of an optical trick making the rest of the glass seem to have color....Could this be the case?

Regards,
Eric


Offline CML

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Re: PW has yellowed glass!
« Reply #3 on: July 25, 2013, 05:02:53 PM »
Thanks for your replies. I know what you mean about the reflected color of the design, but that does not seem to be the problem. I think it had been exposed to a great deal of sunlight. This will make it less valuable ,right?



Offline Lustrousstone

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Re: PW has yellowed glass!
« Reply #4 on: July 25, 2013, 05:40:33 PM »
Sunlight will not yellow glass, though it might turn it grey or lilac; look up sun purpling


Offline KevinH

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Re: PW has yellowed glass!
« Reply #5 on: July 26, 2013, 12:39:02 AM »
I do not know the technical reasons, but yellowed glass may be caused by too small a proportion of decolourant in the batch.

Even weights made by Paul Ysart (one of the world's best paperweight makers) had a yellow tint in one period (circa 1940s).
KevinH


Offline CML

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Re: PW has yellowed glass!
« Reply #6 on: July 26, 2013, 05:24:48 PM »
Thanks Kevin. I feel much better knowing this might be the glass itself and not damaged.


Offline Fuhrman Glass

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Re: PW has yellowed glass!
« Reply #7 on: July 26, 2013, 06:35:23 PM »
If the glass has a yellow hue to it, and is perfectly clean then that's the way it was when it was made. The glass did not change color by being exposed to UV or any thing else. Some borosilicate glasses can change colors depending upon if you pass it thru an ionization process. This was patented by Corning many years ago and the technology sold to a smaller company in Ohio. I used to have clear borosilicate items ionized and it turned a very deep ruby red that was not just in the surface but went entirely thru the piece. They did lots of earlier tail light lenses, lamp and lighting wares and candleholders that way besides creating nice rubies for lamp workers.
If you want, contact Rollin in Kansas and quiz him about he. He's a very nice and accommodating gentleman.


Offline CML

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Re: PW has yellowed glass!
« Reply #8 on: July 26, 2013, 06:49:39 PM »
Wow! Thank you for the lesson and suggesting I even contact the artist. I have several Kargs and a large sculpture. What you say makes sense and I love his work no matter what.

Thank you


 



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