Conservation Glass Update

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Terry Scidmore CPF

MGF, Master Grumble Framer
Joined
Jul 5, 2001
Posts
691
Loc
Seattle, WA 98168
I wrote recently about my glass sampler that appears to have faded about equally under both the conservation glazed side and the nonconservation glazed side. A number of people made suggestions about why this may have happened and I have been checking out the suggestions as best I can. The company who made the glass tested the glass recently. They reported back that the conservation filter was working to the percentage that it should. Their conclusion is that the fading is due to visible light, not UV.
Does anyone know which is more damaging to art -UV or visible light? (Hugh - I hope that you will step in and shed some light on this!)
Thanks for any input that anyone can supply!

The conservation clear glass tested out nearly 100% UV blocking below 370 nm, 97.7% at 370 nm, 96.8% at 373 nm, 90% at 381 nm, 40% at 400 nm. The company was very kind to test the glass and explain their testing proceedure and the results. They will send the test results for the other glasses soon.
Briefly, all the glasses tested out at the ranges for blocking UV that the company states that it does.

[This message has been edited by Terry Scidmore CPF (edited July 30, 2001).]
 
Terry

What percentage do they say the filter is working at.
I'm trying to interpret the Schott Glass brochure, the suggestion they make is that if the UV filter is around 300nm wavelength there should be no problem where or how the art is displayed.
Schott supply there glass to many of the museums and galleries across Europe including the Tate Gallery in London.
Despite having had a business selling glass to picture framers in Ireland and earlier in my career selling optical equipment I quite frankly have never received a clear answer to the question of UV protection.

Dermot
 
Sadly, there has been too little work done to
classify which materials are vulnerable to
fading in UV and which fade in the visible
range. I have been urging conservators to do
more research on this topic and the related
topic of which materials will not fade in
oxygen straved atmospheres. Lignin will darken and degrade in UV and cellulose will
beach in the near UV blue portion of the
visible spectrum. One of the best sources of
information on this topic is the listing that
paint manufacturers post about their paint.
Windsor/Newton and Daniel Smith are good on
this subject. The difficulty comes in knowing
which colorants are present in the work with
which we are presented. The same pigment will
be more durable in a thick layer than it will
as a wash and will be more durable in oil than it would be as in a pastel or watercolor. Printing materials from web presses are generally fugative, unless special ink sets are used. The whole topic is
so complicated that you have inspired me to
go back to the notes I have taken over the
years and try to do it some justice in the
future.

Hugh
 
Hugh,

Thanks so much for a response. Even that much helps us, or some of us, address the problem with a bit more knowledge than before. Any further information you might share would be very welcome. This is becoming a credibility issue, I believe.
 
And what about all the new printing processes out there? Some claims I've seen for some of the newest ink jet printers have been for 200 years, but they don't say under what conditions or what will fade them. Technology is changing rapidly. The only thing I have read a bit about is that color photographs are more prone to fading by visible light than UV, but it depends on the brand and type of paper printed on and the manufacturers keep introducing new ones!

------------------
Anne LeBouton
 
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