Conservation Glass?

[prospero]

Had a question from an artist customer today. I framed a large charcoal drawing recently which he sold. The buyer asked if it had "conservation" glass in it.

The answer is not straightforward though..

It had bog-standard ordinary cooking grade 2mm float glass. But given that this glass is protecting the work it could be described as conservation. AR glass would make it nicer to look at, but is not actually going to conserve the work any more than than standard. Museum glass would filter out (some) potentially harmful light wavelengths but given that charcoal is about the most permanent media you can get, it really doesn't justify the cost of a sheet IMHO. It's drawn on light grey mountboard. This may fade a tad over the years but isn't going to change noticably. It isn't going to fade back to white. And there's no guarantee that Museum glass would stop it anyway.

So what answer would you give?

[IFGL]

I would tell the customer what you have just posted, also that if they had any concerns we could add CV glass and I would also give the customer a art care leaflet and let them know we can add that too if they thought it would give them more peice of mind.


P.S for those framers that do use artcare there is a pdf download of the leaflets, which describes the benifits of it on our website.

[huntvambo]

Tru-Vue Conservation Clear isn't that expensive.

Tru-Vue Museum Glass is expensive but if they're only concerned about conservation...

[prospero]

My thought was that any "Conservation" type glass isn't really going to provide any benefit from a preservation aspect. Given that the image is in BW to start with.

The standard glass that is in it is protecting it from muck and physical damage so is that not conserving it?

[IFGL]

Yeah but so would a bit of pilot gene, the CV glass should give it a longer life even if it's only the card backing it's protecting, it should slow the process of the board breaking down, probably not by much.

[Roboframer]

The answer is not straightforward though..

Yes it is, you've either used conservation glass or you haven't; you didn't!

It had bog-standard ordinary cooking grade 2mm float glass

Therefore

So what answer would you give?

"No, I did not use Conservation Glass"





.

[prospero]

Granted.

But given that standard glass will conserve the work could it not also termed 'conservation'? As opposed to no glass at all.


Anyroadup, if they ask for Conservation/Museum/AR glass they won't find me wanting.


(If it was mine I'd put AR glass in)

[Roboframer]

I think it's best kept simple, there are standards set for conservation glass, by the FATG, by the PPFA, by other more obscure organisations like the IPI (Image Permanence Institute) and there's an ISO.

There are also plenty of products with a very high level of UV protection that might not quite hit those standards that are at least made with protection in mind and, when referring to glass as 'conservation' you really should be referring to its level of UV filtration, nothing else.

Therefore the answer is still a nice-and-simple, no-ins-and-outs-of-a-cats-arsehole ..... "No"!

[prospero]

Yeah that what I told him. The artist not the cat.

[Roboframer]

The standard glass that is in it is protecting it from muck and physical damage so is that not conserving it?

Aha! You have seen the light at last and will be offering to glaze oils on canvas now?

[prospero]

You want glazed oils? I got glazed oils.

[Otters Pool Studio]

AR glass would make it nicer to look at, but is not actually going to conserve the work any more than than standard.

Most AR glass (Artglass, TrueColor) will filter 60-70% UV rather than the normal 40-50% UV of standard float, so in fact it would conserver more, but not as much as Conservation Clear (for example) at 98-99%.

[prospero]

All good scientific stuff, but....

If something is liable to fading all UV filtering will do is postpone the inevitable. It's all a matter of degree. Two identical prints, one with std glass, one with 'conservation' will eventually reach the same level of exposure to harmful rays.

[strokebloke]

I would explain my premise to the customer, as you have done in the initial posting.
I would then ask him what type of glass he would like, to set his mind at rest; being diligent in pointing out the cost implications.
Then I would follow his instructions accordingly.

The job's a good'un
He's happy. You're happy. And presumably the artist will also be happy, because you have demonstrated that you understand the implications of the matter: both artistic and commercial.

[Not your average framer]

If ordinary bog standard glass filters out 60% of the harmful UV radiation, it therefore follows that it lets the other 40% through. If on the other hand if UV filtering glass only lets 1% of the UV that's a 40 t0 1 ratio. Unfortunately, some types of paper (including paper sold in art shops) can become darkened over time with exposure to both light and UV. Both are damaging, but UV light is substantially more damaging than visible light.

Over time as the paper darkens, there will be a reduction in the contrast of the image relative to any areas of exposed paper and some customers may decide to get their charcoal drawing cleaned to restore the original appearance. As most will imagine, cleaning a charcoal drawing is not a nice and easy thing to do and the cost of having this done will not be insignificant either. As a result the use of UV filtering glass may turn out to make a lot of sense, particularly in financial terms after all.

Not only this, there is a threshold effect in the degradation of paper where below a certain level, there is not enough UV radiation to trigger chemical processes which degrade the paper and good UV filtering may result in a difference of protection (in terms of years) which exceeds the 40 to 1 difference between the two types of glass in filtering UV radiation.

This threshold effect is also temperature dependant and as such is a good reason to avoid hanging works of art where they may be subjected to increased ambient temperatures. Better quality paper also has a significant impact on this same threshold effect due to the reduced level of unwanted chemical impurities which can change state when a certain energy threshold is reached.

This threshold effect is called the band gap, or energy gap and is an energy range in a solid where no electron states can exist. The term is well known in solid-state physics (Quantum theory) and also in chemical proccesses where the specific chemical process is temperature dependant. Many high value works of art of recognised importance are stored in darkness and low temperatures for this very reason.

BTW, fading of colours, or darkening of paper does involve chemical changes, even though the level of ambient radiation is the primary initiating cause. Also the rate at which these chemical changes accelerate in response to the level of energy is not linear, but approximately logarithmic. In most cases the level of unwanted activity doubles for every 20 degree centigrade increase in the anbient temperature and most high precision analogue circuit design engineers, physics scientists and research level chemists are required to be aware of these issues.

The band gap effect is so small in terms of measurements that it is easy for many to assume that it does not have a significant effect on the world we live in, but in reality it is the reverse which is true! Fortunately for us, we live in an age where technology is able to remove unwanted impurities from so many materials and we are able to measure levels of naturally occurring radiation and where this radiation produces unwanted consequences, we now have affordable technology available of the shelf to filter, or block this radiation.

UV filtering glass, conservation mountboards and high quality art materials have pretty much taken that which is possible to the highest levels which the laws of science will allow and the advantages of using the full range of protective framing materials as a full package is very compelling. Added to this, the cost of adding UV filtering glass to customers smaller artworks is becoming all the more persuasive than ever as the cost of UV filering glass is driven lower by competition between the various brands. I hope that this is going to be a really meaningful discussion of real and practical value to us all.

[IFGL]

A very long post Mark, but I do agree, not everyone can comprehend percentages and get cought up in numbers that do not mean much in reality.

I have tried to explain uv in viable terms before by comparing to AR Glass

Normal glass 92% light transition 8% reflection
AR glass 99% light transmission 1% reflection.

Does not seam that much difference but in reality it is x 8 difference a massive amount, and massively visable.

[prospero]

The plot has thickened a tad since first I posted. It seems the customer who bought the framed drawing was a dealer and from what I gather was angling get a free upgrade.

But the whole thrust of my argument is that half-informed buyers may get the impression that putting "conservation" glass over a work will conserve it. This is true in a lot of cases but not all. Depending on the substance of the work it may not have any beneficial effect over standard glass.

[Roboframer]

Not really - this was the main thing

The buyer asked if it had "conservation" glass in it.

and the answer was a simple "no" - it really was that simple and would have been my answer.

If ordinary bog standard glass filters out 60% of the harmful UV radiation, it therefore follows that it lets the other 40% through

It's much less than 60% - 47 or so I think.

UV light is substantially more damaging than visible light.

It may well be but apart from what UV light we provide artificially, it also comes as part of the package from the sun/sky and if you expose artwork to direct natural light it's screwed - or at least some of it could be (it's a total minefield really, isn't it!) like my pastel on the other thread - the actual artwork ... what the artist did, is absolutely fine, but not the paper - maybe not any mount either.

Fluorescent light is high UV apparently but my shop is full of bare tubes with no diffusers and they don't seem to cause a problem - the window on the other hand, from about now until end of September the display needs changing twice-weekly if it's not mirrors!

I've said it before but WHERE you hang stuff is the most important factor - if it's in the IDEAL place, it might not need UV glass at all - if it's in such a non-ideal (bad)place that it really MUST have UV glass - it's gonna fade - and well faster than the same thing in the ideal place with standard glass. Prevention's always better than cure.

[Not your average framer]

It's much less than 60% - 47 or so I think..

I was including some of the anti-reflective coated glass in this figure.

UV light is substantially more damaging than visible light......Fluorescent light is high UV apparently but my shop is full of bare tubes with no diffusers and they don't seem to cause a problem

The phosphor coating inside the flourescent tube turns much of the shorter UV wavelengths into visible light, due to these shorter wavelengths exciting the molecules in the phosphor coating.

To get any significant level of long wavelength UV from a flourescent tube, the tube is filled with a different type of gas, which will produce a completely different UV spectrum.

I suspect that some modern low energy spot lamps may put out quite a bit of UV compared to the usual flourescent tubes, but I've never had much to do with them so I don't know which wavelengths of UV are generated by these.

[Roboframer]

I was including some of the anti-reflective coated glass in this figure.

Not in your post, you said 'bog standard glass'