Question Difference between 70% UV filtering and 98% UV filtering

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Terry Scidmore CPF

MGF, Master Grumble Framer
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Seattle, WA 98168
My customers asked this question, and I can't find an answer, so maybe someone here can supply one.

They are framing one of those large vintage posters. They are paying a lot for the frame and other stuff, and don't seem to be real hung up on price.

But they want facts.

I explained about UV filtering, the range the filter works in, the bit about all light will affect the art, so the less light the better, blah, blah, blah.

They are not asking about the filtering range, but how significant is the difference between the protection of 70% UV filtering (regular acrylic) and that offered by UV acrylic at about 98 - 99%. In other words, what does 28% or 29% mean in filtering.

The "more is better" approach just isn't cutting it.

I thought I remembered reading something about this in a past post, but I can't find it now. I looked at the manufacturers info, and it doesn't address a question like this.

Thanks for any solid info you can supply!
 
Define what you mean by "significant". What kind of answer are you looking for? Some kind of direct fading comparison under controlled circumstances where X piece has faded A% while Y piece has faded B%?
 
I don't know that you can answer a question like that.

To give a quantitative answer one would need to know the lighting where it will be displayed, whether windows and lights are UV filtered and the light sensitivity of the printing inks and the kind of paper fibers and sizing.

Wood pulp and alum rosin sizing will darken with light, cellulose molecules are broken by light, dyes, and some pigments are quite sensitive to light. UV is high energy, so accelerates damage and adds nothing to our visual perception, so filtering it is good general practice.

Nothing is benefited by permanant display...

My guess is there will be at least some dye component in the inks, and the paper likely has groundwood content, and likely has alum rosin size.

If the display area will have UV filtered light sources, it might not make sense to use UV filtering plexi too, but is the price difference that great?

http://www.conservationphysics.org/detcell/detcell.pdf
http://www.conservationphysics.org/fading/fade.pdf
http://www.amazon.com/Painting-Materials-Encyclopedia-R-Gettens/dp/0486215970

These references are all old, but still valid and might be scientific enough for your clients.

Or you can always refer them to a conservation scientist, as at CCI...
 
In other words, what does 28% or 29% mean in filtering.(?)
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After searching years for similar information, I don't believe there is a clear answer. The variables are infinite. In such conversations, the focus is on the ability of the glazing to remove certain frequencies of light, and the test results are precise, in terms of what percentage of the light is removed at each frequency. Trouble is, intensity of the light is unknown. So, if 98% of the light is removed at 322 (or whatever) nanometers, that means 2% gets through. Now, is that 2% of 5 lumens, or 2% of 10,000 lumens, or something in between? The intensity of light in every frequency could be measured at the display site, at various times of day, so this question could be answered with some certainty. But how would that information help?

What about the item under the glazing? How light-reactive is the paper? How light-reactive is the image applied to it? Are all of the inks of that vintage poster going to react to all frequencies of light the same way? If one or more of the ink colors is particularly vulnerable to damage from light at, say, 378 (or whatever) nanometers in the UV range, then perhaps UV filtering could make a tremendous difference. Or, if the inks are equally reactive to light in the visible range, which is not blocked, then maybe UV filtering would not help much.
 
The "more is better" approach just isn't cutting it.
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Actually, the approach ought to be "less (light) is better".

If the conversation is about more protection from the framing materials, the emphasis is backwards. That is a discussion about the framer's responsibility, and you lose, because you have zero control over the frame after it leaves your shop. Instead, focus the conversation on the importance of less light exposure. That places the responsibility where it belongs; on the owner/custodian who has control of the frame's handling, transport/storage, display environment, and maintenance.

The best any framer can do is recommend display in minimum light conditions, and inform customers of these well established facts:

1. The best protection available to reduce light damage is 98% - 99% UV filtering glazing, and its protection is limited.

2. All light exposure is harmful.

3. Damage depends on the duration of exposure and intensity of the light.

4. Light damage is cumulative and irreversible.
 
This subject relates to my question on another thread http://www.thegrumble.com/showthread.php?t=49306 about the difference / comparison between Museum Glass and Schott's Mirogard.

Andrew Perry (CAFramer) mentioned the difference seems to be in their UV filtering. Mirogard comes in 48%, 84% and 99% UV filtering versions.

I personally think that, given the same location on a wall, not in direct sunlight (where nothing will really help), the difference between 70, 84 and 98% UV filtering is not significant enough to be losing sleep over.
 
I know this will sound quite simplistic but the difference between 70% and 98% filtering is 28% more filtering.

The 98% one filters out 1/3rd more of the harmful rays than the 70% one.
If someone wants the most protection they can buy then the 98% is the best they can buy.

As to how much longer the art will last, that still depends on where they hang it.
 
Given the context of this question, it may be worth noting that (according to Tru Vue) FF3 Acrylite filters 66% not 70%.

Given they cite 98% for OP-3, the spread is actually 32 percentage points.

Created by the Image Permanence Institute with support from Tru Vue, here is a really useful consumer guide that touches on this issue.

Should they want to dig deeper they could acquire a copy of ISO 18902:2007, which is referenced in the above article as recommending glazing that blocks at least 97% of UV energy.
 
That's a great article Andrew, thanks!

BTW, did you check out the Dew Point Calculator in the Image Permanence site? It give you "days to mold" for any given set of conditions. Very cool.
 
Many thanks!

I really appreciate the answers and references all of you have provided! This will help a lot!!!!

They want a specific answer - xxx amount is the difference. I have explained how complicated providing an answer can be since there are so many variables - many of them are unknown to us as framers since we cannot control the environment the item will be hanging in, can't determine the ink sets used, etc.

I have covered the less light is best aspect - using TV suggested "low light is best even with conservation glazing. Low light is defined as a hallway or a bedroom with light filtering drapes."

These are young people, and I find younger people are often comfortable with explanations that boil it all down to choice A = x, x, and x benefit, choice B = xx, xx, and xx benefit, and choice C = xxx, xxx, and xxx beneift - like how you would evaluate electronics or appliances.

Since this is not a situation that can be reduced to such simple factors, and my usual explanation was leading to more involved questions such as this one, I thought I should see if someone else had sources that I hadn't stumbled on yet to share with them.

Thanks again so much for your input! I'll check these out and see if I can provide an answer that satisfies and still illustrates why we can't give them a definitive answer.
 
If they go with the lesser, for lack of convincing data. (they need a real life) If or when the art fades, what is the value then to have that thought "what if I had just accepted and gone with the better???"

The easier thought/question is down the road as they continue to enjoy their piece, is: "What would have happened with the only 70%?"
 
Yikes, Rebecca - I don't think I would want to see a Dew Point Calculator. Relative humidity is 81% right now inside my house and has been in that range for months or maybe even years. 'Splains a lot, eh?

Did you know mold grows on picture glass?
 
Terry Scidmore CPF said:
They want a specific answer - xxx amount is the difference.
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And that is a fair request. Unfortunately, and for no good reason, we have nothing to offer. Surely there will never be any way to determine how their specific items will age under their very specific situation. However it would be nice to crack open a book of 100 or so different media types/ lighting conditions/ uv protection levels.

Again that would not hold up to the most demanding request. But it would go a long long long way toward helping a client make an informed decision.

My hunch is that the benefits don't hold up well to close scrutiny and that is why "more is better" is the main tool we are offered.

Good luck Terry and please let us know how you solve this issue.
 
Ok, I just remembered - Museums Canada and the Canadian Conservation Institute did just what Jay asked, and published a poster showing samples of various media:
good quality artist's oils and watercolors ca 1925
colored drawing inks used commercially, ca 1925
dyed textiles ca 1910
colored printing inks ca 1925

and exposed them to known quantities of unfiltered and UV filtered light - there is a table on the poster so that one can quantify the results.

The poster is titled "Put it where the sun never shines"

I don't know if it is available anymore, but you might try calling CCI. In a pinch I can loan the poster to you if you promise to return it; it is 15 or so yrs old, and never been displayed, but who knows what dark fading it has undergone lol.
 
Rebecca's note reminded me that CCI used to have a "Light Damage Slide Rule" that could be used to calculate light damage to an object ahead of time, and determine variations resulting from changes in intensity and duration. It would be worth a call to CCI to see if they still produce it. It might be of interest to your curious couple!
 
So I'll mix it up a bit.

70% UV filtering and 98% UV filtering of WHAT?

Seriously- the percentages are useless unless one states what the 70% and 98% represent. 70% filtering of ALL UV? 70% filtering of UV light within a certain part of the UV spectrum?

Is one specification a percentage of the entire UV range while the other is a percentage of a specific set of frequencies? (between x and y nanometers?)

It is important to remember that we are talking about a light spectrum that is expressed in a logarithmic scale. So, each point up or down is much more significant than a factor of one.

To accurately compare specifications from various manufacturers, it is important to determine if the blocked filtering is a percentage of the SAME percentage of the scale.

And, UV light is only ONE component of fading. ALL light contributes to photochemical changes. The maximum protection of artwork is achieved by not only blocking as much of the UV spectrum as possible, but the reduction of total exposure to all light, protection from ozone, heat and changes in relative humidity.

Items framed with UV filtering glazing will most likely still fade.
 
Tell the customer you will need them to provide some specifics. First you will need a full chemical analysis of the inksets and media which the piece was printed upon. Then you will also need a full spectral analysis of the lighting in the area where the piece is to be displayed. They will need the lighting frequencies as well as duration of exposure on an annual basis. Once you have that you can send the specific information to a lab to determine the difference in the 2 types of glazing. They might just choose to pay the small upgrade fee to the better glazing since it will be only a small fraction of the cost of the data accumulation and analysis.
 
You could always frame the piece, put it in a dark closet and never take it out.
 
Rob, I believe that filtering is in the 200-350 with some in the 350-450 range. ONLY.

Terry can tell you exactly, seeing how she did all the research for F.A.C.T.S..
 
The Tru-Vue catalog provides the latest information here:
http://www.tru-vue.com/files/TruVueCatalog.pdf

Tru-Vue's blocking is in the ultraviolet range of light, 300 to 380 nanometers. The goal is to eliminate as much light as possible in that frequency range, because it is the most harmful to items commonly framed. Current technology enables blocking about 99% of this frequency range.

The visible range is 400 to 700 nm, where frequency-blocking would directly affect the view. So, the goal is to transmit as much light as possible in that fequency range, in order to provide the best view through the glazing. This range is less harmful than UV, but still damaging, which is why all light exposure is harmful. Ordinary glass transmits about 91% of this frequency range, but current coating technology enables transmitting about 97% of it (soon to be about 99%).

The infra-red range is 700 to 1500 nm, but most of that light is blocked by the atmosphere and the glazing itself.
 
% in UV protection is only for price matter. There is no practical difference for different %, even in museum. Protect it from front 100% against UV, but how the rear side, top side,...
Every glass is UV barier more or less. Walls are also. Inside average home I can say there is no UV rays, unlike outside at direct exposure to the sun.
Poster value is next to ZERO, and to ask for protection that will push its lightfastness is just funny.

To answer your question:
0% UV protection (no any glass), work is inside house not at direct sun, art will last, say 20 years
100% UV protection, art will last around 25 years (in the best case).
I am oil painter too, and know it very well.

UV rays are only a small part of complex fading problem.
Can you find an old photograph old 80 years and never protected...
 
Jeanette

I find your post very interesting!

You back very little of your claims. It would seem that little is known of you on the grumbler, at least you reveal very little about yourself in your name, signature, and profile.

While your opinion is as acceptable on this forum as anyone else's, I am certain that we would all benefit more if you clearly revealed more about yourself AND gave some more detail about your experiences with UV filtration.

I hope you will.
 
I do have a sample I can show my clients of actual (non controlled) real life fading.

Years back, a client brought in a small needlework to be re-framed.

I photographed & printed a copy of the needlework, placed it with the faded matting.

I can peel the mat back to show how much the mattes & the needlework faded - it amazing.

The Client said it was on an inner wall for around 15 years. It had regular glass on it!!!
 
HB
Is it a photograph or digital print? There are a lot of differences between that two...
About fading: how sure you are it is due to UV? Are anythin else similar to that print, inside the house, faded the similar way?
(paper itself cause a lot of fading on digital prints...)
 
The Photo isn't fading - its the original ndlwrk was faded that I took a photo of!
 
As mentioned before we have no idea what caused the fading you found. It could have been uv or not. Filtered glass may have slowed that or not. We just don't know. That's the very kind of question that many seek answers.
 
Well it's too bad that poster I mentioned isn't online as it shows the difference in fading btw. UV filtered and unfiltered for known media and known amounts of light. For some things the filtering makes a difference, for some things not.

Maybe I'll see how much it would cost to have it scanned.
 
I always tell my customers that UV filtering is essentially ineffective in all but a handful of situations.

This is because most of the time somebody asks me about it, they want me to give my blessing to displaying a piece of artwork in a place that receives either very bright sunlight or even direct sun rays for some portion of the day. Almost everybody who asks this question assumes that UV filtering allows direct sun exposure without damage, seriously.

If they won't relent, I tell them that the visible blue component of light is almost as damaging as UV, and the solution to that problem is a deep yellow tint to the glazing. So move the stupid thing out of the sun, please. Also, I tell them that life expectancy for artwork exposed to direct sun rays is less than one year. And that even if light caused no damage at all, the solar heating would still ruin the piece very quickly through mechanical distortion.

Also, since I often deliver my large frames in person I frequently see horribly faded framed prints on the sunny living room walls of people who still believe in the myth UV protection in bright sunlight. Maybe the art faded so slowly the owners didn't notice.

Also, the difference between 70% filtering and 98% filtering is actually 15:1 or (100-70 / 100 - 98). So if 70% were somehow construed to "protect" for one year, then 98% could be construed to "protect" for 15 years, which is longer than the effective life expectancy for the UV protective agents in or on the glass.
 
more_so said:
.... then 98% could be construed to "protect" for 15 years, which is longer than the effective life expectancy for the UV protective agents in or on the glass.
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Hmmm I thought that I'd read on here MANY times that the UV filtering components do NOT degrade with time?
 
more_so said:
Also, the difference between 70% filtering and 98% filtering is actually 15:1 or (100-70 / 100 - 98). So if 70% were somehow construed to "protect" for one year, then 98% could be construed to "protect" for 15 years, which is longer than the effective life expectancy for the UV protective agents in or on the glass.
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I have never seen any evidence that the effectiveness of UV-filtering coatings on glass degrades over time. If you have any I'd be very interested in seeing it.
 
The UV filtering does not degrade. This has been discussed many times and I even believe the last time the link to TV's website was included. There is no loss of protection but I have a feeling some framers decided there was since they saw fading over time when they expected there to be none.
 
...could be construed to "protect" for 15 years, which is longer than the effective life expectancy for the UV protective agents in or on the glass.
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Perhaps this myth comes from the window-film industry, where the UV blocking capability actually will degrade due to its chemistry and due to intense light exposure over time. In most of those situations, the UV blocking film -- often tinted, as well -- is applied to a window in direct sunlight; the worst-case scenario.

The UV-blocking protection of glass and acrylic picture frame glazing will remain fully effective and will not degrade over time. For glass the coating is fused into the surface. For acrylic, UV blocking is in the formulation of the plastic sheet; it is not a coating.
 
Here's what happened

Well, here is the end of the story.

They picked the regular acrylic, although my recommendation was for UV filtering acrylic.

We spent a fair amount of time discussing the framing inside the frame, what I was using and why I was suggesting it's use. They agreed with everything except my recommendation for the UV filtering acrylic.

In spite of my best efforts, I couldn't convince them the answer they sought wasn't something anyone could give, there are just too many variables. In spite of explaining that UV filtering was protecting the paper, and the fading issue would still be there regardless, at least we were doing the best we can do to protect the paper and those colors damaged by UV. In spite of the "suggested framing techniques" the company who sells the posters puts with each poster - which recommends UV acrylic.

Their reason was "well, we aren't hanging it where it will get direct sunlight so there is no need for the UV filtering" - a phrase that nearly every customer in my store utters when we talk about UV filtering glazing. Probably that idea comes from "sunscreen for your art" which implies that it is made for use in brightly lit, sun filled areas and not needed in "other" situations.

It was as if they didn't hear one word I said.

Oh, well, can't win them all!

Thanks so much again for all of your suggestions and ideas. Much appreciated and very helpful!
 
more_so said:
I always tell my customers that UV filtering is essentially ineffective in all but a handful of situations.

This is because most of the time somebody asks me about it, they want me to give my blessing to displaying a piece of artwork in a place that receives either very bright sunlight or even direct sun rays for some portion of the day. Almost everybody who asks this question assumes that UV filtering allows direct sun exposure without damage, seriously.

If they won't relent, I tell them that the visible blue component of light is almost as damaging as UV, and the solution to that problem is a deep yellow tint to the glazing. So move the stupid thing out of the sun, please. Also, I tell them that life expectancy for artwork exposed to direct sun rays is less than one year. And that even if light caused no damage at all, the solar heating would still ruin the piece very quickly through mechanical distortion.

Also, since I often deliver my large frames in person I frequently see horribly faded framed prints on the sunny living room walls of people who still believe in the myth UV protection in bright sunlight. Maybe the art faded so slowly the owners didn't notice.
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This part of your post was dead on perfect. I agree 100%

Terry Scidmore CPF said:
Their reason was "well, we aren't hanging it where it will get direct sunlight so there is no need for the UV filtering" - a phrase that nearly every customer in my store utters when we talk about UV filtering glazing.

It was as if they didn't hear one word I said.
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I've heard it 1,000,000 times. I never, ever sell UV glass to protect art from direct sunlight. It will fade almost at the same rate as regular glass in direct sunlight. You have to be honest with your clients about what they should expect.

UV glass is not a magic bullet but a tool that needs to be use correctly.

framer
 
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