Question OK to alter original dustcover on glazed antique painting?

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aangles

aangles

CGF, Certified Grumble Framer
Joined
Feb 7, 2007
Posts
178
Loc
Wichita, KS
I have been brought an antique, original "Th. Van Sluys" (Theo?) painting on canvas of a group of sheep, apparently commissioned by a NYC art-dealing firm, Fishel, Adler and Schwartz, at who knows what date (guessing at least late 1800s, early 1900s). The painting is signed in curly cursive handwriting (with a flourish) on the back of the canvas itself by the artist, and includes a declaration of authenticity that it is his work and that it was commissioned by said firm (appears to be crow quill or fountain pen writing), which firm has a shop label still affixed to the dustcover. It is in an extremely ornate, heavy gilded frame (about 5" wide, comprised of three stacked sections, all gilded) and it is, ahem, glazed, with glass. It appears that the painting has never been taken out of the frame as the very brittle, friable dustcover is intact around the painting in various places, with the store's label intact. The artist's handwritten statement makes direct reference by name to the shop partners on the label. commissioning the work, guaranteeing that it is his own. The canvas itself is a brownish linen type on the back.

The main problem is that the glass has some efflorescence (?) on the inside of it that I strongly suspect is mold (a very faint bluish-grey bloom, almost indiscernible except when tilted at an angle), or quite possibly outgassing of the paint from the canvas. Or both.

The question I have is this. Given that it is presumably a relative rarity to have a piece this age with an intact dustcover over the surrounding frame and stretcher bars (with back of canvas left exposed), and the commissioning party's label on it, and the artist's attestation to that effect in handwriting and signed, is it going to decrease its value to take the painting out of the frame (ie to cut the dustcover at the point between painting stretcher bars and frame)to clean the inside of the glass and reassemble it? The painting is in excellent condition, as is the frame, but of course the dustcover (seriously fitted to each "step" on the back of the frame) is alarmingly friable, and when the customer originally brought it in, she was planning to take the painting out of the frame and put an antique portrait of her great-grandmother into it. But upon inspecting the piece more closely front and back and discovering it was a detailed original oil painting of seemingly very fine quality and also apparently in its original framed state, I have been hesitant to alter anything at all, even to the point of holding off replacing the loose wire hanger with a needed sturdier one regardless of whether it is opened up to clean the glass. I would probably not plan on cleaning the painting itself since it looks brand new (and indeed thought it was a print at first glance...). But afraid to do anything beyond cleaning the outside of the glass and a minor repair to the frame ornamentation.

So at this point I have been wavering between the necessity of cleaning that glass on the inside (if indeed it is mold) to protect the painting, or leaving the entire package as unchanged as possible. Always the dilemma of conservation needed vs. keeping it original. But I did manage to convince the customer that that painting should really be kept as it was as much as possible and while I am no art appraiser, feel that doing so should help preserve its value (it was part of an inheritance collection that included another very large Wm. Keith painting in an original frame also...also here...with glass on it...). But not crazy about leaving mold in the vicinity of the paint...and not sure of the parties of thought about altering the original dustcover. And also relatively clueless as to the monetary value of the painting and frame overall (as is the customer. hah.)

Any advice, opinions, or expertise on such a situation would be greatly appreciated. Of course we can always send it to a conservator, but I am sure there are some framing gurus out there who have been in the business longer than my own 20 years who might be willing to share their mindset on this... Anyone who would like to see a picture, I can take and post once I figure out how. LOL. I ought to be at about 6K posts after being a Grumble member for 4 years, lol...just get sidetracked by business...heck I gotta watch out, or between Grumble and Facebook I will NEVER get any framing done...:p
 
I would think if this painting were in my shop I would probably save all of the info and stickers and such on the original dustcover and open up that puppy to clean the inside of the glass.

Then reassemble the whole package with Lineco or Tyvek on the back and an envelope containing all of the original materials scavenged from the original backing plus a good photo of what the whole thing looked like before anything was done to it. Conservators document every step of their procedure, in writing and with photos.

Sounds like a good advertisement for glazing oil paintings, doesn't it?
 
If it's original, it has some value. I would not be quick to alter the dustcover without having your customer speak with an appraiser.
 
I believe that the Antiques Roadshow experts are available online to answer questions. Might be a good avenue art least in the beginning.
 
Hi,

If the glass has mold on the inside, canvas may have it as well. We have restored many dust covers, but would not put them back.
 
I think your estimate of age is about right. Here's some info I found on the artist concerning one of his paintings. All the provence info matches what you said is on the back of the art.

Theo van Sluys
Belgian, 1849-1931
SHEEP IN STABLE
Signed Th. van Sluys (ur) and inscribed on the reverse I declare that this painting/has been painted by myself to/the order of M...s. Fischel Adler &/Schwartz/Th. Van Sluys
Oil on canvas
23 5/8 x 31 5/8 inches (59.9 x 80.3 cm)
Provenance:
Fischel-Adler & Schwartz, New York
Collection of G.E Moredock, Jr., Barrington, Illinois

The work that this info was taken from was given an estimated auction value of $10k-$15k.
 
aangles said:
The painting is signed in curly cursive handwriting (with a flourish) on the back of the canvas itself by the artist, and includes a declaration of authenticity that it is his work and that it was commissioned by said firm...

...it is presumably a relative rarity to have a piece this age with an intact dustcover over the surrounding frame and stretcher bars (with back of canvas left exposed)...
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Whatever you end up doing about the paper on the back, you should give serious thought to using acrylic behind the canvas as a rigid backing when refitting.

You've seen the benefits of glazing a painting, and a backing behind it will provide protection from physical damage such as dents and punctures, excessive flexing of the canvas and soiling. Acrylic will do a great job and still allow the signature and notes on the back to be seen. Finish it off with frame sealing tape around the edges to close it off well and give it a finished appearance.
 
Photograph the back, preserve the dustcover fully intact if possible. If not possible, then, as Mar said, preserve as much as possible.

I don't think any appraiser is going to consider the existing package with mold
growing in it to be more valuable leaving as is and letting the painting self destruct over more time than if it was opened up and treated by a conservator if necessary. Preservation of the painting is more important the the dustcover itself.
 
Dave said:
Photograph the back, preserve the dustcover fully intact if possible. If not possible, then, as Mar said, preserve as much as possible.

I don't think any appraiser is going to consider the existing package with mold
growing in it to be more valuable leaving as is and letting the painting self destruct over more time than if it was opened up and treated by a conservator if necessary. Preservation of the painting is more important the the dustcover itself.
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I'll confess that I don't understand your logic here at all. You're talking about an artist whose work regularly sells for high four figure to mid-five figure prices at auction, in a market that is totally obsessed with original condition. This is a piece that is oddly framed (glass on an oil painting from 1900?), and yet there is some kind of hurry to permanently alter it without talking to an appraiser to verify it's providence and place a value on it, and without then talking to a conservator to determine the appropriate treatment?

It all seems so hasty, and represents a risk I would not be quick to take with a piece that could have value.
 
Dave said:
the existing package with mold
growing in it
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Visible presence of mold- should be #1 concern and would require professional treatment. Front and back of the painting needs to be examined and not just with naked eye. Dust covers with stamps, handwriting are preserved as a record. It all depends what your customer is willing to do at this point.
 
Now I see why they call it the Grumble, grrr. Just spent a bit too much time replying to this wealth of feedback (THANKS ALL), clicked Preview Post, and was prompted to log in again; then got a freaking blank page and my entire response, gone, I guess...I should know enough to copy something like this before hitting ANY button....

OK here goes again. First off, thanks for the comments and insights. I have run the gamut of all of these inclinations since this piece was brought to me. My gut instinct is to research the matter further with an appraiser or conservator, given its potential value, before doing anything.

diy and JBW9, thanks for the auction references. This painting is very much the same as that description, down to the inscription and the size and the subject matter, and in my own research I did gather that Theo Van Sluys aka Eugene Remy Maes, was fond of painting sheep...that auction estimate raised a brow but not really, given my customer's grandparents were apparently serious collectors, since she also brought in a similarly glass-glazed framed William Keith painting, whom I understand is a museum-grade artist. Researching that one next.

mbboston, definitely agree it is up to the customer at this point how far she wants to take this. I think that she'll be willing to get the opinion of a conservator given its potential value. I agree, if indeed there IS mold inside, it is likely on the painting as well, and should be checked out.

One of the other Van Sluys images on the Arcadja link mentioned varnish that had oxidized; would any of you happen to know what that looks like? The image showed some areas with a bluish cast and there are a couple areas in this painting with a bluish cast of what I was guessing might be mold and now wondering if it is merely oxidized varnish. Kinda like the water spots you get on laquered/varnished surfaces. What I am seeing on the inside of the glass, though, is more very faint foxing, but looks virtually colorless; you have to view the glass at an angle to see it.

One thing I am curious to get opinions on in regards to the issue of mold is the possible use of a thymol chamber to kill the mold spores; have any of you heard of doing this, and is this an accepted conservation practice? I have a large, handmade thymol chamber that I inherited with the equipment and fixtures I bought from a former longtime frame shop owner who had retired; he was at his peak in the late 70's and 80's. But I have always been rather unsure of whether this would do more harm than good, and certainly not inclined to do it to this painting without further advisement. Thymol is nasty, gloves-only-hold-your-breath toxic stuff, besides. :vomit:

Framar and diy, I, too, was totally surprised to see a glass-glazed painting from the 1900's... definitely something of an oddity. Does present a historical test of sorts for the pros and cons of glazing paintings; the painting is in great shape (with some craquelure as to be expected) and it was done with a spacer (unfortunately likely wood, though). I do like FramerDave's suggestion of putting acrylic on the back for additional protection but worry it may have the effect of drawing more of that friable dustcover off the back of the canvas, as that is where it is disintegrating, where it covers the primed canvas on the back. The label is actually on the duscover on the back of the canvas stretcher bars, too.

I laughed at Framar's Antiques Roadshow suggestion, since I LOVE that show and was thinking just the other day this piece was a good candidate for it, lol, but do seriously agree that might be a good starting point to at least ask for an art expert's opinion. Thinking about contacting the conservator at the Wichita Art Museum as well.

But overall feel like there has to be a balance between maintaining as much of the original frame job as possible (and saving every shred if it IS altered along with photo documentation) and preserving the painting by protecting it from potentially harmful elements. The frame too, is quite impressive, and the ornamentation is more or less intact despite the expected hairline cracks.

Thanks all for the comments; serves to bolster my gut feeling that this needs further research before tackling any basic conservation steps.
 
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I think it would be a good idea for a painting conservator to evaluate the condition of the painting once it is removed from the frame. He/She would be able to tell if the canvas needs to be re-backed in order to extend its longevity. Also, the stretcher that it is on may need to be replaced, since it has probably deteriorated over time, and must be leaching acid into the canvas, weakening it. The piece may look okay from the outside, but self-destructing gradually.

I agree with other respondents that the painting must be preserved over and above preserving the original backing, etc., and to take photos of it as is. The photos can be part of the provenance of the painting and travel with it for life, and perhaps the dust cover could be put into an acid - free clear envelope.
 
Here at ICA-Art Conservation, we regularly remove old dust covers. The as-is back is photographed as part of the before treatment process, the cover (or fragments thereof ) removed, any labels or inscriptions cut out and encapsulated, then these are taped (3M 415) to the new backing board. This is pretty standard procedure.
 
Thank you, 05, for your sane and sensible reply, emphasizing the importance of preserving the art itself along with any accompanying information regarding its origin, condition, and provenance, as opposed to the specific deteriorated backing materials that are not part of the work itself. I think sometimes we lose sight of the forest for the trees when we obsess about originality.
:kaffeetrinker_2: Rick
 
Exactly.
 
What 05 and Rick said.

Seriously, it's a dust-cover!

We keep and then re attach any labels that may be on the back of any dust-cover.
 
Thanks 05; YES! YES! Exactly the type of expert I was hoping to hear from (no offense to anyone else here, I respect ALL of your opinions!). That was my suspicion all along: ok to remove dustcover, preservation takes priority, and keep all original labels, which is what I do on anything as a rule. Of course it IS only a dustcover, albeit a very old one...

Thanks everyone for your input and suggestions!
 
I'm surprised nobody has mentioned this yet, but if you put that painting back behind the original glass, you are putting the painting at risk. If the glass breaks, the jagged shards could scratch or tear the painting. If you want to keep it safe behind glazing, swap out the glass for Optium Museum acrylic. It may cost the customer a few hundred dollars, but it will be shatter-resistant and virtually invisible. If the painting is indeed worth $10000 to $15000, it's a minor expense that will add a lot of value.
 
I for one am not a fan of glazing any kind of painting...and was pretty surprised to see this one done this way. Thought it was a fluke and an oddity until I examined the back and saw the evidence of its age and provenance, and that it was an original old oil painting and not the print it appeared to be at first glance, lol...it DOES have a gilded wood spacer between the painting and the glass and of course the glass is charmingly rippley. But the Optium Acrylic may not be a bad idea, IF she wants to spring for it....I would just worry that when you unglaze a painting that has been glazed for 100+ years, you are exposing the paint surface to pollutants and extremes in temp and humidity that it has never seen and you might see adverse effects and hastened deterioration in the paint. But that is just a gut feeling. Kinda like raising an old ship from the bottom of the ocean and letting it dry out too quickly....ie moving it from a stable environment to a more unstable environment.
 
This is an interesting and somewhat entertaining thread.
 
aangles said:
I for one am not a fan of glazing any kind of painting...
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Even now, after you have seen the benefit of glazing paintings first-hand, and learned in the other threads how glazing protects a painting, you would hesitate to glaze?

...I would just worry that when you unglaze a painting that has been glazed for 100+ years, you are exposing the paint surface to pollutants and extremes in temp and humidity that it has never seen and you might see adverse effects and hastened deterioration in the paint.
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You are correct to conclude that those hazards would harm a painting, but they probably would not harm this painting more than they would harm any other painting.

Maybe the old painting in pristine condition would have a slight advantage n resisting environmental deterioration, since its paint layers are fully cured. A "fresh" oil painting, framed unvarnished as so many of them are, might suffer far worse damage if exposed to an uncontrolled environment and contaminants during the whole time its layers are curing.

...Kinda like raising an old ship from the bottom of the ocean and letting it dry out too quickly....ie moving it from a stable environment to a more unstable environment.
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Consider how the stable underwater environment can preserve a ship for centuries. Now consider how long the same ship might have lasted if it had been exposed to the unstable environment of open air. Yes, without routine maintenance and repairs, it would have perished in only a few decades.

You have made a strong case in favor of glazing paintings. Thank you.
 
And just how sealed up do you think that frame ever was? The glass was no doubt a little smaller than the window, the painting itself probably held in with a few nails, and the a dust cover of paper. Hardly the anoxic environment of that underwater ship -an analogy that doesn't work anyway. Some protection was provided by the glass, sure, but not as much as you seem to believe.
 
05 said:
And just how sealed up do you think that frame ever was? ... Some protection was provided by the glass, sure, but not as much as you seem to believe.
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I don't believe it was "sealed" at all, but closure of a typical frame with glazing and a solid backing would protect it from the harm that comes with full exposure to open air. In addition to particulate soiling, it would be protected from accidental mechanical damage, insects, vibration from ambient sounds, and most airborne chemical contaminants (exhaust, oils, etc.).

For retail framers, as most of us here are, I would not suggest completely sealing the frame, because ordinary framing with glazing and a solid backing would provide most of the protective benefit.

Complete sealing - never mind an anoxic environment - would require conditioning all of the hygroscopic materials and require routine maintenance. For the few of us out here in the real world that might have the expertise and equipment to do it properly, complete sealing and its maintenance would add significantly to the cost, and it might give the owner a false sense of security.

Closing a canvas painting's frame with glazing and a solid backer is well within the expertise of most retail framers and it is not terribly expensive, but it protects the painting from most hazards.

And to address the original issue, I'd put the old dustcover in an envelope of Mylar/Melinex and attach that to the new dustcover, or give it to the owner separately.
 
Ha, yes, I do have to agree that this painting is far from "sealed up" per se, and I will concede that the ship underwater analogy is also probably way overboard. (haha, no pun intended.) I have always rather felt, too, that the exposed back on a glazed painting with an open back dustcover allows ventilation and all its concomitant exposure to pollutants and environmental fluctuations to that side anyway so that any glazing on the front is likely not all that much of a deterrent to those elements on the back anyway. But as Jim says, it DOES protect from a number of issues as does any frame package with glazing in it, and I believe it will also reduce the extremes of fluctuation in temperature and humidity somewhat too. There are so many chemical and mechanical elements at work in causing deterioration both with and without glazing that it is virtually impossible to ELIMINATE all of them in any particular method but they can certainly be reduced by several; the goal is to achieve maximum stability but absolute stability is impossible.

What about the possibility that glazing paintings is not recommended simply because of the volatile nature of the solvents in the paint? Is there ever any argument for spontaneous combustion? Granted, if the painting is thoroughly dry before glazing there would presumably be very little solvent present but did wonder about that aspect of it and am not all that knowledgeable about oil paintings and the curing process in general myself, other than what all of you have shared herein...now I suppose that i have never seen an oil painting spontaneously combust but...

@Dave, glad you find this thread entertaining. Me too, and educational. There is something to be said for ALL of these comments. Just to help you all see what I am dealing with, going to try to get some of the promised images posted...give me a minute since i haven't posted pics to this forum before. Can't be too hard. heh.
 
IMG_5766 (800x600).jpgIMG_5765 (800x600).jpgIMG_5753 (800x600).jpgIMG_5757 (800x600).jpgIMG_5760 (800x600).jpg

Ok, i could only attach 5 of the 6 pics but these are representative. There is an overall image of the painting, one of Van Thuys' signature on the back, one of the dealers' label, and two closeups of the painting itself through the glass. The one with the chickens shows a bluish tinge covering the black chicken; I had thought this was mold but now wonder if it is oxidized varnish. In the same image upper left corner area you can see some tiny whitish spots; these are on the inside of the glass and reasonably sure they are mold of some variety. I tried to take that shot from an angle and light where they would show up best; they are very faint and not obvious at casual observation.

The detail with the hoof on the left also shows more of the same bluish streaking in the varnish as the black chicken.

I have a shot of dustcover detail that did not upload so will try that next post.
 
IMG_5758.jpg

Here is a shot of the upper left corner of the dustcover. As you can see, the paper covers all three frame sections and the canvas as well. Since it is extremely brittle and friable (as evidenced by the breakage where it is creased) it might be a little difficult to remove in any whole sections to salvage, but certainly could try and save as unaltered as possible. More likely it is going to fall apart...
 
aangles said:
The one with the chickens shows a bluish tinge covering the black chicken; I had thought this was mold but now wonder if it is oxidized varnish.
The detail with the hoof on the left also shows more of the same bluish streaking in the varnish as the black chicken.
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It's hard to tell without a much closer view, but there's a good chance that what you see is blooming. It's a sort of a milky appearance to the varnish layer which is caused by applying the varnish during overly humid conditions. It appears blue because it's over an area of dark paint. I'd wager that it's present elsewhere, just more obvious in the dark areas.

And no, it has nothing to do with having been glazed.

Also I'm not a painting conservator, just applying Occam's razor.

aangles said:
But as Jim says, it DOES protect from a number of issues as does any frame package with glazing in it, and I believe it will also reduce the extremes of fluctuation in temperature and humidity somewhat too. There are so many chemical and mechanical elements at work in causing deterioration both with and without glazing that it is virtually impossible to ELIMINATE all of them in any particular method but they can certainly be reduced by several; the goal is to achieve maximum stability but absolute stability is impossible.
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And yes, Jim is correct. And it's not just one person's opinion, Jim's opinion is shared by many conservators and organizations whose job it is to preserve some incredibly valuable artwork. And that list includes our own Hugh Phibbs, of the National Gallery of Art.

And no, there is no 100% absolute stability, but the use of glazing and a rigid backing goes a long way and it's something well within the skill level of most any framer.


aangles said:
What about the possibility that glazing paintings is not recommended simply because of the volatile nature of the solvents in the paint?
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To paraphrase the late great Bette Davis: But it is Blanche, it is recommended!

aangles said:
Is there ever any argument for spontaneous combustion? Granted, if the painting is thoroughly dry before glazing there would presumably be very little solvent present but did wonder about that aspect of it and am not all that knowledgeable about oil paintings and the curing process in general myself, other than what all of you have shared herein...now I suppose that i have never seen an oil painting spontaneously combust but...
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I seriously doubt that we have to worry about paintings exploding in flames. But in all seriousness, the solvents evaporate fairly quickly, generally within a matter of days or weeks at the most.

The curing (not drying!) process takes a lot longer, and I have seen it written that an oil can take as long as 80 years to fully cure. But this curing process is a chemical one, with the oils and pigment cross linking and forming longer molecular chains. This process is NOT dependant on airflow, and I would bet a longer curing process would produce a stronger paint layer.

Again, putting glazing on a canvas* will not harm it, and the worst that can happen is that natural offgassing from a too-fresh canvas will dirty the glass. This can be cleaned, and will not affect the artwork.









*With the usual caveat of a proper separation between the glazing and the artwork. Otherwise all bets are off.
 
I don't know about you folks, but I'd love to see a painting erupt in spontaneous combustion. When I was a kid, I was fascinated by stories of people who had burst into flames from spontaneous combustion. This was before people smoked crack, mind you.
 
I have heard of bloom as well so might be the case. I think that is the term I have been searching for. I had just seen a reference to the presence of oxidized varnish under a description of condition for a similar Van Thuys painting listed in an auction catalog in a link given earlier in this thread, and noticed its similarity to this one. Might be referring to the same thing. More research is in order but this sure doesn't look that much like mold, especially because it seems to follow the brushstrokes of the varnish. On the other hand the "bloom" on the inside of the glass sure does look like mold...

And btw, what's applying Occam's razor....? I have an idea...

After 20 years of recommending not to glaze paintings and proceeding to do so on a few anyway, with the proper spacers, looks like I may need to change up my mantra and offer my customers a choice from here on out, since there ARE benefits to glazing. Did notice on a recent visit to the Nelson-Atkins in KC that some of their valuable paintings on display (Monets??) had museum glass-like glazing on them...but not all of them by any means. The ones that were glazed appeared rather fragile in condition, and I am reasonably confident that they are glazed BECAUSE they are fragile and not fragile because they are glazed.

Plenty of food for thought and yes, knew this would eventually turn into yet another discussion of glazing vs not. I really had no intention of taking the glass OFF of this painting since it was originally framed that way, and if it is as protective and harmless as a number of you advocate I am even more so inclined to leave it. But the issue of microorganisms possibly attacking the paint layer is much more grave and so needed to ensure that there is little decrease in value to alter the painting's reverse side (while saving everything and photographing all) to permit necessary conservation measures.

And no, I am not a painting conservator, either, but do have enough knowledge from past museum conservation training to know that it appears to have issues that need to be addressed by someone more knowledgeable in the subject...

So no one has heard of using a thymol fumigation chamber to kill mold spores? I mentioned it earlier but got no comments on that. Perhaps a new thread would be in order here, heh.

Thanks for all the feedback on this; you are going to see a lot more of me out here now! Now to learn to shorten my posts...
 
PaulSF said:
I don't know about you folks, but I'd love to see a painting erupt in spontaneous combustion. When I was a kid, I was fascinated by stories of people who had burst into flames from spontaneous combustion. This was before people smoked crack, mind you.
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LOL, it sure seems like a logical assumption doesn't it? I mean, after all, what's an oil painting but an oily rag, and if it's in a little box... KABOOM!:D
 
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aangles said:
And btw, what's applying Occam's razor....? I have an idea...
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Occam's razor is the law of parsimony. It boils down to: The simplest explanation, the one that calls for the fewest new assumptions, is generally going to be the correct one.

aangles said:
Did notice on a recent visit to the Nelson-Atkins in KC that some of their valuable paintings on display (Monets??) had museum glass-like glazing on them...but not all of them by any means. The ones that were glazed appeared rather fragile in condition, and I am reasonably confident that they are glazed BECAUSE they are fragile and not fragile because they are glazed.
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Probably a matter of time and money. They have to prioritize and allocate a budget, so the ones most in need of protection from further damage get glazing first. And what you likely saw was not Museum Glass, but Optium Acrylic. Same UV-filtering and anti-reflective properties as Museum glass with half the weight and twenty times the shatter resistance.


aangles said:
So no one has heard of using a thymol fumigation chamber to kill mold spores? I mentioned it earlier but got no comments on that. Perhaps a new thread would be in order here, heh.
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It used to be common practice, but it's generally no longer recommended. Don't recall exactly why, but I believe it was found to be damaging to paper. Probably not too good for canvas either.

As long as the canvas is dry and doesn't have any mold actively growing on it now, you'd probably be ok just cleaning the glass well and very very gently brushing off any dried mold from the painting with a very soft brush. Then refit and it would be ok as long as humidity and temperature don't get too high and create conditions that would lead to future mold growth.
 
FramerDave said:
Occam's razor is the law of parsimony. It boils down to: The simplest explanation, the one that calls for the fewest new assumptions, is generally going to be the correct one.



Probably a matter of time and money. They have to prioritize and allocate a budget, so the ones most in need of protection from further damage get glazing first. And what you likely saw was not Museum Glass, but Optium Acrylic. Same UV-filtering and anti-reflective properties as Museum glass with half the weight and twenty times the shatter resistance.




It used to be common practice, but it's generally no longer recommended. Don't recall exactly why, but I believe it was found to be damaging to paper. Probably not too good for canvas either.

As long as the canvas is dry and doesn't have any mold actively growing on it now, you'd probably be ok just cleaning the glass well and very very gently brushing off any dried mold from the painting with a very soft brush. Then refit and it would be ok as long as humidity and temperature don't get too high and create conditions that would lead to future mold growth.
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(I can't figure out how to multi-quote yet other than clicking the icon, so bluh, gonna hafta say it all in one place...)

Re museum glazing-Yes, that would certainly make sense; they were pretty good-size paintings that were glazed. With my background in museum work I am certainly familiar with prioritizing and budgeting according to most urgent need...they never have enough to go around.

Re thymol- Always wondered if it might have a detrimental effect on things given its highly toxic properties...gonna have to research that some more.

Re suggestion for cleaning-- this was actually my gut instinct on how to handle this piece from the get-go; my client will still need to decide if she wants to consult a conservator or appraiser on the dustcover issue, but I felt that it would be fine to just clean the glass and gently dust the painting off, once I looked into whether it accepted practice to remove an old original dustcover without jeopardizing the painting's value.
 
aangles said:
I have always rather felt, too, that the exposed back on a glazed painting with an open back dustcover allows ventilation and all its concomitant exposure to pollutants and environmental fluctuations to that side anyway so that any glazing on the front is likely not all that much of a deterrent to those elements on the back anyway.
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The benefit of glazing depends on complete closure of the frame. If the painting has glazing on the front and an open back, most of the benefit would be lost. There would be much less slowing of temperature & humidity changes inside the frame; less slowing of expansion/contraction cycles. There would be almost no deterrent to airborn contaminants, particulate soiling, or insects. There would be no deterrent to flexing/vibrations from sounds.

Closing the back with a solid board has been recommended for many years, and the "canvas has to breathe" myth has been debunked since at least 1965, when Caroline Keck published the ventilation hazards in her book.

Your photo of the dustcover shows the keys and the back of the canvas, so apparently this painting spent at least some time open on the back, right?

There are so many chemical and mechanical elements at work in causing deterioration both with and without glazing...
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Please explain how glazing causes deterioration. So far, I have learned only of glazing's benefits.

What about the possibility that glazing paintings is not recommended simply because of the volatile nature of the solvents in the paint?
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As David noted, glazing canvas paintings is recommended. In the past I have invited others to cite conservation authorities who recommend against glazing paintings, but so far, the only excuse (vs reason) for not glazing is aesthetic: "I want nothing between my eye and the paint". Do you know of any technical reasons not to glaze? If so, please share.

As far as the paint is concerned, I doubt that combustible solvents could remain in the paint more than a few days in open air. Closing the painting into a glazed & solidly backed frame would serve to slow the curing process, which could only help to strengthen the paint layers. The only known consequence of glazing a wet painting is fogging of the glazing, as the curing paint may offgas. However, that is nothing more than a slight inconvenience. Open the frame, clean the glazing, and refit it. The deposited film does no harm to the glazing or its optical coating. Every painting I frame with glazing includes free cleaning/refitting as often as it may be needed. It is a non-issue.
 
Jim Miller said:
The benefit of glazing depends on complete closure of the frame. If the painting has glazing on the front and an open back, most of the benefit would be lost. There would be much less slowing of temperature & humidity changes inside the frame; less slowing of expansion/contraction cycles. There would be almost no deterrent to airborn contaminants, particulate soiling, or insects. There would be no deterrent to flexing/vibrations from sounds.
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That is exactly what I meant as far as glazing the front only of a painting; not going to provide much protection if the back has been left open.

Closing the back with a solid board has been recommended for many years, and the "canvas has to breathe" myth has been debunked since at least 1965, when Caroline Keck published the ventilation hazards in her book.
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Hmmm, I have been framing since 1990 and thought that the glazed, sealed painting trend was more recent. Guess the "canvas needs to breathe" mantra is a stubborn myth to dispel since I was never trained to do paintings on canvas any other way...for exactly that reason. I am familiar with Caroline Keck's writings from my days in grad school in the mid-80's doing museum studies and museum conservation coursework, but I must have missed this... but then my focus was ethnographic collections (anthro and historical) more so than paintings. All that long before I became a framer...museums had very few paying jobs back then...

Your photo of the dustcover shows the keys and the back of the canvas, so apparently this painting spent at least some time open on the back, right?
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Yes. This painting has apparently always had the back of the canvas open; the dustcover stops around the inner edge of the canvas stretcher and exposes the back of the canvas at that point. I needed to post an image of the entire back of the framed painting.

Please explain how glazing causes deterioration. So far, I have learned only of glazing's benefits.
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I have to say this is pure speculation on my part, rooted in logic, but I will concede I could be totally wrong about this. While this statement may not apply so much to oil on canvas, as you have pointed out, I would think that a sealed painting might be more susceptible, for example, to condensation that could trigger mold growth under the right conditions if it is sealed in humid conditions, or hung or stored in less than favorable conditions; witness this painting and the mold on the glass and quite likely on the painting as well (although this one is not really "sealed" per se).

But more generally speaking, when you encapsulate or seal an item that outgasses or that has chemically reactive or acidic components in its makeup (inherent vice), those vapors that occur as the item responds to environmental fluctuations and aging processes can actually harm the artwork just because they are kept at a higher concentration in close proximity to it. Examples are good old lignin in inferior wood pulp papers and matboards, sulfur in wool items, acetic acid from oak, and other organic materials. Anything that is offgassing or outgassing to the point that it shows up on the glazing would be depositing those same byproducts on the artwork itself. I don't know enough about the chemical makeup of outgassing and other byproducts of aging and curing paint and so forth to be able to state with any degree of certainty that they are harmful; I am merely stating that the possibility exists. So my statement that glazing can contribute to deterioration was really intended more as a generalization might occur for SOME items of questionable composition and not necessarily just on oil paintings specifically.


Do you know of any technical reasons not to glaze? If so, please share.
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More or less answered above; again I am not a conservator and only had rudimentary training in the basic properties of organic and inorganic materials and their response to environmental factors (light, temperature, humidity, and chemical) but while I am for the most part an advocate of glazing all framed items since its benefits far outweigh the possible risks, it bears consideration on a case-by-case basis. Sure it is easy to clean the glass when outgassing clouds it but what is going on at the molecular level on the surface of the artwork? Once again I would emphasize...this is highly speculative on my part. I do not profess to be an expert in the subject even though I am probably rambling like one. :nuts:

So don't get me wrong, I do advocate glazing on just about everything I frame (textiles and fabric art, ALWAYS), but really was unaware there was such a strong school of thought on glazing paintings and sealing their backs. I was aware of a recent trend toward back-sealing, but this is really the first time I have seen very strong sentiment in favor of both glazing and sealing. So thanks for some eye-opening comments, and a little more knowledge about the curing and aging process that paintings go through; guess current conservation education is never a bad idea. But since my area of focus in my own conservation studies was primarily ethnographic and historical collections, I still feel rather vague about the specific conservation issues related to paintings, and also as witnessed by the original question on the thread, about certain issues in regard to preserving original state vs. conservation needs, which is always going to be an issue with any antiquated item.
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When I was recently in England, we toured Windsor Castle. I could see the characteristic bluish haze on all the Queen's paintings, which are bigger names than any you or I will ever see (exception being Hugh). I figure if its good for the Queen's paintings, it probably is unlikely to hurt lesser ones. I should have thought to ask to see the backs.....
 
aangles said:
...While this statement may not apply so much to oil on canvas, as you have pointed out, I would think that a sealed painting might be more susceptible, for example, to condensation that could trigger mold growth under the right conditions if it is sealed in humid conditions...
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Yes, "sealed in humid conditions" would be an invitation to trouble. But as I tried to describe back in post 27, we are not talking about a "sealed" frame, which would stop any transfer of moisture and air. Complete sealing could be done, but that would require pre-conditioning all of the hygroscopic materials going into the frame package, and it probably is not practical in retail framing. Retail framers, lacking the expertise and equipment to seal the frame properly, might create precisely the harmful condition you decribed above.

Rather, we are talking about a tightly-closed frame, which can still acclimate to its environment, but much more slowly than it would if it were left open. Again, slowing the rate of change inside the frame is an important benefit.

...or hung or stored in less than favorable conditions...
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Yes, of course a hostile display environment would affect the frame. But if a painting were exposed to a hostile environment, it would fare better in a tightly closed frame with glazing and solid backing, than if it were only partially closed or left fully open.

...when you encapsulate or seal an item that outgasses or that has chemically reactive or acidic components in its makeup (inherent vice), those vapors that occur as the item responds to environmental fluctuations and aging processes can actually harm the artwork just because they are kept at a higher concentration in close proximity to it...
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There's nothing in the paint that could offgas and harm the paint.

...Examples are good old lignin in inferior wood pulp papers and matboards, sulfur in wool items, acetic acid from oak, and other organic materials. Anything that is offgassing or outgassing to the point that it shows up on the glazing would be depositing those same byproducts on the artwork itself.
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Those concerns certainly are applicable for paper documents, photos, fragile textiles, and other items that might be framed with chemically invasive frame elements or decorative features. That is why preservation framing knowledge dwells on component chemistry.

Yes, if a deposit of an unknown film turned up inside the glazing of a framed document or photo, we should rightly be concerned, because that offgassing probably emanated from some component of the frame, and not from the art itself.

Oils on canvas are usually framed simply, without those elements that could be damaging. The offgassing in this discussion comes from the paint itself, not from other sources.

...I don't know enough about the chemical makeup of outgassing and other byproducts of aging and curing paint and so forth to be able to state with any degree of certainty that they are harmful...
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I don't know enough, either, and certainly didn't decide on my own. I asked a few people who are knowledgeable. They all agree that:

(1) tightly-closed framing slows the rate of oil paint curing;
(2) slower curing of oil paint is a benefit, not a detriment;
(3) anything emanating from curing oil paint is not harmful to the paint;
(4) an accumulation of offgassed film would not harm any sort of glazing;
(5) offgassed film can be easily cleaned from any glazing
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Thanks, Jim, it is good to know these things about paintings with a degree of certainty since your contacts are more knowledgeable about the subject. Makes a lot of sense. I rather went beyond the scope of paintings in my comments to include other items with the feeling that if THOSE could be threatened by the microenvironment created by glazing, then it would seem logical that this might happen to paintings as well. I think moisture under the glass would be the greatest danger with glazing paintings, but as you have pointed out, unlikely in the case of a painting that is not sealed. At any rate, THIS painting is keeping its glass, at the very least. :)

Ellen, good to know that. haha. The Queen's paintings are certainly a haughty standard to gauge by! Would have certainly been interesting to see those backs!
 
aangles said:
I rather went beyond the scope of paintings in my comments to include other items with the feeling that if THOSE could be threatened by the microenvironment created by glazing, then it would seem logical that this might happen to paintings as well.
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I have not learned of any items, properly framed, that "could be threatened by the microenvironment created by glazing". As far as I know, the not-quite-sealed microenvironment we're discussing is always is a good thing.

I think moisture under the glass would be the greatest danger with glazing paintings, but as you have pointed out, unlikely in the case of a painting that is not sealed.
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"Moisture under the glass" is a matter of condensation caused by dew point, and we have discussed that before. Searching in the archives will provide several references.

Speaking of archives, here's a thread on this topic from 2006. Deja vu, eh?
 
Thanks, Jim!! Was looking for the link, haha.

I will certainly look those over. Do agree in principle that glazing is more protective in general than not and that the benefits usually outweigh the risks. And in 20 years of framing I have yet to see actual condensation in a frame, myself. Although possible that some pieces that exhibit past moisture damage may be suspect in that regard...I have however seen plenty of improperly framed photographs stuck to glass so guessing it may be more common than I think.

Now to pass all this info on to my client so she can make an informed decision... how come I can't copy a link to this thread specifically, but only have the PFM Grumble homepage link in my address bar? hmmmm. :shrug:
 
Oh, heh-heh, found the "email to a friend" button. Knew it had to be there. :confused:
 
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