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Author Topic: plexi vs. glass  (Read 6468 times)

Lero

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plexi vs. glass
« on: November 23, 2009, 05:42:48 pm »

Is it a problem to frame with plexi-glass rather than glass?
I need to ship a framed photograph and prefer to use plexi.
Will the plexi emit gases and cause the paper to yellow over time.
Framer says no, Hahnemuhle says maybe....
I am using photo rag bright white matt paper.
Thank you
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bill t.

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« Reply #1 on: November 23, 2009, 06:23:47 pm »

Well, if you ignore the problems associated with bis-birefractive archival-antogonistic cross-redigitization of the photonic-submatrix, then 1/8" plex works pretty good up to about 18x24, think about 3/16" inch above that and quarter inch for the real honkers.

Acrylite-FF works real good and it comes in at about $70 for a 4x8 foot sheet.  Most plastic suppliers will have it and for anywhere from $0 to $15 will cut it into as many smaller pieces as you like.  You can often find smaller pieces for free or very cheap in the trims bin.

If spending money is important, near-invisible Optima will protect your art for around $50+ per square foot.  Between there and Acylite-FF you have OP-3 or something like that with UV protection.  That's the range of possibilities.

Some galleries will no longer take glass for works above some rather small size...breaking glass on a dropped frame tears up both art and gallery visitors alike.

If you use plex, be sure to wipe down both sides with Novus 1 plastic cleaner before closing the frame, it kills static which would otherwise make you crazy.

Have never had outgassing or any other problems with plex, but then I used to let my RC and glossy papers dry quite a few days before framing.

When framing with plex, the biggest gotcha is fun-house mirror reflections from plex that is squeezed or warped by the frame.  Try very hard to have your plex a good 1/8" smaller on all sides than the frame.  Also, the lip surface that supports the plex should be in exactly the same plane on all four sides, with no little bubbles of glue raising one corner of the plex.  I have heard that the spring clips that hold the glazing and artwork in place in metal frames can distort plex it they are too close or too far, but have no experience with this and don't know what the best spacing is.
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neile

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« Reply #2 on: November 24, 2009, 01:02:12 am »

I am completely addicted to Acrylite OP-3 (TruVue anti-reflection conservation clear). That stuff is damn near invisible when framing images. I agree with Bill, you have to wipe it down really well with lint free cloths and Novus 1 Plexi Polish to ensure no static before framing, but once you're all done it's absolutely amazing.

I gave up long ago trying to score and snap it with a plexi blade, and now have a proper blade for my table saw that makes quick work of slicing it. Many plastic supply places will do it for you while you wait if you don't have the luxury of a saw around. One source if you are in the Northwest is http://www.tapplastics.com/

Neil
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Ernst Dinkla

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plexi vs. glass
« Reply #3 on: November 24, 2009, 02:56:58 am »

Quote from: Lero
Is it a problem to frame with plexi-glass rather than glass?
I need to ship a framed photograph and prefer to use plexi.
Will the plexi emit gases and cause the paper to yellow over time.
Framer says no, Hahnemuhle says maybe....
I am using photo rag bright white matt paper.
Thank you

Acrylic is very stable. You will not see gas emissions. It keeps its colorfree transparency in time too.


met vriendelijke groeten, Ernst Dinkla

Try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/
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Lero

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« Reply #4 on: November 24, 2009, 07:50:40 am »

Quote from: Ernst Dinkla
Acrylic is very stable. You will not see gas emissions. It keeps its colorfree transparency in time too.


met vriendelijke groeten, Ernst Dinkla

Try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/


Thank you. If I use print shield spray  can I use regular plexi rather than UV plexi?
In case there is ever yellowing I think regular plexi will allow UV rays in which would help reverse any yellowing.
That is my thought.
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Gary Ferguson

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« Reply #5 on: November 24, 2009, 08:46:18 am »

Quote from: bill t.
1/8" plex works pretty good up to about 18x24, think about 3/16" inch above that and quarter inch for the real honkers.

Wow, you build them to last in New Mexico! Here in Europe styrene sheet is more commonly used, but in 1.2mm thickness which is a shade less than 1/16". The only additional problem I've encountered is that the UV inhibitors in some plastics can yellow over time, I guess better they yellow than the artwork fades. I'd also second the point about ensuring a completely flat and plane ground for plastic sheet, it looks terrible if there's any twist at all.
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Ernst Dinkla

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« Reply #6 on: November 24, 2009, 09:11:20 am »

Quote from: Lero
Thank you. If I use print shield spray  can I use regular plexi rather than UV plexi?
In case there is ever yellowing I think regular plexi will allow UV rays in which would help reverse any yellowing.
That is my thought.


I do not understand the "reverse any yellowing effect". If you think about bleaching a yellowed paper by giving it a UV treatment I think you are on the wrong course. Paper becoming more yellow in time can be related to many causes: the (little) OBAs in the coating and/or paper losing their effect, any wood base in the paper showing its origins, staining by air or other materials in contact with the print.  UV light will not make that any better and the inkjet inks in the image will show the exposure to UV light by fading. If you burn the print carefully you may end with white ash but I don't think that is a good approach either.

Check the tests done by Wilhelm and Aardenburg. The tests methods  vary: with glass, without glass, etc.  All for indoor use. There are different print life estimations given per method. The usual approach is to frame behind glass and not add any coating on the paper. Papers preferably not having OBA content and made of cotton or alpha cellulose pulp that got extra calcium buffering against acids. Normal window glass already cuts UV at approx. 350 Nm. The same used for frames indoors will help but some purists state that more UV should be cut out for better protection.

I have seen a (in Dutch and not so recent) test page that qualified the UV protection of several UV blocking materials as inadequate. What was rated as good suggested to me that it would filter the print color too. Last week I had do a reprographic job on a 1920's photograph that was framed like that.  It needed a thorough red color removal to compensate for the UV blocking filter of the glass used.

Where Canvas prints are discussed the choice becomes a different one. They will not be framed behind glass and need a varnish coating for several reasons I can think off. Protection against mechanical impact to a degree, humidity control, gas fading, light fading, reduce staining by air pollution and make it possible to clean it professionaly whenever needed.



met vriendelijke groeten, Ernst Dinkla

Dinkla Gallery Canvas Wrap Actions for Photoshop
http://www.pigment-print.com/dinklacanvaswraps/index.html


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Lero

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« Reply #7 on: November 24, 2009, 09:47:22 am »

Quote from: Ernst Dinkla
I do not understand the "reverse any yellowing effect". If you think about bleaching a yellowed paper by giving it a UV treatment I think you are on the wrong course. Paper becoming more yellow in time can be related to many causes: the (little) OBAs in the coating and/or paper losing their effect, any wood base in the paper showing its origins, staining by air or other materials in contact with the print.  UV light will not make that any better and the inkjet inks in the image will show the exposure to UV light by fading. If you burn the print carefully you may end with white ash but I don't think that is a good approach either.

Check the tests done by Wilhelm and Aardenburg. The tests methods  vary: with glass, without glass, etc.  All for indoor use. There are different print life estimations given per method. The usual approach is to frame behind glass and not add any coating on the paper. Papers preferably not having OBA content and made of cotton or alpha cellulose pulp that got extra calcium buffering against acids. Normal window glass already cuts UV at approx. 350 Nm. The same used for frames indoors will help but some purists state that more UV should be cut out for better protection.

I have seen a (in Dutch and not so recent) test page that qualified the UV protection of several UV blocking materials as inadequate. What was rated as good suggested to me that it would filter the print color too. Last week I had do a reprographic job on a 1920's photograph that was framed like that.  It needed a thorough red color removal to compensate for the UV blocking filter of the glass used.

Where Canvas prints are discussed the choice becomes a different one. They will not be framed behind glass and need a varnish coating for several reasons I can think off. Protection against mechanical impact to a degree, humidity control, gas fading, light fading, reduce staining by air pollution and make it possible to clean it professionaly whenever needed.



met vriendelijke groeten, Ernst Dinkla

Dinkla Gallery Canvas Wrap Actions for Photoshop
http://www.pigment-print.com/dinklacanvaswraps/index.html

I think you are right re: wrong course using UV light for bleaching. It's just that I had two exhibitions in which I had mounted and framed the work without glass or plexi but I sprayed them with print shield which also gives UV protection. Within 24 hours of hanging the work there was a yellowing in the prints due to contaminants in the air. (room was painted a few days before in one case and small paint touch-up job in another-acrylic paint). Both times I carried the work into sunlight and that reversed the yellowing. We aired out the rooms better, re-hung the work and it was fine. So I thought- if ever there was yellowing by some mysterious unforseen force it could possibly be reversed if the plexi was not UV plexi.
Also I spoke with Hahnemuhle and the technician said the spray "finishes the job". That it helps the print somehow become more complete or more fixed into the paper. He recommended  the spray for every finished print.

My thought was to spray and then use a frame with plexi glass but not a UV plexi...just in case. I will look at the Wilhelm tests but I always have difficulty with the site especially with Hahnemuhle photo rag bright white matt paper. The PDF came up blank every time. Will try again.

Thank you.
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Alan Goldhammer

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« Reply #8 on: November 24, 2009, 09:54:14 am »

I didn't want to waste any more space by quoting Ernst's post above but do echo his thoughts.  In particular you should go to the Aardenburg site and look at some of the reports (you don't have to join but you only have a limited number of reports to view).  As I recall the tests done there are with normal plexi and not with UV blocking.  For normal viewing away from direct sunlight, pigment inks have great stability (the papers that I use were stable for greater than 50 years under the test conditions).  As with Ernst, I find it hard to understand how the print can yellow if it is on good quality stock.  One would also expect that conservation matboard would also yellow, something that I have never observed and I've had some silver gelatin prints on display for over twenty years with no apparent change in the matboard.  In fact, I took one out of the frame about a month ago and looked at the undermat which was shielded from display and one can directly compare that with the overmat.  There was not visible evidence of discolor.

I think the use of acrylic with the UV additives to be unnecessary both from a scientific and cost view.  Of course one should be careful not to hang anything where there is direct exposure to sunlight for pronlonged periods of time.
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TylerB

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« Reply #9 on: November 24, 2009, 12:50:21 pm »

I would encourage everyone to look into the activity at Aardenburg Imaging & Archives, in fact there is little excuse for members here to not be subscribers. I know Mark is aware of this problem because we discussed it. But I doubt he is in a position to research the reaction, define it, and repost to the rest of us specific results, for all kinds of reasons.
But, this continued confusion that the yellowing discussed here is in any way similar to the yellowing of paper we are used to. It's not the same at all, it's the coating, and it's reaction to certain evaporates and exposure to UV does indeed reverse it, Lero was correct.
Of course there are all kinds of other reasons to keep UV from your art.

A great deal of photographic output over the last several years may be vulnerable because this issue, and others related specifically to inkjet materials, continues to elude the community, even many experts.
Tyler
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MHMG

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« Reply #10 on: November 24, 2009, 02:43:47 pm »

Quote from: TylerB
I know Mark is aware of this problem because we discussed it. But I doubt he is in a position to research the reaction, define it, and repost to the rest of us specific results, for all kinds of reasons.
But, this continued confusion that the yellowing discussed here is in any way similar to the yellowing of paper we are used to. It's not the same at all, it's the coating, and it's reaction to certain evaporates and exposure to UV does indeed reverse it, Lero was correct.
Of course there are all kinds of other reasons to keep UV from your art.

A great deal of photographic output over the last several years may be vulnerable because this issue, and others related specifically to inkjet materials, continues to elude the community, even many experts.
Tyler

Hi everyone. Tyler, I'm also aware of the other thread on the yellow staining issue, but have been away from the office in the last few days, so I'm behind on entering these discussions. First, the yellow staining issue is a chemical reaction with some effluent from certain adhesives, and other possible sources of gaseous pollutants. I experienced this problem myself back in the late 1990s on a Lyson paper (rumored to be sourced from Hahnemuhle), but at the time I thought it was a product specific issue originating from a poor choice of packing tape that was use to seal the paper into the shipping package. It affected the top sheet only, and showed up in the print a few weeks after printing, but was unmistakeably in the perfect shape of the "outline" of the tape on the packing box. Since that time, the phenomenon has been experienced by many others, and some even believe that certain  "conservation framing" adhesives also cause the problem, although I've never seen the staining problem reported for acrylic "photo safe" adhesives. It appears to be light bleachable when in the distinct yellow condition, but I have also seen yellow-brownish variations that suggest continuing chemical changes which then become incompletely solved by light bleaching.   I suspect the bright yellow color is coming from elemental sulfur, and with an appropriate sample of the problem, a chemical analysis using analytical techniques like X-ray fluorescence would zone in on the yellow by-product. Then we could connect that species to the possible reactants. That the manufacturers haven't already investigated and solved this longstanding problem is possibly two-fold 1) the number of incidents that have come to their attention is better handled economically by sending some replacement paper than by going after the root cause, or 2), the root cause has been identified by the manufacturers and possibly determined to be an intrinsic function of the porous silicate microstructure (in other words, it's the nature of the beast).

I could probably talk my former colleagues at the analytical lab at Smithsonian Institution into running such a chemical analysis experiment, but I would need samples with well defined provenance (i.e, what paper and what adhesive was used that caused the problem). And I also need basic funding to pursue these matters and keep my research going, but I'm not a non profit organization, and even if I were, I currently have no safety net (e.g., tenured professor or museum staff position) propping me up financially while I pursue the long and arduous path of seeking grant money to do this type research. Bottom line: without a vibrant membership base at AaI&A, my options are pretty limited, and a large enough base of supporters to carry out this research just isn't there yet. The members I do have in the AaI&A digital print research program are really fantastic, very enthusiastic, and have sent me some very cool samples for light fade testing, so the concept of a subscriber-based research program with members contributing real-world samples for testing does work, but the vital number of members to sustain the effort financially is still a long way off.

As for UV blocking components, either glazings or coatings, here are some basic issues:

1) Coatings have to be very thick to achieve good UV blocking capability. None work as well as a UV blocking glazing such as OP3 plexi.  Print shield and other very low viscosity solvent coatings don't create enough thickness to block much UV. You have to apply a thick enough coating that the original surface texture is hidden almost entirely if not completely, and many printmakers don't want to turn their carefully chosen fine art paper texture into a "vinyl placemat".  So, the true value of a product like Print shield or Hahnemuhle Protective Spray has more to do with elimination of gloss differential and bronzing, plus it does act to some degree as a gas pollution barrier.  I personally suspect that the light fade studies that give such low viscosity coatings positive ratings for UV protection and increased light fastness are actually mis-indentifying what the coating is actually doing. It can impede gas penetration into the microporous coating, and in so doing, slow down oxidative reactions (light fading often being a photo-chemical oxidation reaction) on light fade test equipment that relies on high air flow rates over the substrate to keep temperature in control.

2). UV inhibitors of any kind, whether it be coatings or glazings, tend to shut down the function of OBAs in the paper, so if you like an OBA-containing "bright white" paper for your artistic vision, you are going to have to ensure that UV blocking glazings or coatings aren't added on top of the print in order to get the print to retain the "bright white" appearance you wanted it to have by selecting a high content OBA paper. Yet those UV blockers do extend light fade resistance for the inks, so no free lunch.

3). In order:

Glass blocks out 90% UV energy below about 330 nanometers.
Regular Acrylic - 90% UV blocking at about 360 nanometers
UV blocking (e.g OP3 plexi) -90% UV blocking at about 390 nanometers

UVA energy is considered to be energy within the 320-380 nanmmeter band. Hence, regular acrylic is far superior to glass, and OP3 plexi is far superior to regular acrylic plexi in terms of completely eliminating the active UV induced fading of artwork. However, the mythology that UV is the prime "light fade" inducing culprit is patently false. Blue wavelenth energy, albeit not as chemically potent as UV radiation, is generally available (and required for good color discrimination) at much higher levels than UV when looking at artwork, so its lesser potency is offset to a large degree by its greater abundancy. Bottom line is that even with UV aborbing glazing, light fastness is still an issue for long term preservation of artwork. AaI&A megalux-hour ratings provide a measure of the print's resistance to light induced damage. With decent knowledge of an artwork's resistance to fade, informed choices can be made on how to wisely display any kind of artwork, even artwork that is quite fugitive to light.

Ok, I think I will end there before this becomes a full blown conservation tutorial.

kind regards,

Mark
http:/www.aardenburg-imaging.com
 



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Lero

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« Reply #11 on: November 24, 2009, 02:47:08 pm »

Quote from: TylerB
I would encourage everyone to look into the activity at Aardenburg Imaging & Archives, in fact there is little excuse for members here to not be subscribers. I know Mark is aware of this problem because we discussed it. But I doubt he is in a position to research the reaction, define it, and repost to the rest of us specific results, for all kinds of reasons.
But, this continued confusion that the yellowing discussed here is in any way similar to the yellowing of paper we are used to. It's not the same at all, it's the coating, and it's reaction to certain evaporates and exposure to UV does indeed reverse it, Lero was correct.
Of course there are all kinds of other reasons to keep UV from your art.

A great deal of photographic output over the last several years may be vulnerable because this issue, and others related specifically to inkjet materials, continues to elude the community, even many experts.
Tyler

Thank you Tyler. I will go to the Aardenburg site. I am newly active on this site. I actually took down an entire exhibition (10 prints) and we carried them out into sunlight and watched the yellowing reverse over two hours. In the meantime we turned on the AC and open all the windows in the gallery and when we re-hung the work it did not happen again. There was some acrylic wall paint touch-ups that had been done the day before we hung the show. The next exhibition I was in they painted the walls three days before hanging the work. The same problem happened as the circulation was poor. The same solution worked. It was a different set of prints.
The yellowing mainly shows in light areas such as sky....blue sky turns green....

I spoke with the tech representative from Museo and he said he has often heard about this yellowing in Hahnemuhle photo rag paper due to environmental factors- ie.  a freshly painted room. He claimed that the Museo rag did not have this problem accept when outgassing has occurred from tapes such as duct tape. If this is the case then it may be time to switch from Hahnemuhle a leading archival paper to another paper.
That said, I will look at the Aardenburg site,
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howseth

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« Reply #12 on: November 24, 2009, 03:53:07 pm »

"If this is the case then it may be time to switch from Hahnemuhle a leading archival paper to another paper."

Premature, I think. Well, I hope.  I have not noticed this type of yellow staining, yet with Hahnemuhle Photo Rag Satin. Seems like there should be various work arounds for this staining, if it occurs -

Howard
« Last Edit: November 24, 2009, 03:54:38 pm by howseth »
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bill t.

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« Reply #13 on: November 24, 2009, 03:56:37 pm »

Quote from: MHMG
However, the mythology that UV is the prime "light fade" inducing culprit is patently false. Blue wavelenth energy, albeit not as chemically potent as UV radiation, is generally available (and required for good color discrimination) at much higher levels than UV when looking at artwork, so its lesser potency is offset to a large degree by its greater abundancy. Bottom line is that even with UV aborbing glazing, light fastness is still an issue for long term preservation of artwork.
Thanks for that.  I constantly hear from potential buyers who are absolutely certain that "UV Protective Glass" or "UV Protective Window Coatings" will allow them to display my pieces in areas that receive direct rays of sunlight.  There is a lot of public education that needs to be done in this regard.  When I am feeling sarcastic (which is pretty often) I sometimes tell them that matte black Krylon spray paint is the ideal coating for such situations.
« Last Edit: November 24, 2009, 04:02:48 pm by bill t. »
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Lero

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« Reply #14 on: November 24, 2009, 04:16:48 pm »

Mark, Thank you. I began replying before your reply posted.

Before knowing what I know now, I framed and mounted my prints without any plexi or glass to seal them in.
It was for exhibition and I thought it would be safe for the short term. The surface of the paper is so beautiful.
24 hours later..
My gallery called and said your prints are green....
The prints were wide format approx 40 x60 and the yellowing was throughout most of the prints.
The yellowing was actually in all of the highlights- most noticeably in the sky. Any prints with a light muted sky was affected. Bright blue skies were not.
Rather than looking yellow it looked green- due to mixing with light blue or gray blue.
Also it was mottled in terms of how the Print Shield covered the paper. You could actually see the spray come to life- similar to invisible ink kids play with, when it suddenly shows up.

It did not seem to be related to an adhesive as there were no adhesive marks. It seemed definitely the pollutants in the room- the fresh paint.
After airing out the room much better and putting the prints in sunlight to reverse the affects they held up without noticeable change for the two months that they were hanging. They hung again for two months without glazing and were also visibly unaffected by the air and natural light.

I am just wondering if this issue is spefically Hahnemuhle paper or all porous digital photo papers. This was photo rag bright white 310 gsm.
I will consider changing papers but I have two prints that need to be mounted and framed as they are already sold and I will not be able to start testing with new papers yet. They are mostly dark inks. I would like to advise my client on how to best frame the work.
He would actually like to use diasec, face mounting plexi. I thought this was not possible with porous prints but apparently it is with a silicone adhesive.

My preferred and less expensive framing suggestion is to frame them with archival matt board backed with Bainbridge archival foamcore for strength. I will then use a plexi. Maybe not the UV plexi.
UV plexi inhibits the affect of OBA's (as long as they work) if I understood you correctly.
I am not sure about using print shield anymore. I had thought it a good idea but now I will have to read up more on this.
When behind glazing , maybe unnecessary....

Your assistance is invaluable. I am new to this site and applaud your help and any funding you can get to carry out proper testing. There must be grants.......

Thank you-
Lero






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TylerB

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« Reply #15 on: November 24, 2009, 04:23:18 pm »

Quote from: Lero
...I am just wondering if this issue is spefically Hahnemuhle paper or all porous digital photo papers...

I have seen it in both Epson papers and coated Somerset... don't know about "all".

Mark, thanks for jumping in, I wasn't trying to coax a busy man out, honest <G>. And I also don't think this is something that should be falling in your lap, it should be the manufacturers... I hope I didn't imply otherwise.
Tyler
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Ernst Dinkla

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« Reply #16 on: November 24, 2009, 04:30:14 pm »

Quote from: Lero
I think you are right re: wrong course using UV light for bleaching. It's just that I had two exhibitions in which I had mounted and framed the work without glass or plexi but I sprayed them with print shield which also gives UV protection. Within 24 hours of hanging the work there was a yellowing in the prints due to contaminants in the air. (room was painted a few days before in one case and small paint touch-up job in another-acrylic paint). Both times I carried the work into sunlight and that reversed the yellowing. We aired out the rooms better, re-hung the work and it was fine. So I thought- if ever there was yellowing by some mysterious unforseen force it could possibly be reversed if the plexi was not UV plexi.
Also I spoke with Hahnemuhle and the technician said the spray "finishes the job". That it helps the print somehow become more complete or more fixed into the paper. He recommended  the spray for every finished print.

My thought was to spray and then use a frame with plexi glass but not a UV plexi...just in case. I will look at the Wilhelm tests but I always have difficulty with the site especially with Hahnemuhle photo rag bright white matt paper. The PDF came up blank every time. Will try again.

Thank you.

I have experienced the staining of matte papers like German Etching (in its expensive Lyson disguise) probably during Xmas 2000. Candles and a fire and the print more towards brown than yellow two days later. Considered it a loss then. Reported it on the Leben list as a problem. I suspected that the coating attracted smoke etc. That it is reversible with UV light is new to me and I doubt it would have worked on that print . The UV method still has its problems as sketched. Where you write acryilic paint being the cause I think you should think of Latex / Vinyl components in the paint. More sulfur related stuff.


met vriendelijke groeten, Ernst Dinkla

Dinkla Gallery Canvas Wrap Actions for Photoshop
http://www.pigment-print.com/dinklacanvaswraps/index.html




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Ernst Dinkla

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« Reply #17 on: November 24, 2009, 04:48:07 pm »

Quote from: MHMG
I personally suspect that the light fade studies that give such low viscosity coatings positive ratings for UV protection and increased light fastness are actually mis-indentifying what the coating is actually doing. It can impede gas penetration into the microporous coating, and in so doing, slow down oxidative reactions (light fading often being a photo-chemical oxidation reaction) on light fade test equipment that relies on high air flow rates over the substrate to keep temperature in control.


kind regards,

Mark
http:/www.aardenburg-imaging.com

Something I suspected too after reading this:

http://www.icn.nl/getasset.aspx?id=2604

Spectral curves at the bottom.

In Dutch though (there must be a dictionary in Aardenburg;-) but referring to Thomson's "The Museum Environment"


met vriendelijke groeten, Ernst Dinkla

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MHMG

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« Reply #18 on: November 24, 2009, 04:53:02 pm »

Quote from: TylerB
Mark, thanks for jumping in, I wasn't trying to coax a busy man out, honest <G>. And I also don't think this is something that should be falling in your lap, it should be the manufacturers... I hope I didn't imply otherwise.
Tyler

As the saying about a plate of ham and eggs goes "The chicken is involved, the pig is committed". I don't mind being involved or even committed. Experiencing and documenting real-world failures in the field is very often the key to isolating the problem in the laboratory. Were it not for real-world anecdotal evidence of problems with photographic materials, we'd have no need to develop any new print permanence tests. And sometimes the problems are very difficult to duplicate in the lab. Traditional RC B&W papers, for example, have a light-induced silver tarnish problem that was not discovered when the new RC papers were being developed. Only by witnessing persistant failures of the product in the field, did manufacturers learn that they had to add anti-oxidants to the polyethlene-titanium dioxide whitening layer in order to counteract free-radical induced oxidation of the image silver caused by light exposure of the TiO2.  Baryta papers never had any such problems.

So from a technical standpoint, it's personally very interesting to me to keep abreast of what end-user troubles are with any imaging technology, though simultaneously disconcerting that a problem of any kind is happening to the end-user.

kind regards,

Mark
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