Info on UV damage to black-and-white prints

[Doremus Scudder]

I'm looking for some sources about the effects of uv exposure on traditional silver-gelatin black-and-white print materials. I don't seem to be able to find much very easily on the web nor in my library. I'm hoping the experts here can point me toward some articles, papers, etc.

Best,

Doremus

 

[Nicholas Lindan]

Image Permanence Institute | RIT

www.imagepermanenceinstitute.org

I don't know that they have UV/B&W data, but if anyone does, they should.

 

[BrianShaw]

Another potential resource, although I did not scour for this exact question:

Wilhelm Imaging Research

Wilhelm Imaging Research in Grinnell Iowa is an authority on archival and preservation for the photographic, digital, and printing industries.

www.wilhelm-research.com

 

[reddesert]

A reference, not technical, but with links to some more supporting material: https://www.loc.gov/preservation/care/light.html
These are mostly from museum oriented publications and addressing the question of balancing display light levels vs degradation of exhibited materials.

 

[Doremus Scudder]

Thanks everyone! I've got some reading to do.

Doremus

 

[BrianShaw]

This might speak directly to your question. All seem very technical. You should be able to access and, if not, I can send it to you via email.

https://www.proquest.com/docview/2606200160/fulltextPDF/5A1D15D0A66849F8PQ/1?accountid=6749

This, also:

https://norcaloa.com/IRNM/articles-in-press/IRNM-103025

And this, but getting access might need an institutional access mechanism:

EBSCOhost | 147892829 | ASSESSMENT OF THE PHOTO-CHEMICAL DEGRADATION OF SILVER GELATIN PHOTOGRAPH PRINT-OUT.

web.s.ebscohost.com

This one might be better suited to anyone who may not be a "brainiac"; It's a bit more distilled to specific display guidance:

http://download.aaslh.org/AASLH-Website-Resources/ccaha-guidelines-for-exhibition-light-levels.original.pdf

 

[snusmumriken]

I appreciate you are looking for technical studies and expertise, but - depending on the reason behind your research - practical experience might be relevant too?

Everyone must have b/w family portraits where the print edges under the over-mount demonstrate how much the rest has faded in a lifetime. I have a print hanging on the wall that has been exposed to strong sunlight for about 30 years. The print was "archivally" processed by me following the best available advice, and toned with selenium toner. It has faded quite dramatically, to a more purplish tone and greatly weakened shadows. (You could argue that I didn't tone it for long enough - there has been a thread about that here - but the colour change from longer toning would have been objectionable.) Other prints made at the same time but stored in folders have not deteriorated noticeably. So a pragmatic approach for silver-gelatine prints (and for photos far better than mine!) might be to make multiple copies to be stored differently with different shelf-life expectancies. Else venture into the (stunningly beautiful) platinum process. But even then there are things that might eat the gelatine or paper base in storage.

I hope this won't start a dust-up on your thread, but isn't there a philosophical dilemma here of whether one wants photographs to be seen, or to act as a kind of time capsule to be discovered later? Also, don't you just hate those galleries where you have to creep around in near-darkness because they're afraid of exposing the art to any actual light?

 

[Doremus Scudder]

Brian,

Thanks for the links. Very informative articles if one can wade through the bad English (e.g., "appearance basin" for developer tray...). I've bookmarked them for the future.

Best,

Doremus

 

[GRHazelton]

Our Library of Congess should have some good information. Here's the link:

Care, Handling and Storage of Photographs - Collections Care (Preservation, Library of Congress)

How to care for your print photographs, including how to find a photograph conservator.

www.loc.gov

Note that the info is NOT for digital images
I have several gelatin silver prints under glass in subdued room lighting - not direct sunlight - which are unfaded after some 50 years. They were processed to the best contemporary standards. not toned in any manner, and then dry mounted on acid-free mat board. Today I probably would have avoided the dry mount process, so that they could be easily re-mounted.

 

[AgX]

Possible damage to:


-) the paper base as such (yellowing, getting brittle)

-) the dye of coloured paper base (decolorisation)

-) the gelatin (getting brittle)

-) dye of a dyed gelatin

-) dye of a staining developer

-) the silver by photochemical attac

-) toner in a toned image by photochemical attack

-) the PE foil in RC-paper by photochemical attac (officially meanwhile a no-problem)

 

[Sal Santamaura]

...I have several gelatin silver prints under glass in subdued room lighting - not direct sunlight - which are unfaded after some 50 years. They were processed to the best contemporary standards. not toned in any manner, and then dry mounted on acid-free mat board...

As do I. Which provides absolutely no information about how today's darkroom papers might perform under the same conditions. Especially given how loaded most of them are with optical brightening agents, which can "wear out" from UV exposure.

 

[gone]

Like Sal said, it pays to research things with RC papers. OB's are bad news, you don't want those, the're fugitive. With fine art papers, they tell you about this up front (there won't be any OB's in those). With photographic papers, you may need to dig deeper to get the correct info. If the prints are facing a window and get regular exposure, even w/ the glass window and glass on a framed print, all bets are off. That's not a good idea.

See the stuff below that I copied and pasted from a research site after wading through lots and lots of reading. This is their conclusion, and it is very interesting, and very scary. The last two sentences grab your attention, especially if you like to lie on the beach for hours in the sun. Free radicals, molecular rearranging, whoa!

"By analyzing the ultraviolet spectrometer, it was found that the damage occurred in the form of dissociation in the double bonds and the bonds of the salts that make up the gelatin molecule, i.e. an almost noticeable breakdown in the protein structure of gelatin.

While FTIR analysis confirmed that gelatin is somewhat resistant to ultraviolet rays in the short term, the effect of long-term UV accumulation can be observed because of rearranging the molecular network of gelatin, as UV rays encourage radicals. The free gelatin molecule has a role in rearranging the molecular structure of individual gelatin molecules"

 

[Sal Santamaura]

As do I. Which provides absolutely no information about how today's darkroom papers might perform under the same conditions. Especially given how loaded most of them are with optical brightening agents, which can "wear out" from UV exposure.

Like Sal said, it pays to research things with RC papers. OB's are bad news, you don't want those, the're fugitive. With fine art papers, they tell you about this up front (there won't be any OB's in those). With photographic papers, you may need to dig deeper to get the correct info...

My post made no reference to RC darkroom papers. It applies to all darkroom papers, RC and fiber base. I've no idea what a "fine art" darkroom paper might be; everything fiber base you can buy today is on the same Schoeller base, which itself contains optical brightening agents (OBAs). Then the manufacturers put additional OBAs in their emulsions, some more than others. The least I've found is Bergger semi-glossy warm tone, the most in Ilford Multigrade FB Cooltone.

Beyond OBAs wearing out, we have no data concerning composition and life expectancy of that universally used Schoeller base. Whereas those working with inkjet or alternative process printing can find out what their media are made of (cotton rag, alpha cellulose, etc.) darkroom printers are totally, ahem, in the dark on that score.

Bottom line: extrapolate not about today's darkroom papers from experience with prints 50 to 100 years old.

 

[GRHazelton]

IIRC the prints I mentioned in my post were made on Ilford fiber paper, single grade, generally semigloss.+ Whether or not they had optical brighteners I don't know. They were made in the early 1970s. again IIRC.

 

[Doremus Scudder]

First, thanks to all for the great info.

Optical brighteners seem to be ubiquitous in today's photographic papers. However, I've read research (Ilford, I believe) that indicates that the OBAs wash out with extended washing; hence the striving for shorter wash times. For my part, I wash long and longer just to remove the majority of the optical brighteners.

I find it interesting that the damage caused by UV exposure is largely to the gelatin in the emulsion and to the paper base itself (however, this latter seems to require that the back of the print be exposed to UV in the same way that the emulsion/image side, which is rarely the case in real storage and display situations). The silver image itself, especially if toned, holds up rather well.

Still, I'm amending my recommendations to customers and advising that they invest in UV-blocking, anti-reflective coated glass for display in areas with potentially high levels of UV.

Best,

Doremus

 

[Sal Santamaura]

...I've read research (Ilford, I believe) that indicates that the OBAs wash out with extended washing; hence the striving for shorter wash times. For my part, I wash long and longer just to remove the majority of the optical brighteners...

Some decades ago lford made a big marketing deal of the fact that it had begun using "anchored" OBAs that don't wash out with extended wet times. I suspect the striving for shorter wash times is more related to water shortages in many of its major markets.

...I'm amending my recommendations to customers and advising that they invest in UV-blocking, anti-reflective coated glass for display in areas with potentially high levels of UV...

Might as well not bother. The plastic coating of so-called "museum glass" imparts a yellow (sometimes slightly pinkish) cast. Worn out OBAs or degredation by glazing: both are "poisons" I'd prefer not to pick one of.

In my opinion, you'd be better off offering your customers a guarantee of free replacement if any purchased print degrades, assuming reasonable display conditions. Carefully define "reasonable!"

 

[AgX]

Optical brighteners seem to be ubiquitous in today's photographic papers. However, I've read research (Ilford, I believe) that indicates that the OBAs wash out with extended washing; hence the striving for shorter wash times. For my part, I wash long and longer just to remove the majority of the optical brighteners.

But this would not work woth RC papers.

 

[Doremus Scudder]

But this would not work with RC papers.

Assuming that optical brighteners are incorporated inside the resin-coated base, yes. I'm not sure that is the case. If the OBAs are only in the emulsion, then they would wash out with extended washing (unless they are "anchored" as Sal mentions...)

 

[AgX]

Yes, dyes can be anchored in different ways in a matrix like gelatin or paper pulp.
Whether this approach makes sense though depends on the use.



Optical brighteners located in the paper proper would have to cope with either the baryta layer or a pigmented PE-foil.