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Wednesday, 16 February 2011

Comments

Good essay, Ctein.

Go to a real framer (I'm a frame maker), not one of the big boxes, as you will be misinformed. I've heard way too many "horror" stories. Some of the new glazing options are are almost invisible, though expensive.

In the painting conservation field, there is some effort by some museums to "enclose" some paintings, in spite of evidence that the outgassing of various materials creates problems. My point is that even the folks who should know better, don't, always. Hubris.

Thus, do your own research, if this is important.

Bron

But wait, is that Wilhelm Imaging Research, the same Wilhelm Imaging Research that does testing for those major printer and paper companies. There may have been some doubts, are those results indipendenly achived or is there some marketing boost alongside. But who knows may be I've got it all wrong!?

Does the same criteria apply to both color and B/W prints?

Your comment to not use buffered materials is interesting. When I was looking to frame my dye-transfer print from Ctein’s print offer (thanks again!), I went to almost every framing place in town. And inevitably when I asked for non-buffered materials, I got the “dear in headlights look”. Most places didn’t understand what I was asking and swore up and down that buffered, acid free was the way to go for everything. Granted, many of these places didn’t deal with many photographs, but I was surprised to many high end framing places were so uninformed. I eventually found a place that understood what (and why) I was asking, and they did the job just right. But it does confirm “Sheppard’s Rule of Specialty Services”; if the so called expert knows less than I do, take my business elsewhere!

Ctein, what about a protective spray, like the one Hahnemuehle offers?

Peter, Wilhelm Imaging Research does the testing for all the manufacturers. How do you think they would reconcile adding numbers for all of them? Somebody would complain if somebody else receives a more favourable treatment. Unless the manufacturers agree upon a number beforehand, in which case we are screwed anyway, regardless of what WIR says.

@ Ctein,

there's a further, and IMO huge variable, and that is where the print is displayed, and how much direct light it receives from the sun. I'm not enough of a collector to have special storage arrangements, and all pictures in my house are on the walls to be looked at. Therefore to me positioning is key: I have a conflict between wanting to avoid direct sunlight, and the silly idea of bunching all the pictures on the shady wall and leaving the other 3 walls in a room bare.

The solution that is working so far is to put the oil paintings on the sunny walls - they look better under sunlight anyway, watercolours on darker walls but lit directly with "daylight balanced" bulbs in special picture lights, and photographs (either proper print or inkjet) under glass and on darker walls. This solution is entirely instinctive: no science behind it at all, but I hope it works into the future.


Ctein: you say: "UV glass will improve that by another 60–100%, but that hardly makes UV glass a requirement; we've already entered the range of museum-standard permanance well beyond what you could be confident of achieving with a traditional print."

Could you expand on the basis for the last half of that statement, "well beyond what you could be confident of achieving with a traditional print."

Please excuse my ignorance, but on a related topic, I've been searching for a reliable answer to the best way to keep prints in a box. Are sleeves recommended, or just the prints. If sleeves are recommended, is there anything to consider?

And for those interested in more in-depth data on papers and ink longevity (and the way to measure and describe it), one may visit http://www.aardenburg-imaging.com/

Could someone explain what buffered materials is/means? Thanks!

On Chris Sheppard's comment, I have a good friend who is a museum paper and photograph conservator (and for years I have specialised in photographic archives, as well as being a photographer).

The one thing I know is that 95% of "professional framers" drive her nuts, especially (but not only) with regards to photographs. They simply don't know what they are doing as far as conservation standard mounting and framing goes.

As far as the comment on Wilhelm's numbers go, first he is a world renowned expert on the longevity and conservation of traditional photographic and moving picture materials.

Secondly, there are very few others doing the same level or amount of testing and research, so basically Wilhelm is what we have.

From what other research I've looked at over the years in conservation institutes across Canada, the US, Europe and Japan the indications are that Wilhelm's figures seem to be pretty much in the ballpark.

Wilhelm is also aware of the limits of his own testing and of various factor effecting the longevity of inkjet materials that still aren't - or aren't yet - taken into account.

(Remember Wilhelm was also pretty much the one that showed the much touted and widely accepted figures for the longevity of Cibachrome/Ilfochrome prints were nowhere near their actual longevity by a pretty large factor)

For people interested in conservation issues (archivalness and durability) there's a forum called Amien here: http://www.amien.org/

It mostly deals with painting, but there's also a photography sub-forum, not much used but with some interesting entries. There's a lot of stuff about the longevity of pigments, if you browse through it. The people who run the organization will promptly answer technical questions. The main personality behind the site is Mark Gottsegen, who wrote the widely used "The Painter's Handbook."

In painting, you can get a bit of long-term protection by varnishing with a removable varnish. The varnish itself may yellow over the years, but when it's removed, the painting somewhat recovers to its original color (See Rembrandt's "Night Watch", which is actually called "The Shooting Company of Frans Banning Cocq" and wasn't actually at night -- it was assumed to be at night because it had darkened so much over the years, but when the varnish was removed, the color came back.) I've wondered if this same technique might not work with pigmented photos, to give it a kind of "airtight" finish. You remove and reapply the varnish every fifty years or so...It's a very well established technique in painting, even used occasionally with acrylics. Don't know if it would work with photos -- maybe Ctein does.

I don't know why a nitrogen-filled frame would necessarily leak, if put together with modern materials. You can get nitrogen filled tires at a Porsche dealer and they don't leak - much.

JC


Thanks to Mike for clarifying that the article was specific to colour ink-jet and not referring silver gelatin.

Cheers,

Walter

See also http://www.aardenburg-imaging.com/index.html for research on image permanence

The challenge to me is to be able to produce some images that people will be interested in looking at for seventy five years.

Forgive me for nitpicking, but buffering is done to minimize pH changes made by the addition of acids, bases (i.e., an alkaline substance) or dilution. At the risk of oversimplifying myself, a buffer consists of a weak acid and a weak base. Any acid added reacts with the base, while any base added reacts with the acid, but the pH of the solution remains relatively stable for moderate additions. You can make buffers over a wide range of pH values from acidic to alkaline. There's more to it, but I'll spare you the details.

mwg,
That may be, but when you're talking about rag mat board, I believe buffering just refers to the addition of magnesium carbonate or (more usually) calcium carbonate to raise the pH into the alkaline. I'm not a paper conservator, though--maybe we will hear from one?

Mike

Ctein,
While we're on the subject I sure love some mounting suggestions. Have been using Harman FbAl or similar semi-gloss papers from 24 and 44" rolls, and having a heck of a time in keeping them from crinkling. I've been hinge mounting them, but from a side the ripples are annoying. I'd love to hear your thoughts about dry mounting or other ways of keeping large inkjet prints flat.
Thanks.
Paul

Dear Mark,

Thanks VERY much for adding your valuable comments. I want to elaborate on two of your points, for emphasis.

Nonlinear fade rates is a VERY big deal. It's why it means nothing when a photographer sticks some prints in a sunny window for a year and pronounces that Print A will outlast Print B by a factor of 2. Put those prints on display under normal conditions and the rankings can reverse. You don't even get good relative information, when your test conditions are far removed from your real life ones.

Because life is full of uncertainties and surprises, we're always talking about averages and estimates. Often prints will show surprisingly long... or short... lifetimes in the real world.

It's a lot like people. On average, if you live on junk food and smoke a pack of cigarettes and drink a quart of rum a day, you will not live to a ripe old age. But that's only average. We all know folks who live "unhealthy" lives for a very long lifespan, and health-conscious, athletic folks who have a fatal coronary or stroke in their 40's.

That does, of course, not make the former practices advisable.

pax / Ctein

Dear PeterV,

Yes, you have it all wrong. Henry has a superb and long-standing reputation for independence and objectivity in the field.

~~~~~~~~

Dear John,

OK, I'll bite-- WHY do they sell nitrogen-filled tires (other than to part folks from their money, I mean)?

As you noted: don't leak - much.

Not good enough when you are talking a century.

You can make truly hermetic enclosures. It's hard. And expensive. The frames leak because it's in the nature of joints and seals to leak. You have to work very, very hard to prevent it, especially on the century time scale.

Anyone here who actually thinks they've got an airtight frame--does the glass bow in and out with changing barometric pressure? If not, it ain't.

Don't know much about lacquers. They've had a checkered past in photography. Maybe the new ones don't do any harm. Whether they do any more good that simple glazing would do? I dunno. Maybe there's something about this on Mark's or Henry's website.

pax / Ctein

"OK, I'll bite-- WHY do they sell nitrogen-filled tires (other than to part folks from their money, I mean)?"

It's really about the lack of moisture in the nitrogen, which means that the air pressure does not change as much when the tire heats up.
Buying a tank of nitrogen is simply the cheapest way to get a supply of inert dry gas.
It's a much bigger deal for race cars than for normal street driven cars however.

@ Mike 1933
To overdo mwg's point. Warning pedant alert.
Using a buffer changes the pH and more importantly makes the paper resist pH change from outside influences.
Calcium carbonate (a weak acid H2CO3-CO2 in water plus weak base Ca(OH)2 or lime)added to paper in production changes the pH to a desirable alkaline level (pH 9.0 for the pure chemical CaCO3 in H20 used as an antacid buffer in the stomach)but requires a fair amount of chemical and addition of a lot of it results in the paper becoming the pH of the buffer solution which is designed to be desirable. More will not make it very alkaline. Adding lye or sodium hydroxide to the paper production could make the pH just as high with less chemical (cheaper) but it takes just a small amount and the more you add the more the paper reaches the lye pH of 14- not good. So a tiny amount of lye would make my lye paper(likely equivalent to unbuffered paper) the proper pH.
When my lye paper meets atmosphere CO2 the sodium hydroxide and CO2 combine but recall we need just a few molecules of lye to make the paper alkaline and CO2 builds up in the paper so that the paper contains a lot of weak acid H2CO3 and a tiny amount of Na2CO3(a basic salt) which is an overall acid situation. BAD.
In buffered paper as mwg noted the H2CO3 from the air combines with the large amount of buffer and resists pH changes. Good.
Buffers change the pH of a solution to their pH but also resist perturbation of that pH by outside influences.
NL

"If you can exclude oxygen and water from the print environment, even exposure to UV-rich light doesn't cause prints to fade significantly faster than they do in the dark."

That's interesting. I wonder how Charles Duke's family polaroid is doing up there at the Apollo 16 landing site?

Ctein commented: "Don't know much about lacquers. They've had a checkered past in photography. Maybe the new ones don't do any harm. Whether they do any more good that simple glazing would do? I dunno. Maybe there's something about this on Mark's or Henry's website"

I believe Henry has some test results on the Premier Print Shield Products on the WIR website indicating they improve light fastness. AaI&A also has some coated samples in test. The AaI&A website recently converted from a subscription site to a free/donate site, so you can now register for free and get access to all the test reports. There's a column in the AaI&A database for coating/laminates where you will be able to locate the coated samples. Also, I try to test side-by side with a matched but uncoated sample so look for these sample pairs in the test results as well. Each sample has a unique ID number.

Microporous inkjet media are much more prone to oxidative reactions and reactions with other air-borne contaminants compared to swellable polymers like traditional gelatin prints because their coatings are by design very porous to suck up the ink fast. Hence, sealing with a thin solvent-type acrylic spray coating like Hahnemulhle Protective Spray or Premier Print Shield usually improves light fastness and gas fade resistance by a good margin even when the print is also framed under glazing. It has little if anything to do with UV blocking as is often claimed. It has to do with the physical sealing of the micropores. That said, early trends in my tests also suggest that some of the water-based acrylic dispersion coatings may have some adverse reactions at times with the ink but not always. Thus, one has to test the specific printer/ink/paper/coating combination to make sure it's got chemical compatibility (i.e. the coating does no harm). Lastly, as Ctein says, the notion that a coating or picture framing method provides a perfect hermetic seal is wishful thinking, but nevertheless even a quasi seal can under the right circumstances improve longevity by providing significant improvement in the microclimate surrounding the image bearing layer.

cheers,
Mark
http://www.aardenburg-imaging.com

Does anyone know of a source for convenient, ready-to use mailing enclosures for the safe shipping of unframed prints in typical sizes such as 22"x17" (most papers) or untypical 25"x17" (Harman Gloss Baryta)?

I don't know why a nitrogen-filled frame would necessarily leak, if put together with modern materials.

I work with experiments in high-ish vacuum daily. The chambers are made out of 25 mm stainless steel for the most part. They leak.

In a past life, I worked with detectors that needed to be kept oxygen-free, so were bathed in nitrogen. They leaked.

I guarantee you that you are not willing to spend as much money on a picture frame as we did on the vacuum/positive pressure nitrogen for these experiments. Why wouldn't a $100 picture frame leak? Increase the cost by an order of magnitude. Two, if you like. O(3), and you're getting up to some very expensive art. It's still going to leak.

It's also going to be difficult to see your collection through several millimeters of stainless steel.

Ctein - would appreciate any suggestions you have regarding mounting inkjet prints when framing. I've generally used a hinge, is this the most appropriate or are there equivalents of dry mounting we use with fibre-based B&W prints?
Thanks for any help
David

This may be anecdotal, but I have prints from the original Epson Stylus Pro (2000) that were sprayed with Krylon clear acrylic and displayed in a plastic frame on a desktop in a corner office (southern exposure, 2 walls were glass) for a number of years without noticeable fading. The pictures are at home now, but still look fine. A print that wasn't sprayed but was sealed in adhesive plastic sheets and similarly displayed show some fading over the same time period. Several unsprayed, unprotected prints stuck to my sister-in-law's refrigerator (no direct exposure to sunlight, only one small window in the e room) faded very severely (magenta nearly gone, cyan 75% gone) in a matter of a few years.

Interesting. I checked the Wilhelm Research site and there are two kinds of info. One is what Ctein said about lacquers, not really good - but on silver paper. The other is inside tests results. For instance, this test of Epson 7900 from the last year. (The link goes directly to a PDF.) It shows that a protective overcoat - as they call it - generally lengthens the life of the print.

The final and exact result depends on the paper and the display conditions, though. For some papers and some conditions, the longevity of the print increases for about 50% of the paper without the overcoat. It's the same for all the Epson printers I checked.

The point I wanted to get across was that a buffer doesn't have to be neutral. You can adjust the pH of a buffer by changing the ratio of acid to base and by changing the type of acid and/or base. Each acid or base is effective at buffering over a range of pH values (although not all are effective in a buffer). In this case, the carbonate is acting as a base, and I believe the acid is already present in the paper.

I promise keep my mouth shut if the topic of depth of field comes up.

Before we let this get too far, spraying any kind of gunk on any photograph not your own would be completely, totally against the basic precepts of all current thought in the field of paper and photograph conservation.

I'll bet you could get a conservator to actually recoil in horror at the idea. I mean actually, physically rear back in her chair and stare at you with her mouth open. Just a guess.

The basic rule is "don't do anything that can't easily be undone."

You can do anything you want to with your own photographs--you're the artist--but for heaven's sake don't "lacquer" anyone else's photographs if you have any regard at all for the proper conserving of objects.

Mike

"I promise keep my mouth shut if the topic of depth of field comes up."

Made me laugh.

Mike

I admit that I am spoiled by being able to hold my own, and my friends', photo prints in my hand to look at them. No glass, my choice of lighting, and at the distance I wish to observe from.
While displaying photo prints, silver or inkjet or whathaveyou, under glass is an accepted practice, it really is a regrettable way to LOOK AT photo prints. The glass surface, with it's light absorption and reflections, seriously degrades the view of the print in almost all viewing situations. Add to that the ghastly dim and off-color(2300ºK, anyone?) lighting in many/most galleries and museums(as I experienced recently at the Los Angeles County Museum's William Eggleston exhibit), and the glass just further degrades the experience.

Sort of off topic, but pertinent -
Nitrogen filled tires have less water and the gas is more inert compared to atmosphere. That keeps the air pressures more stable over a wider heat variance. There are several large tire dealers that offer this service at no charge.

In response to someones comment about how Wilhelm testing everyone's, no. I think it is $10,000 to have them test it. I hear that there have been some resent tests from a big manufacturer that they do not want to release the results because they were so bad.

"Don't know much about lacquers."

http://www.guardian.co.uk/artanddesign/2010/nov/02/robert-bergman-photography

At Paris Photo last November I saw some of Robert Bergman's portraits that I had only seen online before. This is wonderful work. The prints were not like anything I had seen before, and I asked the gallerista about them. It turns out they are inkjets, and that Bergman paints over each one himself with a varnish/lacquer/emulsion/kind of thing that he makes himself....

Worth seeing if you have any being shown near where you are. It's a nice effect--the varnish is very thick and you can see the brush marks in it.

RP

Phototouch wrote: "In response to someones comment about how Wilhelm testing everyone's, no. I think it is $10,000 to have them test it. I hear that there have been some resent tests from a big manufacturer that they do not want to release the results because they were so bad"

The story seems unlikely because the "Big" manufactures all do extensive testing before submitting samples to an independent testing laboratory, often precisely replicating the independent lab's testing protocol. They know in advance pretty much what the outcome will be. (addendum: the ozone gas fading debacle with inkjet prints which happened several years ago caught both manufacturers and independent labs by surprise and new test protocols for gas fading had to be implemented). As for small third party manufacturers, well that's another story, but the high cost of laboratory testing usually precludes them from independent testing of their products.

The reality is that due to the labor-intensive nature of accelerated aging testing (which makes it expensive) plus the mix-and-match nature of material choices used by the end-user for inkjet printing, many popular printer/ink/media combinations will never get tested by fee-for-service labs. It's not really the testing labs' fault nor symptomatic of any large scale conspiracy by manufacturers to manipulate the market. Where I have trouble with vendors is when they make claims without proof or "proof" based on dubious testing methods. If they don't make any claims on product durability, then fair enough, it's a normal case of "buyer beware".

kind regards,
Mark

Dear Jim,

Thanks for the tire rationale.

I'd have to sit down with a few phys chem tables to see if any of that is actually true.

I can tell you the inertness of the gas has no effect on its pressure vs temp curve. It's still possible that pure nitrogen has a flatter pv=nrt curve than standard earth atmosphere. The difference might turn out to be esentially in the noise, though.

I'm out of town, so if some enterprising reader wanted to look up the gas constants for N3, O2, CO2, and H2O and figure if the atmospheric mix behaves significantly differently from pure N3, that'd be cool.

~~~~~~~~

Dear TPT,

Henry tests whatever he feels like, which is what was meant by "everything;" it was figurative, not literal. He does not have the facilities to test every single paper/ink combination made.

While Henry tests what he feels like testing, you can hire him to test your particular paper/ink combo. In the past, a condition of hiring has always been that Henry gets to publish the results-- they are not proprietary and you don't own the data.

pax / Ctein

I've seen beautiful large format inkjet prints but wonder their value/quality versus a lab-printed digital print. Cost is huge and I
wonder if anyone doing their own inkjet printing calculates this into their time and materials. For example, my lab charges, for a digital color 11x14, $7.18 and for same 11x14 archival inkjet print $51.30.
Now, I do get what I want, with my eye/monitor calibration so I understand the desire to control the finished product from start to finish.
My question is, what is the archival comparison of fine-art archival inkjet prints versus lab printed (LED printed, silver-based prints)?
All responses to my (further) (re) education on this welcome.

Labs seem to charge absurd amounts for inkjet prints. The inkjet printing service at the Minneapolis Photo Center (a non-profit devoted to photography) charges something like $0.10 per square INCH (meaning nearly $15 per square foot, so nearly $90 for a 24x36).

Costco, on the other hand, charges $10 for a 20x30 inkjet print (Epson 7880 printer). That's on a Fuji satin paper; unfortunately not one that's had Wilhelm testing, and since it has optical brighteners, it won't do too well. I wouldn't be surprised if it were as permanent as an RA-4 print, though.

The materials cost varies based on the paper of course, and is non-trivial. Ink is cheaper for the big printers (basically, you're buying in bulk). I haven't kept careful enough figures to have an answer I believe. I've heard people assert numbers in the $2/sq. foot to $5/sq. foot range for retail materials cost, using the better Epson-branded paper (and over enough years that inflation may be a factor). Anybody here have figures they want to share?

Digital RA-4 prints can be pretty predictable if the lab does it right, and makes the profiles available. I know people quite happy with the Adoramapix prints for example (the prints look good to me; I didn't have access to the files so I have no opinion on whether the prints match the files well). At this point, though, I consider RA-4 paper an inferior medium compared to modern inkjet color; not severely inferior, but not my first choice.

Jay Carey wrote: "My question is, what is the archival comparison of fine-art archival inkjet prints versus lab printed (LED printed, silver-based prints)?
All responses to my (further) (re) education on this welcome."

With regard to lightfastness properties, you can find some answers to your question in the Aardenburg light fastness database. You will need to register to gain access to all results (registration is free). Once you have navigated to the light fastness test results database, check out the Conservation Display Ratings column in the database for samples with ID #s 73-76, and also #79. These samples are replicated tests for independent batches of Fuji Crystal Archive II photographic paper (widely considered to be have the highest longevity of all "C-type" color photographic print papers that you are asking about). Next, after taking note of the Crystal Archive ratings sort the "Conservation Display Rating" column in the database in ascending order by clicking on the column's header label. You will then be able to find many inkjet printer/ink/paper combinations that are worse and many that are better (some much much better) in their rating.

The AaI&A Conservation display ratings are based on a tight failure crieteria set that evaluates early stage fading issues, ie. fading that is measurable but the viewer will still see "little or no noticeable fading" in the image. They are expressed in megalux-hours of accumulated exposure because AaI&A does not try to assume anything about end-user illumination levels, only the total exposure dose that no matter how long it takes to accumulate will result in the exposure dose measured in test. That said, a convenient rule of thumb is that if you divide the megalux-hour rating by 2, you will get "Wilhelm years" of predicted display time. If you multiply megalux-hours by 2, you will get "Kodak years" of predicted display time. Note, however, that both Kodak and WIR use a consumer-oriented fading criteria set that allows for "easily noticeable fade" at the test endpoint, whereas AaI&A uses a failure criteria set that only allows "little or no noticeable fade" for the conservation display rating because it is more appropriate for serious collectors, museum curators, etc. AaI&A then carries the testing further and posts the fading of the colors at uniform exposure intervals in order to let people visualize the early, middle, and late stages of fading as well.

The AaI&A methodology is a significant departure from other industry-accepted testing methods and a good reason for people to study the underlying assumptions used by the various testing labs to estimate the seriousness of the fading.

cheers,
Mark
http://www.aardenburg-imaging.com

Dear Mark,

Thanks for that additional info on lacquers. Makes sense- the way I would describe filling in the pores is not so much a "seal" as massively reducing the surface/volume ratio. Generally slows reaction rates (for lay readers-- the essential difference between a BBQ briquette and activated charcoal is the surface/volume ratio; that is what makes the latter so phenomenally reactive).

----------

Dear Jay,

You can find lifetimes for various chromogenic materials on Henry's website and in the book PDF I recommended previously. Doesn't matter if they are printed in the darkroom or with LEDs.

The difference in price you are seeing could be the difference between getting mass-produced prints and hand-corrected custom prints. Dunno, as I don't have any familiarity with their work. But custom labs frequently have several grades if print you can buy from "one cut above a drugstore" to "you get someone skill like Ctein doing your printing"' with all prints made on e same materials. Iow, it may not be the meat, but the motion.

Pax, Ctein

Ctein;

Not that area of study, so I wasn't speaking from an expert standpoint. As another posted, it's more a benefit in racecars than on the street. Changing air pressure affects the size of the contact patch. Blame the F1 guys for coming up with this. Porsche people . . .

jw

I admire the unbounded optimism and serious concern over inkjet print life in this thread. One wonders however, what the impact of the ever-increasing level of CO2 in the atmosphere has on the life of prints not to mention their viewers.
bd

PS I've found the big pop in framing cost comes from "non-reflective glass".

Dear Bob,

The rising CO2 levels are not a cause for concern, in terms of the direct health of either prints or their owners (indirect effects, as a result of climate change are another matter entirely, of course).

First, the concentration of CO2 is low, measured in parts per 10,0000, and the rate of increase is equally low. Second, CO2 is not a particularly reactive gas. Its most noticeable chemical effect is that it is slightly soluble in water forming carbonic acid, a very weak acid. The equilibrium constant of hydration is rather low; very little CO2 dissolves in water. Consequently, the natural level of carbonic acid in your home is quite low.

Third, personal human activities can easily raise the concentration of CO2 in an indoor environment to several times what it is in the external atmosphere. Poor ventilation and other living factors have a much bigger effect on CO2 levels around prints than anything else.

In summary, long before CO2 levels can be high enough to be of concern regarding print permanence, you will have far worse problems to be concerned about.

pax / Ctein

They're prints from digital files aren't they?

Why not just reprint them every twenty years?

Re: Nitrogen in tires:

Oxygen and its attendant moisture content was once a problem for tires used in racing conditions. Tire "tread" temps are routinely in excess of 200F, due to a combination molecular and mechanical friction and transfer from nearby braking systems. Seemingly insignificant (1/4 lb psi) changes in can make very pronounced changes in a tire's performance- not only in the shape of the contact patch (affecting adhesion), but also in its spring rate (affecting chassis dynamics).

Basically, engineers need the gas in the tire to be completely dry, so (pure) nitrogen it is.

It's also used in aviation (helium as well), for similar reasons, as well as to reduce the possibility of "tire explosion" caused by oxygen igniting in overheated tires.

There is a show at David Zwirner gallery of large "archival ink" prints by Philip-Lorca diCorcia which are framed but not glazed.

They of course look much better, than they could ever look glazed...

but the interesting discussion I had with artist friends who looked at them with me is -- about the delicacy of painting vs. these photos.

E.g. we think nothing of hanging a multi-million dollar Rothko without glazing, but we worry about ink-jet multiples (I will note the Philip-Lorca diCorcia prints were priced at $30k).

Just for the record I will not be living for another 100 years.

Hugh Alison wrote: "They're prints from digital files aren't they?

Why not just reprint them every twenty years?"

This rationale is perhaps the most common justification expressed by contemporary photographers as to why print permanence no longer matters.

Print permanence really doesn't matter... until it matters.

cheers,
Mark

"There is a show at David Zwirner gallery of large "archival ink" prints by Philip-Lorca diCorcia which are framed but not glazed."

On paintings, the varnish, which acts as a glazing, providing protection, is softer than the underlying painting; thus it can be removed and replaced with out damage to the art. The only way I can see ink jet prints working with out glazing would be a first layer, of a permanent barrier between the print, and top coat, then a much softer "varnish", that can be cleaned, and or removed and replaced.

Optically clear glazing, though expensive, might be a better choice.

The last featured comment, is from a staunch advocate of glazing paintings, by the way, so that Rothko may have it's day under glass. I disagree,about glazing paintings, but that's for another day. What he has to say about ink jet prints is from a framing industry expert, though, and I would only add that monitoring said prints should be regular, looking at them not as favorite images, but checking that no weirdnesses (technical term) are happening in that micro-environment.

"They're prints from digital files aren't they?

Why not just reprint them every twenty years?"

If I give someone a print how are they supposed to reprint it?

Dear Hugh,

1) It's hard selling artwork for any decent price that's going to fall apart in short order.

2) It's tedious reprinting old photos for no good reason other than to replace old prints. Been there. Done that.

Suppose you normally make one print a week, only one (hardly a lot for a serious hobbyist, let alone a professional). After 20 years, that's 1,000 prints.

3) Matching old prints digitally is easier than doing it in the darkroom (where it's essentially impossible after materials change). But it's not a cakewalk.

4) All the other reasons other folks mentioned.

pax / Ctein

It was a slightly facetious comment. Not sure if you do facetious that side of the pond.

As long as they last longer than me and the people I've given them to, I'm reasonably happy.

To be contrary, one of my main backups for my digital files is to have a nice large archival print.

Dear Hugh,

Not over the Interwebs, we don't.

Problem is that there is no remark you can make that is so outrageous or clueless that someone, somewhere, will not have said it in all seriousness.

Your facetious comment was one we have heard made sincerely. Sad to say.

Pax , Ctein

Just a little off to the side of the topic, but:

"In fact, the vexatious silvering-out problem with untoned B&W silver RC papers only occurs with framed prints."

If this refers to a metallic sheen on the shadows on older RC prints, then I have several non-reprintable ones that have this disease. I thought it was just me.

Is there any way to fix it?

Dear Paris,

Oh no, you're hardly alone.

BTW, this is one of the cases where I bet against Henry Wilhelm and lost. Now I know more about this than him, but it was knowledge gained at real cost.

No, there is no way to repair the physical defect, although digital restoration of this type of damage is straightforward (see here: http://photo-repair.com/DRBookPromo/DR_Excerpt3.htm).

pax / Ctein

I have the same problem posted lby Paul David back on 17 Feb except with Epson luster paper - I hinge mount under glass and get vertical "ripples" probably with variation is room humidity. Any Answers??

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