RA4 baryta papers: difficulty?

Discussion in 'Silver Gelatin Based Emulsion Making & Coating' started by timeUnit, Dec 21, 2006.

  1. timeUnit

    timeUnit Member

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    I'm wondering, how much more difficult is it to coat baryta papers with color emulsions for RA4 process, compared to coating with BW emulsion?

    Maybe it's a silly question... ?
     
  2. Photo Engineer

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    All color paper was on Baryta until the mid 60s, and then the conversion to RC began. This was done in the interests of decreasing pollution and processing time. Baryta absorbs a huge amount of chemicals and this must be washed out.

    The coating formula for many Baryta papers had to be adjusted with respect to RC due to the fact that Baryta absorbs chemicals from the emulsions and RC will not. Therefore, RC papers would keep better than the same formula on Baryta, and would be somewhat slower with the same formula.

    PE
     
  3. timeUnit

    timeUnit Member

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    Thanks!

    I'm guessing we won't see color baryta papers in the near future? :smile:
     
  4. Photo Engineer

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    Not unless we coat our own.

    PE
     
  5. Ryuji

    Ryuji Member

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    Many B&W printers still don't get this, but RC paper base can give greater reflectance and therefore slightly wider range of image tone. Combined with shorter storage/display life of dye image from RA-4 papers compared to properly toned silver image, I don't realy think there is a very good reason to make color paper on baryta base.
     
  6. timeUnit

    timeUnit Member

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    But still... the surface on an air-dried glossy baryta print would look pretty darn good on a color image... :smile:
     
  7. Photo Engineer

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    Current images from color RC papers are expected to last from 100 to 200 years depending on the keeping conditions and manufacturer. This has been achieved during the last 10 years or so, although overall image stability has been improving constantly for the last 50 - 60 years since the introduction of the first color imaging materials.

    This would probably not be possible on Baryta paper support. It is mainly due to the UV absorption properties of Baryta vs Titanium Dioxide used in the two products, but also in other factors involved in the RC/TiO2 base. For example, it is possible to incorporate antioxidants into RC support for stability that are impossible to add to Baryta.

    OTOH, B&W images in silver are apparently of similar stability on either Baryta paper or RC support and are limited mostly by the quality of the process and the stability of the paper. At the present time, Baryta paper images are known to survive for over 100 years.

    Early RC prints are not as stable due to the degradation of early RC due to UV and oxygen.

    Having been directly involved in the testing of these images from about 1965 - 1970, and having kept up with the studies thereafter, I am quite aware of the advantages and disadvantages of the paper, dyes and silver images.

    I might add that at normal viewing distance, you might not be able to distinguish between a color print on baryta support and a color RC print.

    PE
     
  8. Ryuji

    Ryuji Member

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    This depends not only on the material used, but also the test condition and interpretation of the data. It also strongly depends on the acceptable color shift or density loss used to determine the life of the image. There is no single valid set of criterion and test method, so that the published test results vary a lot even for the same material, such as Kodak Endura. Depending on the test conditon and interpretation, this same material is rated 20 years (stronger light, no UV filter, etc., used by Wilhelm) and a couple off hundred years (weak light, UV filter, etc., used by Kodak). Images on current Endura may last for 200 years in ideal refrigerated museum storage with molecular sieve, but in the storage condition of average consumers, I doubt that the image will go significantly faster.

    However, I also believe that modern RC paper base is a lot more permanent than earlier ones. I also agree that antioxidants added to the polyethylene resin are not usable in baryta sizing layer. Those antioxidants have to be nondiffusible but there is no good way to make hydrophilic nondiffusible antioxidants to add to baryta sizing, but it's easy to make nondiffusing hydrophobic antioxidants for polyethylene.

    Another consideration is that I have a final rinse solution that adds UV blocker and antioxidants to the print. (Similar idea to sunscreen protection but with extra antioxidants.) I'm not sure why Kodak or Fuji never came up with this kind of solution (perhaps cost consideration, as the ingredients are not very cheap), but this treatment is very effective with untoned silver images on RC base in my testing with UV and oxidizing agents.
     
  9. Photo Engineer

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    Kodak used an antioxidant buffer bath for years as a stabilzer. It was sold as Kodak Ektaprint Type II stabilzer. I have a patent on a modified version which is now used by several other companies for films. The Type II stabilzer greatly enhanced the stability of color paper, sometimes by over 2 - 5x depending on conditions.

    As for dye stability, I am quite familiar with the antioxidants in both the paper support (see patents by Venor et al) or in the coupler dispersions (see patents by Lestina et al). I helped develop the first color paper to incorporate the work of both of these people and others (see patents by Edens and VanCampen). I am familiar with the methods of testing and the reporting of them (See work by Tuite or Wilhelm or Kapecki).

    The questions of testing conditions involve the use of 200 fc or 500 fc for fade tests under light, and what ingredients to add to the gas mixture and what proportions for the high temperature and humidity tests. These are under debate between Fuji, Kodak and the standards committee.

    The most recent compilation of this was by Kapecki at the ICIS conference in May and discusses all of these issues and more. RIT has a very large lab entirely devoted to research on this subject.

    I have been tracking the subject since I was first introduced to it in 1965, and I have seen data going back to the 40s showing the history of this subject as it evolves.

    It is much too complex an issue to discuss here. It is like dipping a toe into the ocean and saying you are now an expert on marine biology.

    PE
     
  10. Ryuji

    Ryuji Member

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    Ron, I'm very familiar with the work you mentioned, except I don't know Ektaprint Type II stabilizer. Do you have a patent number or name of compounds used in this final bath? Does it also improve the image stability of modern papers with antioxidants incorporated in the emulsion layers, or does it work on a different mechanism?

    Anyway, the main reason I brought these up is really to make a point that there's really not much point in making baryta color paper. A lot of writers from 1990s criticized photo manufacturers to make more profit from RC than baryta, saving silver from emulsions, etc. and a lot of people seem to believe that those criticisms are valid. It's always hard to fight against common misconceptions but this is the time to do so.
     
  11. Photo Engineer

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    The silver content of emulsions coated on baryta vs RC was identical, as was gelatin level, but the addenda was varied to allow for the absorption of the addenda by the permeable baryta. Generally, keeping was far better on the RC and the same was true for B&W. The surfactant and water content was different due to the different properties of the two supports.

    The Type II stabilzer first used AEH, a type of sugar (a hepitatol), but this was found to be too variable, so it was changed to sorbitol. The sorbitol and the AEH increased the glass transition temperature of the gelatin and thereby provided a rather impermeable oxygen barrier. It made the prints stickier in humid environments too, and so it was recommended only for enlargements that were to be mounted not prints being stacked.

    The type II stabilizer was also at a different pH than the normal stabilzer. They were both discontinued with the Ektaprint 2 process. At that time though, AFAIK, the sorbitol could double the light stability of any paper regardless of whether the antioxidant was incorporated or not. It even improved the stability of couplers that made dispersions with high glass transition temperatures (again see Tuite et al).

    Photofinishers and professionals didn't want to work with the Type II stabilzer.

    This work was published by Edens AFAIK. It was also discussed by Tuite in a presentation at the SPSE conference in Washington DC in 1988 (IIRC), where Henry Wilhelm gave his first presentation.

    The only other recent references are the book by Jon Kapecki used as a text in the ICIS course and the presentations by Kodak and Fuji. That book probably does not mention the Type II stabilizer though. I forget offhand.

    PE
     
  12. timeUnit

    timeUnit Member

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    Well, I'll just hope for the manufacturers of inkjet papers to come up with a product that matches the look of an air-dried glossy baryta surface. What I've seen so far wasn't that impressive.
     
  13. Photo Engineer

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    Glossy Baryta was not intended to be truly glossy unless it was ferrotyped. I see ferrotyping as a lost art, but a properly ferrotyped Baryta B&W or color print will blow away an air dried glossy print any day.

    PE
     
  14. Joe VanCleave

    Joe VanCleave Member

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    Whose Paper Are We Talking About?


    Not to be argumentative (although I suppose posting a reply is intrinsically just that), but which current manufacturer of RC paper are you referring to? Is this reflective of your experience solely at EK, or does this statement universally apply, industry-wide across the board, to any RC paper I may choose to purchase in December of 2006?

    Since you stated that it depends, in part, on the manufacturer, can you be more specific, so as to help us laymen in making better decisions on purchasing RC paper? What about the easten European brands of B/W RC paper; do you hold the same degree of confidence as you do with the products no longer manufactured by EK?

    I suppose you can sense the frustration of, after eagerly lending an ear to the wisdom and sage advice of experts, to find their statements mostly opinion, with little of substance.

    How is this thread supposed to bolster our decision-making regarding the longevity of RC vs fiber paper? Granted, the context of this thread is about which papers to use for hand-coating, which is not in my foreseeable future, but the discussion seems to be relevant to commercially manufactured papers as well.

    Where do us laymen (and potential customers, the only ones who will keep this technology alive in the marketplace) find authoritative information on the keeping properties of such materials? Most manufacturers' websites give information, if at all, that reads more like a legal disclaimer than a statement of expected product performance.

    I may also state here that, as a qualified neophyte, the academic and arcane arguments between you and Ryuji seem to me to be nothing more than a battle of two egos. While it provides for some degree of entertainment in my otherwise miserable life, I am beginning to question the advocacy of relying solely on self-proclaimed 'experts'.

    I appreciate the candid and otherwise priceless wisdom that is (occasionally) dispensed here. And the historical lessons on the engineering developments of modern photographic materials are of academic interest to some. All the rest is chaff.

    There's nothing that beats experience; especially one's own!:smile:
     
  15. Photo Engineer

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    Joe;

    I don't take it as argumentative.

    My statement about the life of a color photographic material is based on several things. First, there is a statement on Kodak's web site regarding the longevity of Kodak Endura paper. Second, Fuji has made a similar statement to the photo industry. Third, Henry Wilhelm discussed this with me personally and his institute has published data on longevity. Fourth, the Image Stability lab at RIT is in general agreement with this data. Fifth, I took the ICIS course on image stability in May. And, last but not least is my more than 30 years experience as an engineer at Kodak, with about 1/2 of that time being involved in some way with image stability.

    Now, the disagreement in value centers around the testing method. You get different results with each paper depending on how you test it. And, the ANSI committee on image permanence has yet to make a definitive statement on this subject with definitive standards, so each lab makes its own standard.

    Nowhere in this thread was handcoating discussed that I know of. This was solely a discussion about manufacturing color products. They cannot be easily hand coated, although I have done it. It is truly a pain, and very expensive due to the chemistry and equipment needed.

    I do not wish to have an argument with Ryuji. I merely state facts from my actual hands-on experience along side his observations from the literature. Sometimes they agree and sometimes they don't agree. This is often the nature of printed material vs hands-on in engineering and should not reflect badly in any way on either of us.

    PE
     
  16. Ryuji

    Ryuji Member

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    As I see it, Joe is more interested in comparing the longevity of images produced with different paper products. There is clear difference between products here. But Joe may want to pay attention to the different test methods used by different manufacturers. Eastman Kodak uses different condition and calculation method to come up with the number of years their color prints will last in display condition. Most other companies (both RA-4 type paper manufacturers and inkjet printer manufacturers) use more severe testing condition and more conservative projection method. What it means is that if the number is the same, it means Kodak prints go before other prints.

    Another thing the consumers can consult is guidelines made for museum conservators. They consider RA-4 type prints "unstable" and the guideline recommends limited brightness of viewing light during display, and humidity-controlled refrigeration during storage. B&W materials are quite a bit more durable than dye-based color images, although some manufacturers (I won't say who, since Ron will go on forever if I do---maybe he will anyway, even if I don't) have better dyes and dye couplers than others. There are several books written on this topic, and there are at least a few if you count English language only. They are written for museum conservators, conservation scientists and technical staff so they are more accessible than papers published on journals, though you often need to consult the latter for more details.

    About the permanence of eastern/central european RC stock, I don't think anyone knowledgeable ion the subject makes a serious comment. RC paper production had several technical pitfalls that Kodak, AGFA, Fujifilm and Ilford got stuck several times. All of the problems are documented in various places, and you know what they are even if you are not an industrial spy. But figuring out how to iron out all the problems is not that easy... I'd definitely stick with products from above 4 until someone does thorough testing on others' products... but I am not hopeful that anyone will do such a task in this market situation.
     
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  17. Ryuji

    Ryuji Member

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    I'm not sure about that explanation. Glass transition temperature of gelatin is only lowered by adding small amount of sorbitol. Plus, I did this experiment myself some time ago and srbitol-treated gelatin is permeable to oxygen and peroxide. If sorbitol treatment indeed prolonged the image longevity I suspect it did so via radical scavenging action on excited dye molecues, or perhaps by scavenging the offending molecule or its intermediate forms.
     
  18. George Papantoniou

    George Papantoniou Member

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    I have a proposition to make :

    Print one negative on different colour papers (Fuji, Kodak, Eastern ones etc) and send them to me. I will place them on a rooftop in the center of Athens. They'll get 300 days of sunshine/year, pollution (NO's, SO's, Benzolium, heavy metals, CO etc etc) and acid rain (when it rains, that is rarely). In one years time, I bet most of them will have "gone"... we can then compare them to see who'll be the winner (if we can clean them of the filth that'll have been deposited on them).

    The processing of the prints has to be the same, so it has to be ONE of you who'll print and process in the same RA4 machine at the same time.
     
  19. Ryuji

    Ryuji Member

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    Before doing such a test, you might want to consult Wilhelm's website. He has done light fading tests on a few common RA-4 papers.
     
  20. Photo Engineer

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    I think it fair to comment on the reported view of one museum curator given me second hand. He felt that digital color prints were archival. Well, so much for that.

    Opinion is opinion, but sometimes even well meaning tests are not very good or very revealing. Kodak, Fuji and Wilhelm differ greatly in the results of their tests. And, you must remember that not one of them is truly objective.

    If they were, then where is image smear publicly reported as part of the continuing comparisions of digital vs analog, and where is the reporting of RC support stability itself? These are two big issues not being properly disseminated. These issues have been tested by all manufacturers and by Wilhelm, but are not front page issues.

    PE
     
  21. Photo Engineer

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    Glass transition temperature of gelatin is raised by adding sorbitol.

    Permeability to oxygen was decreased and scavenging of free radicals was increased.

    Results differ on RC and FB papers due to the permeability of the supports to oxygen, and the inherent ability of FB to absorb more of the sorbitol and change penetration from the back, or support side. This effect is also pH dependant.

    The sorbitol stabilzers could not be used on RC papers very well due to blooming of the sticky sorbitol on the surface of the print. In fact, just about any stabilzer could cause problems when used with RC based color prints.

    This is why the method of glass transition elevation was incorporated into the coating to improve dye stability of later versions of color paper.

    PE
     
  22. Photo Engineer

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    As I have pointed out before, Kodak uses about 200 fc for dye fade and Fuji uses about 500 fc for dye fade. These two tests mimic in one case the average home or museum and the other mimics average office environments. It is, in a sense, a reciprocity condition related to time vs intensity.

    Kodak tested the conditions in thousands of homes across the world to come up with the value of 200 fc, and Fuji has tested many office environments to determine their value.

    The ANSI committee is still out on this subject. Wilhelm uses Fuji's figures for light intensity IIRC. On top of this are the environmental factors of sulfur dioxide gas, and other pollutants that cause dyes to deteriorate. Add on humidity and temperature and experiments become very complex as does interpretation.

    I have even seen a test in which short term stability of prints was worse than long term. The image was recovering with age for a reason that was quickly determined. Even so, this was not desirable, so the problem was solved and the product went out with the fix.

    PE