Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,956   Posts: 1,522,865   Online: 1130
      
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 28

Thread: Fibre RA4

  1. #11
    David A. Goldfarb's Avatar
    Join Date
    Sep 2002
    Location
    Honolulu, Hawai'i
    Shooter
    Large Format
    Posts
    17,161
    Images
    20
    He didn't tell me how long ago he did it, but you can ask him yourself when you're in town for your workshop. You'll certainly meet him.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

  2. #12

    Join Date
    Dec 2004
    Location
    Milwaukee, Wi
    Shooter
    35mm
    Posts
    3,242
    PE I am a bit confused. I thought that James Browning was deceased but that his wife and colleague has continued to work. Ctein expertise has been with Pan matrix film. I know that J&C is selling matrix film but is a panchromatic matrix film available?
    Claire (Ms Anne Thrope is in the darkroom)

  3. #13

    Join Date
    Feb 2006
    Location
    North London
    Shooter
    Holga
    Posts
    59
    Images
    1
    So, PE what you're saying is that FB is unlikely on moderm papers due to BLIX staining and the Daz whiter whites desire. Hrumph Looking pretty bleak at the mo.

  4. #14
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,928
    Images
    65
    Quote Originally Posted by David A. Goldfarb
    He didn't tell me how long ago he did it, but you can ask him yourself when you're in town for your workshop. You'll certainly meet him.
    David, the last FB Kodak color paper was in the 60s. All production ceased after T-1920 paper was introduced. T-1970 and further were all RC and used the blix process.

    PE

  5. #15
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,928
    Images
    65
    Quote Originally Posted by Claire Senft
    PE I am a bit confused. I thought that James Browning was deceased but that his wife and colleague has continued to work. Ctein expertise has been with Pan matrix film. I know that J&C is selling matrix film but is a panchromatic matrix film available?
    EGAD! I've been speaking with a ghost on the phone then.

    Jim is quite alive and well and running a huge photo shop at his business address. You may reach him through his e-mail or web site on the internet.

    He does dye transfer prints from transparencies. He uses matrix film produced using the formula that he has published on the internet.

    PE

  6. #16
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,928
    Images
    65
    Quote Originally Posted by HolgaPhile
    So, PE what you're saying is that FB is unlikely on moderm papers due to BLIX staining and the Daz whiter whites desire. Hrumph Looking pretty bleak at the mo.
    I'm saying that Kodak is unlikely to try this as the dye stability is worse, the staining is slightly higher (IIRC - this was being worked on but was abandoned due to the cessation of FB color products).

    Most importantly, the formula for a FB vs an RC coating is different. Contrary to comments in another thread recently by another individual, the support change introduces a large change in the formula of a paper. RC does not absorb moisture or chemicals, but FB does and therefore there is the requirement for reformulation that goes to David's comment above. Kodak just cannot change support without reformulating, and I know that current paper is not formulated for FB support.

    I have coated Ektacolor 1970 on FB and RC. They were different. This was probably the last paper ever coated on both supports unless it was 1920. This was about 1967 or so. The formulas were quite different as noted above, and ever since, FB was never used as a test bed for color papers.

    Those who are not familiar with coating on different supports tend to trivialize the differences, but I assure you that there are huge variations in support based on paper types and addenda in the papers themselves. This requires reformulation. The same is true if you try to coat a Pt/Pd or Cyanotype on different papers. I've seen problems there as well.

    PE

  7. #17

    Join Date
    Dec 2004
    Location
    Milwaukee, Wi
    Shooter
    35mm
    Posts
    3,242
    Glad am I to hear Mr Browning is alive and well. Thank you for correcting my ignorance.
    Claire (Ms Anne Thrope is in the darkroom)

  8. #18

    Join Date
    Jan 2005
    Location
    Boston, MA
    Shooter
    Multi Format
    Posts
    1,416
    Quote Originally Posted by Photo Engineer
    Most importantly, the formula for a FB vs an RC coating is different. Contrary to comments in another thread recently by another individual, the support change introduces a large change in the formula of a paper. RC does not absorb moisture or chemicals, but FB does and therefore there is the requirement for reformulation that goes to David's comment above. Kodak just cannot change support without reformulating, and I know that current paper is not formulated for FB support.

    I have coated Ektacolor 1970 on FB and RC. They were different. This was probably the last paper ever coated on both supports unless it was 1920. This was about 1967 or so. The formulas were quite different as noted above, and ever since, FB was never used as a test bed for color papers.

    Those who are not familiar with coating on different supports tend to trivialize the differences, but I assure you that there are huge variations in support based on paper types and addenda in the papers themselves. This requires reformulation. The same is true if you try to coat a Pt/Pd or Cyanotype on different papers. I've seen problems there as well.
    Ron, are you distorting my postings again?

    It is obvious that in color printing materials the emulsions have to be reformulated to accommodate the difference between the support materials. This is very different from the case of you coating primitive b&w emulsion on various fiber paper bases. The major difference on the emulsion side comes in the consideration of tonality, color saturation and neutrality of gray.

    The scattering of light by the whitener affects the selection of suitable filtering dyes added to each layers. Also in the case of baryta there is some chemical diffusion into the base and will decrease the efficiency of coupler reaction in the lowermost layer. There are several additional considerations in the color material.

    Change of the bleaching agent from ferricyanide to iron aminopolycarboxylate complex is one thing. I think this happened well before the RA-4 process.

    In 1960s the color papers were still containing high molar fractions of AgBr and the order of layers may be different from the RA-4 era. Ektacolor 2001 and subsequent AgCl-based RA-4 papers also changed the stories again. The red- and green-sensitive layers are much less sensitive to blue light than before and so the blue-sensitive layer is usually coated first (botom). Thus reflection of blue light by the support is a part of the emulsion design. It's obvious that the emulsion has to be redesigned if the support material is changed.

    But these are an aspect of multilayer color materials and their processing chemistry, and so they are at a completely different level from your primitive b&w emulsions.

    I coat my emulsions on various fiber papers, plastic films and glass plates, all at coating speed lower than 10m/min, but difference among paper substrates is easily absorbed by applying a custom subbing layer before coating the emulsion. Even then, the role of subbing layer is concerned about mechanical strength and adhesion, and not about the emulsion property. Depending on the difference in the substrate and the whitener (among reflection materials---transparency is a different story), I see some small difference in the sensitometric curves, but that's well within what I can tolerate. Also, I can change the curve by changing the pAg of the growth stage, blending proportions, or often simply by changing the coating weight, if I really want to, but that's not necessary. I think you are overcomplicating the issue when simpler solutions are already worked out.

  9. #19
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    22,928
    Images
    65
    Two weeks ago Friday, I demonstrated my coating method for a member of the faculty, who is a conservator for George Eastman House. This was done in my darkroom here at home.

    The demonstration included coating the exact same emulsion formula on two different fibre based supports. He was able to observe first hand that the coating went well on one support but repelled heavily on the other, leaving large gaping spots.

    We allowed the prints to dry and had lunch together, and then went back to the darkroom and processed them so he could again observe them in the light. That next week, I brought the prints to GEH so he and I could share them with another member of the faculty and discuss this very observation. Support changes can require reformulation of a coating with respect to surfactant or require other changes to allow for a smooth coating.

    Ryuji has made a statement. It may indeed be the case for him, but I object strongly to his criticizing my work and saying that I am wrong. I make no comment about his work, merely that I have had to reformulate coatings here at home and at Kodak due to support changes.

    I daresay that I have probably made more hand coatings in a week than he has made in his entire life. These were both color and B&W. My formulas are and were adjusted to coat well, not to satisfy some abstract need to be identical. This is, in large part art. What works for you may not work for me and etc.... Therefore, his observations and mine may differ but that does not need an element of criticism to enter into it.

    In a typical evening at home, I coat about 15 sheets of 11x14 paper with a good surface area of 8x10. I find that even going from 4x5 to 8x10 on one single paper will change the required surfactant level to get an optimum coating even with all other aspects kept constant.

    Having performed this demonstration to other individuals I feel that I can rest the case. I do not call Ryuji's results into question at all. Differences exist between methodologies, paper size, temperature and etc. The also differ between emulsion types. I have learned this through years and years of experience.

    Ryuji does not seem to accept the fact that things differ. He even implies that I'm in error. My results have been demonstrated for several GEH faculty members and for fellow Kodak engineers. They all are aware of similar problems in developing this art form for the darkroom enthusiast.

    At the present time, a series of workshops are being conducted at GEH under a grant from Mellon Institute. GEH has purchased one of my coating blades and this blade, a prototype, was delivered last week. Next week, I hope to be showing the instructor how to use it in his course for coating prints on a variety of FB papers.

    Sorry to get so far off-topic, but this continual innuendo by Ryuji that I don't know what I'm talking about is getting to me. I apologize to the readers, but I felt that this response was needed. His work is just fine, from what I have seen. I have no criticism of it. I have posted some of my prints on this site in other threads for you to judge my results as well.

    PE

  10. #20

    Join Date
    Jan 2005
    Location
    Boston, MA
    Shooter
    Multi Format
    Posts
    1,416
    See, this is typical Ron in switching the issues and he has to be right at the end. We've seen enough of this.

    Anyway, what you are talking about is coating defect, which is a mechanical issue related to spread and adhesion. A change in surfactant is not really a reformulation of emulsion. What an exeggeration!

    On the other hand, the reason why the emulsion system has to be redesigned in color paper has more to do with chemical and optical properties of the substrate. That's my point in the previous post. Where did I criticize your work? What's discussed above are concerned about color material and your current work is b&w. There is nothing to criticize here, besides your fallacious reference to my post in another thread.

Page 2 of 3 FirstFirst 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin