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  1. #61
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    And Sandy, don't forget that I could make my own film and paper from scratch which was a real treat. That really killed me on DT. Too hard and expensive. It was a product and wasn't being messed with, but Ektacolor paper and Kodacolor film were being actively researched.

    What fun. I just took a walk and was remembering those days fondly, especially with 9 and 23 coming down.

    PE

  2. #62

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    Quote Originally Posted by Photo Engineer View Post
    And Sandy, don't forget that I could make my own film and paper from scratch which was a real treat. That really killed me on DT. Too hard and expensive. It was a product and wasn't being messed with, but Ektacolor paper and Kodacolor film were being actively researched.

    What fun. I just took a walk and was remembering those days fondly, especially with 9 and 23 coming down.

    PE
    Ron,

    What is 9 and 23?

    BTW, I may have misunderstood Z-Man, but my point about color carbon is that it is so terribly complicated to begin with that anyone seriously thinking about becoming a master printer is not going to be concerned about whether he/she uses digital or analog negatives. One already has to make from scratch virtually everything that goes into the process, i.e. the tissue, final supports, temporary supports, etc. All of the persons I would consider master color carbon printers today are working with imagesetter negatives. I am not sure about Mac McCowan. I have known (over the phone and via email) Mac for a very long time and I believe he works with analog negatives since he prints mostly carbro, and mostly monochrome for that matter.

    There was a very good color carbon printer named Renee Pauli who worked with analog separations, but he died about ten years ago before the use of digital was widely used.

    I personally would like to see the working procedures for all historical color processes preserved, and that definitely includes making color carbon and carbro since these were the very first processes used to make color prints on paper. But speaking as a person who has actually done this I can tell you that it is very complicated to get it right. You mentioned that DT was difficult. Well, most people would recognize that compared to color carbon DT is a walk in the park in the spring.

    Sandy King

  3. #63
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    Sandy;

    In another thread there is a discussion about Kodak imploding two venerable buildings at Kodak Park, namely B9 and B23. Very sad. I was thinking about the times I spent there. I remembered that the main Kodak analog computer was located in B23 and I took a course in programming it there. That was interesting.

    As for the rest, remember that we discussed color carbon and carbro last year at the Formulary. There were pigments there at the time, but we only coated the black carbon glop together. I agree, they are wonderful systems that should be preserved. I also loved the look of color bromoil transfers.

    All of this is hard to learn and takes days to produce one good print. After that though, as long as you keep your DT matrices in good condition, you can crank out dozens of DT prints / night. But getting to that point requires lots of practice.

    The same is true in emulsion making and coating. It is an artform in itself that has to be mastered. And it varies from location to location in very subtle ways.

    PE
    Last edited by Photo Engineer; 06-30-2007 at 10:43 AM. Click to view previous post history. Reason: phrasing

  4. #64

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    A response

    I've been locked out of this thread since soon after my last post a couple of days ago, because I accidentally clicked on "ignore thread" when I meant to click on "ignore user." (I don't choose to continue reading posts from persons whose purpose seems to be to insult and inflame, rather than to have a dialogue with fellow forum members). But since a few reasonable people here seem to be taking this troll seriously, I think it's only fair that I should correct some of the more inaccurate pronouncements that were hurled in my direction, and since the software is suddenly allowing me into the "post reply" page for the thread, I shall try to do so as briefly as possible, just addressing the more important points that still stick in my mind from a couple of days ago and letting the sillier ones go:

    1. Repeatability: Somehow it was believed that I had said that tricolor gum, or maybe just my tricolor process in particular, is not controllable or repeatable. I never said that; it's not so.

    2. Accurate colors with tricolor gum: I wrote that with tricolor gum it is easy to make a color print in which the colors are read as "accurate enough" by the mind, but difficult to make a color print in which every color in the original is exactly and precisely replicated in the print. This is even more true of cmyk reproduction than of tricolor gum, so the advice to go to cmyk printing for answers doesn't provide any useful solution. As most of us know, there are many colors that can't be printed in a standard cmyk printing, because they are "out of gamut." The cmyk reproduction is read by the mind as a fairly accurate representation of the colors in the original, but all you have to do to see how far off it is, is to put the original up next to the reproduction. When I spoke of it being difficult to reproduce every color precisely in tricolor gum, I was talking about levels of accuracy way beyond what the usual cmyk reproduction is capable of. z-man recommended following the press practice of making as many as ten negatives (and ten press runs) to achieve accurate colors. I could be wrong, but I doubt there are many publishers of books and posters who could afford all those press runs, and at any rate, in tricolor gum you could probably do it with two more colors beyond the original three (making it hexacolor gum rather than tricolor gum) if someone wanted to be that precise about replicating every color exactly accurately.

    3. Confusing RGB with CMYK: This is something I've never done. Perhaps the listing on my table of contents, "How RGB channels become CMY separations when inverted" may have been misinterpreted by someone determined to misinterpret, but if a person had actually clicked on that link and followed the numbers, you would see exactly how it works. As anyone knows who has ever printed color photographs in the darkroom (or adjusted color curves in photoshop), RGB and CMY exist in a complementary relationship with each other. The more red, the less cyan and vice versa. The same with the blue-yellow continuum and the green-magenta continuum. When RGB channels are inverted, they become negatives that accurately print CMY. People don't believe that until they follow the numbers through, (or just print the separations) but it's true. But to point out that observable fact is hardly to confuse RGB with CMY.

    4. Photoflood: I was treated to a hail of ridicule because I print with a photoflood bulb. z-man made a point of saying, as a way of insulting me, that he can read, but he apparently didn't read my page on why I use the photoflood. I don't use the photoflood because I'm too stupid to know any better, but because it has proved to be a very good light for printing gum. I started out with it because it was a cheap and easy light source, and I wasn't sure before starting that I was going to stick with gum, so I didn't want to invest a lot of money into startup. That was more than 20 years ago, and I still don't see any reason to use anything else.

    Among the many contemptuous remarks that were made on this subject, it was said that if I would get some other light, my printing times would be more like 10-15 minutes. Why would I want printing times of 10-15 minutes, when my printing times with the photoflood are 2-5 minutes? And as for the spectrum, there's very little known about the actual spectral sensitivity of different dichromated colloid emulsions. The conventional wisdom is that their sensitivities are all the same, because it's assumed that it's the dichromate that determines the spectral sensitivity. But when the spectral sensitivity of various dichromated emulsions has actually been compared, it's been shown that they aren't the same, that the colloid itself has a significant effect on the spectral sensitivity, and that the spectral sensitivity of gum is more in the visible range than in the uv range. So for gum, it may not matter that there's not much uv from the photoflood.

    At any rate, I've always believed in letting the gum decide; in other words, I prefer to let observation rather than theory (or ridicule!) drive my decisions, and the photoflood works very well for gum. I don't have a lot of the problems that many other gum printers report (dichromate stain, tonal inversions, low contrast etc) and I suspect that the reason for that may be the light source I use.

    5. Pigments. It was said that I should order yellow, cyan and magenta process paints from Jerry's Art-O-Rama rather than using the more lightfast pigments that are available in good artist's lines. Daniel Smith (my art supplier) doesn't even carry such process paints, and if they did, I wouldn't buy them. Generally speaking, such process paints are made of inferior pigments and aren't lightfast, and besides, there are pigments available that are close enough to true yellow, cyan and magenta, that they serve quite well, even if they fail to satisfy the literal-minded by going by those exact names.

    __________________________________________________ _____________
    Additional thoughts in response to comments by PE (since I don't trust the system to let me reply more than once to a thread that I've clicked "ignore thread" for, I'll put all my responses here):

    Yes, I agree that you have to look at the colors as well as whether the three colors produce neutral greys, but you have to start somewhere. Once you've got a neutral grey when the three colors are overlaid, then you can proceed to determining how well a combination of pigments reproduces individual colors, or color ranges. Generally, in my experience, if a combination of pigments reproduces green well, then it won't do so well with the purples, and so on, and that's why it may be necessary to introduce some secondary colors for precisely accurate color reproduction, as recommended by Bruce MacEvoy, the man I consult for expertise on pigments.

    You mentioned that you were surprised at how a CMYK print with the K layer left off looks, but it shouldn't be surprising because it's a function of the separations and of the printing inks. Since, as I explained in the page I referred to earlier in this thread, the color information is altered to accommodate the black and the limitations of the printing inks, the CMY parts of a CMYK file aren't the same as a true CMY file generated by inverting the RGB file. Gum printers sometimes make this mistake, thinking that by choosing CMYK in photoshop and not using the K printer, they are getting true CMY separations, and are surprised at how wimpy and offcolor the result is. I don't know, but strongly suspect, that that's what's wrong with the tricolor gum prints on one of the links supplied way way earlier in this thread, where CMY is compared to CMYK: the CMY prints look very strange,, probably because the CMY prints aren't the result of a straightforward conversion to CMY, but are the CMY portion of (default) photoshop CMYK, which is a horse of a different color altogether.

    Your point about the density required for true black is well taken.

    Thanks for the opportunity to respond; as far as I know the thread is still unavailable to me so I won't be participating further, but just wanted to clear up some of the misconceptions I did see before I locked myself out of the thread.
    Katharine

  5. #65

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    THANKS FOR THE MEMORIES

    [QUOTE=Photo Engineer;486628]Sandy;

    In another thread there is a discussion about Kodak imploding two venerable buildings at Kodak Park, namely B9 and B23. Very sad. I was thinking about the times I spent there. I remembered that the main Kodak analog computer was located in B23 and I took a course in programming it there. That was interesting.

    As for the rest, remember that we discussed color carbon and carbro last year at the Formulary. There were pigments there at the time, but we only coated the black carbon glop together. I agree, they are wonderful systems that should be preserved. I also loved the look of color bromoil transfers.

    All of this is hard to learn and takes days to produce one good print. After that though, as long as you keep your DT matrices in good condition, you can crank out dozens of DT prints / night. But getting to that point requires lots of practice.

    pe-you are a great treasure to all of us here

    in the 50+yrs i have been paying income tax on the money i earned as an artist(yeah i started paying when i was 12) i also have seen to much of what was good go down the pipe-but we still have our memories to gladen our hearts

    i don't know why every one thinks it is necessary to totaly roll your own in the carbon process tho

    the co who started it all autochrome still makes tissue-only one color tho

    i prefer the "ultrastable" system-it is quick, repeatable and gives completely photo realistic 4/c if you use it as designed-i of course have never left it at that as soon as i have mastered any system

    pe-thanks for your detailed answers to my questions-i never did the actual dt myself-only watched out of curiousity-to picky a process for my lazy self-but you actually stuck it out and that is a testiment to your own self-respect

    you want a picky/cranky/tedious process?-try makeing a chromalin-pe i know you have seen the finished product-any comments on that one?

    vaya con dios

  6. #66
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    Z-man; I've never heard of chromalin or if I have I've forgotten. Thanks for your comments. Keep up the good work.

    Katharine; It would be straightforward to determine spectral sensitivities of any light sensitive system should you wish to devote the time to it. A simple monochromator with a step wedge will do the job. I have posted several samples here on APUG.

    As for my being surprised that you refer to, that refers to the fact that some systems need CMYK and others only need CMY and it is not obvious to a casual observer or inexperienced person which systems or dyes do and which do not. It is also not obvious why these differences exist. It took some training and experimentation for me to understand it lo these many years ago.

    And, as for green vs purple color reproduction, this is not always the case. It is a function of color masking (or lack thereof) which can lead to the problem due to the dyes chosen. I have seen this as well, but simple substitution of the dyes has usually solved the problem. OTOH, it may be as simple as the peak absorption of the dye or the half bandwidth of the dye being wrong for the print material, but the effort to fix the problem can be done either by measurement (which I did) or by trial and error which is tedious.

    Of course, I had the advantage of one of the world's largest libraries of dye forming materials to choose from along with the curves they produce and the math models with which to work to make the selection.

    I may have prints here that illustrate this. We did a coating series with different dye formers to establish just about what you describe, and I remember bringing several of the prints home when the project was finished. If I find them and can scan them in with good results, I'll post them.

    PE

  7. #67

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    Quote Originally Posted by z-man View Post
    \
    i don't know why every one thinks it is necessary to totaly roll your own in the carbon process tho

    the co who started it all autochrome still makes tissue-only one color tho

    i prefer the "ultrastable" system-it is quick, repeatable and gives completely photo realistic 4/c if you use it as designed-i of course have never left it at that as soon as i have mastered any system
    The only carbon tissue made by Autotype is the blood-red color intended for photogravure. If you like the color, ok, but I personally find that color very unappealing.

    Ultrastable ceased manufacture of color carbon tissue several years ago.

    At this time there is no production anywhere in the world of color carbon tissue. That may change soon as B&S has announced they plan to make the material. But not available as of now.

    Sandy
    Last edited by sanking; 06-30-2007 at 12:18 PM. Click to view previous post history.

  8. #68

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    THANKS FOR THE HEADS UP RE ULTR. . .

    Quote Originally Posted by sanking View Post
    The only carbon tissue made by Autotype is the blood-red color intended for photogravure. If you like the color, ok, but I personally find that color very unappealing.

    Ultrastable ceased manufacture of color carbon tissue several years ago.

    At this time there is no production anywhere in the world of color carbon tissue. That may change soon as B&S has announced they plan to make the material. But not available as of now.

    Sandy
    SANDY-

    personal medical crisis after crisis for the past 3 yrs has put me totally out of the loop

    i was just looking for the last paper work so i could re-up on ultra --silly me-like the sticker shock when my refrigerator came up empty re 4x5 polariod and i went to b&h to get a few boxes-almost had heart attack #3

    silverprint can't or won't ship the autochrome tissue they stock out side of the eu but i have workarounds if i want some-as you say the color as supplyed is not for everyone but i can modify it somewhat

    my main concern these days are the hazmat issues of pigments-the massive neuro damage i have has been characterized , by a few world class nuerologists, as heavy metal and other non-organic poisoning-maybe swimming in artists materials and photo chemicals since the age of 7 is the cause-the drs are still debating this

    because of this i will start using the lascaux "sirious primary system" -i can get other cymk water color pigments but the toxicity issues are not as transparent(ha ha)

    am currently overprinting tea stained cyano with an emulsion colored with beet juice-the resulting 3/c is of course surreal

    my attempts to put on top a yelo pigmented with tumeric have not yet been as happy as i want

    any input on this 'green' issue would be of great help

    PE- will tell you about Dupont's chromolin process another time-gotta eat more morphine right now

    vaya con dios

  9. #69

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    Quote Originally Posted by z-man View Post
    SANDY-

    personal medical crisis after crisis for the past 3 yrs has put me totally out of the loop

    i was just looking for the last paper work so i could re-up on ultra --silly me-like the sticker shock when my refrigerator came up empty re 4x5 polariod and i went to b&h to get a few boxes-almost had heart attack #3
    Hi Z-Man,

    I wish you well in recovering from what hopefully is a "temporary medical crisis."

    Fortunately my state is still such that a good dose (or three-six) of reposado Tequila numbs the sense enough to carry on.

    My very best to you,

    Sandy
    Last edited by sanking; 06-30-2007 at 11:02 PM. Click to view previous post history.

  10. #70

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    dupont cromolins

    Quote Originally Posted by Photo Engineer View Post
    Z-man; I've never heard of chromalin or if I have I've forgotten. Thanks for your comments. Keep up the good work.

    PE
    pe-
    chromolins are(were?) the best color break that could be made at the time. dupont updated the dusting on process with modern technology. a sticky emulsion would be burned with a color sep and then a very pure hue powder pigment would be dusted on, a layer of the unpigmented emulsion would be burnished down and then each each sep would be burned untill the color break was complete and a final layer of the emulsion-it is in a film form-would be put on to cover it and then given a burn without a neg/or/pos and no dust on of pigment, to seal the whole composit and give an even glossy surface

    if the break was a simple 4/c of a 35 mm chrome the result , with a high # screen, was breath taking and, sometimes , at lets say 24x36, it would be better looking than the original, and unless you used a 10 power loupe , the screen ruling was lost in the mix. it looked someting like a ciba , and with the benefits of all the tonal compression done during the separation process the contrast was completely tamed- you had a color print that looked like the chrome

    the purpose was to get a preview of a high count screen on best quality coated stock coming out of a sheet fed-a pre press proof of a press proof for coffee table books etc

    the room was dedicated, sealed, and forced ventilation and personal ventilators and masks like a scuba divers were necessary. the tech did nothing else and the learning curve was considerable

    i was getting my certification for 4/c stripping and the school was at a high cost prep house-i talked the tech into getting me started, but my tuition was payed for by the feds
    and the stripping , plate making, camera, drum scan and vacume frame classes were all that could be billed-the cost of a chromolin was more than a dt if i remember right and i ran out of funds for the chromolin materials-sound familiar?

    i learmed enuf to know that i had to home brew an equivelent-but never was able to get all the way to 4/c- i did confirm that i could work with continous tone separations and my training at a culinary arts high school gave me the ability to work with sugar without burning myself to death-the sugar chefs courses were mostly women when i was in that school so of course i hung around them like the dog i naturally was and obsorbed the techmiques while other things were on my mind

    sandy-the medicinal benefits of mescal and the intoxication from the aroma of the fields even before the 'pinas' are harvested are blessings of the creator in my opinon- inshAllah i may have the opurtunity to thank you for the blessings of your good will-i told gadjet i would celebrate his birthday, and i owe a childhood friend transplanted to nc a visit- might get a chance to buy you a round

    vaya con dios

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