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  1. #11
    Photo Engineer's Avatar
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    It was pointed out to me that I was not entirely correct in my above post. There were two processes for "carbon color". The colored materials are still produced and AFAIK can still be used for both processes with proper materials and prep. Sorry for any confusion.

    PE

  2. #12
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    Quote Originally Posted by Photo Engineer View Post
    The color carbon was once called Carbro. They still make color pigments for this.

    PE
    Thanks PE I was blanking on Carbo. So if pigments are still made then I assume that someone is still making tri-color carbo. Yes? If not what are the pigs used for.

    Don
    Don Bryant

  3. #13
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    The pigmented glop is used for colored or tinted Carbon printing or full color prints. At least that is my understanding. The Formulary may stock these. I have seen them there.

    PE

  4. #14

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    Quote Originally Posted by holmburgers View Post
    Dye-transfer matrix film is nothing but a carbon tissue with no pigment and the addition of silver-halides... basically.

    Then, thanks to a tanning developer the gelatin hardens in relation to the developed silver in a given area. In this respect, it is just like carbro; a process in which you take a carbon tissue and put it in contact with a typical silver-print (bromide) in the presence of potassium-ferricyanide (off the top of my head). The potassium-dichromate in your gelatin/carbon tissue and the bromide of the print interact and the gelatin is hardened, just as though it was hit with a strong UV light source.

    My point you ask? Well, you'd have to hunt down some old Kodak matrix film or make some of your own to do dye-transfer in this manner. But, a carbon tissue could be exposed in the typical manner, UV, and instead of doing a gelatin transfer, the gelatin could be imbibed with dye to make a sort of rag-tag dye-transfer print.

    Sure, tailor-made matrix films would be luxurious, but would this not be capable of creating a reasonable dye-transfer print? The gelatin relief images could then be re-used in the normal dye-transfer manner, to make any number of prints thereafter. This is the huge advantage of DT over tri-color carbon and the reason why it remained a viable commercial printing technique long after the other "assembly" techniques faded into obscurity.

    I see this as a solution to two problems; 1) the unavailability of dye-transfer materials and 2) the difficulties of making a tri-color carbon/carbro print; which is not as simple as using 3 pigments, due to reflection characteristics and a host of other things... or so I've been told. Plus, the enormous effort to make a one-and-done print.
    Chris,

    You should take a look at the Pinatype Process here:

    http://books.google.com/books?id=REM...page&q&f=false

    If the link does not work then google "British journal of photography, Volume 51; Volume 54" Right after the article on Pinatype is one on Lippman, which is how I found it.

    It is a dye transfer process with what I believe to be plain gelatin plates that are sensitized with a dichromate and exposed in contact with the negative. I was curious about it some time back, but could not find any info or the formulas for the dyes used.

    It seems you could make a plate in the same fashion as you make carbon tissue. However you would need a clear substrate that has been subbed. Then expose from the backside so the hard gelatin is bonded to the substrate. Maybe fixed out Litho film would work.

  5. #15
    Hexavalent's Avatar
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    FWIU, carbro requires a non-supercoated bromide paper, which is a bit of a rarity these days. Monochrome will work with modern papers, but high-quality colour is tricky... not that it will stop me from trying
    - Ian

  6. #16
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    Dongba, thanks for the link to Art & Soul. That seems like some really amazing printing!

    I think that this typifies the current state of carbon; there are a few high-end shops that do it, and individuals who practice it, but largely specific instruction is difficult to find, especially what pigments and where to get them. i don't believe the Formulary has any, nor does Bostick & Sullivan, but I would love to be proven wrong.

    Carbon and carbro are similar in result, but differ in their means, specifically in the way they are tanned. Carbon uses the all familiar reaction of UV-light on dichromated gelatin and carbro uses a lesser known reaction; the tanning action of bromide in contact with dichromated gelatin, in the presence of potassium-ferricyanide. (Hexavelent, good call on the non-coated papers, that makes sense)

    Speaking of which, read the last bit on the Brit. J. Photo. article linked to by R Shaffer about the Pinatype process. It exactly describes this bromide-dichromate reaction, which can be used in lieu of the UV.

    And Robert, thanks for pointing me towards the Pinatype process... that is exactly what I had in mind when I posted this thread, but I didn't even know it! I'm going to look into that more for certain.

    The key will be to find the dyes and if necessary, any mordants. Both fields of which are new thinking to me, so I'll have to do some research. Jim Browning's DT materials .pdf speaks of both, and I know that J.S. Friedman's 'History of Color Photography' does as well.
    If you are the big tree, we are the small axe

  7. #17
    Hexavalent's Avatar
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    IIRC, there are a few chemical variants on the 'tanning' process in carbo: ferricyanide, copper sulphate,manganese, and variations on the 'assemby': ozobrome, carbograph,ozobrome.. and so on. It was everybody's rush to get a patent back in the day!
    - Ian

  8. #18
    holmburgers's Avatar
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    Quote Originally Posted by holmburgers View Post
    So my question is, is gelatin hardened in a tanning developer fundamentally different than gelatin hardened by K-dichromate?
    Seek, and you shall find....

    J.S. Friedman, History of Color Photography, pg. 443
    Quote, "...tanned gelatin has properties identical with light-exposed dichromated gelatin."

  9. #19
    holmburgers's Avatar
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    Ok, it turns out that photo-formuarly does indeed have some dyes. But thanks to their inferior! search functions, they're hard to find. I search "dye" and "acid dye" and nothing comes up. But I accidentally come across Crocien Scarlet and what do you know, the MSDS says that this is also known as Acid Red 66.

    ugh... if that's not shooting yourself in the foot, IDK what is!

    Anyways, they exist and I'll keep searching.

    According to Jim Browning's dye-transfer materials, the dyes we need are:

    Acid Blue 45 (or 25; bluer and transfers slower)
    Acid Red 80 (or 289*)
    Acid Yellow 11 (or 23*)

    *brighter colors at the expense of light-fastness

  10. #20
    Photo Engineer's Avatar
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    The Formulary also has the precolored "Glop".

    I looked up the dyes needed a few days ago and posted them here. I guess everyone missed them. Sorry. Now I don't have the reference handy and it will take me some time to look it up again. Do a search on tartrazine or chicago blue. They may be what I posted.

    PE

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