Hi Bob, I will definitely give this a shot...
Keep in mind, I have actually never made a color carbon print, or even a dye-transfer print, although I speak as an authority on both topics. I'm only an authority in the sense that I'm well read on the topics and am taking steps to make these prints in the future. Plus, they fascinate me! At the moment I kind of consider myself a "pied piper" of these processes and approach them from an academic standpoint. But, photoraphy as art is where my interest lies and where my aims point, and it is with this in mind that I pursue these processes. If only there were more time in the day where I'm not stuck behind a desk...
In mechanics, creating a color carbon print is no different than creating a monochrome carbon print, with the exception of registration. Numerous graphic arts punches have been made throughout the years, and these are all quite expensive. My goal is to use simple office punches, and I have reason to believe that these will be adequate.
The first thing to do is obtain the pigments that are necessary for color reproduction; cyan, magenta and yellow. I got a pint of each of these pigment powders from a place called Lansco Colors, for free as samples.
Here's a post describing the pigments, and here are the ones I got from Lansco. Cyan, Magenta, Yellow. The cyan and magenta are the proper pigments, the yellow was more of an educated guess but I would guess that it should work ok. APUG member mdm has suggested using painter's tints which are conveniently supplied as liquid dispersions.
The tissues are made just like monochrome tissues, but the trick would be in calibrating the 3 colors to create a neutral gray scale when overlayed. Chances are that this would entail a balancing of pigment concentration, gelatin concentration and sensitizer concentration. Furthermore, since carbon relies on UV light and the different colors absorb/reflect this light to different degrees, matching the contrasts is further complicated. This wouldn't be a problem with carbro. Luis Nadeau specifically addresses this and mentions that is most pronounced with cyan.
It sounds daunting, but one place to start would be to make small batches of "glop" containing the 3 pigments at various concentrations. So, let's say you make 10, 20 and 30 (totally arbitrary numbers) grams/liter of each color pigment in 10% gelatin. Now pour these over one another in all the possible combinations. The combination that creates the most neutral gray might be a good place to start regarding pigment concentration. Then, sensitizer affects could be investigated to bring the 3 colors to the proper contrast and scale.
Finding the proper proportions for each color tissue would be the most important and intensive step in a workable color-carbon scheme, methinks. But frankly, it sounds kinda fun!
Now, you need to consider your color separation negatives. This is where my expertise is lacking, but fortunately this is where there is a plethora of information. From classic analog controls via developers and masking to QTR profiles and digital inkjet negatives, there's no shortage of knowledgable people on this topic. Dye-transfer would be a good place to look for sensitometric information and methods for analog separations and masking.
Color corrective masking would be important in an analog scheme and equally important but trivial in terms of effort with digital.
At this point you've got your negatives and your tissues. Assuming double-transfer, you will find yourself with a suitable temporary support be it dichromated albumen coated on mylar (excellent document explaining this on the Yahoo! Carbon Transfer group) or just plain melinex that has been washed and scrubbed with Comet (as per the UltraStable instructions). You'll want to punch this support and you'll need a registration board with pins that matches your punch to hold the temp-support and tissues throughout development. The board might be the only piece of specialized equipment you need, besides maybe a Meyer rod for coating.
Yellow is the most opaque pigment, so this will be transfered to the temporary support last, placing it at the bottom of the final support. There is an excellent video posted by Charles of Tod G. doing this whole process.
This is a pretty basic explanation, and perhaps I've left out some crucial information (?) but in reality I think that anyone could tackle this, and the more people that do it the more the collective knowledge will grow. All we need is a starting point.
Keith Taylor has listed cmy pigments of choice for his process, do you not see them working well with tissue??
I can't find his recommendations; what does he recommend? The impression that Nadeau gives is that the watercolor CMY set is a bit of a compromise; more historical than technical. That's not to say of course that it's incapable of beautiful pictures.
This set listed above (save perhaps for the yellow azo 155), as far as I know, is the best set available today. Keep in mind, I'd love to be wrong and shown a better set. But I know for a fact that the quinacridone 122 is used in UltraStable and Tod Gangler's tissues and I suspect the phtalo blue 15:3 is too. They are highly transparent, light-fast and approximate the ideal minus-red, minus-green & minus-blue complementary colors.
Interestingly enough, Liquitex acrylic Ink! has an ideal CMY set in their catalog. The pigments are listed on the back and they're the same ones from above. I'm curious though if the acrylic nature would make them unsuitable for carbon tissues? It'd be a relatively expensive way to get the pigments though.
Well my question is this,, high quality pigments are used in both processes, carbon and gum, differences in application, but I cannot see any reason why one process would be considered more archival than the other, unless of course if the pigments used in ultrastable are more stable. This is a question I would think worth researching, as there is a lot of research and workers in gum who would say their prints are ever so much archival as Carbon Prints.
Kind of like the who has the bigger one, and I am thinking both processes are as stable as each other , but I certainly do not have this answer and enquiring minds need to know.
I'm pretty certain that they're both completely archival. I would've never thought otherwise; considering that it all comes down to the pigments and the paper.
I think gelatin & gum arabic are like Thelma & Louise.... they'll go out of this life together. . . .:laugh:
I'm just not personally that interested in gum, solely for its look. I can appreciate a good gum print for sure, but it ain't really my bag.
I am thinking the same, but if you ask workers in each process they will swear theirs is better than yours.
when are you coming to Toronto?
btw you just eclipsed me in posts
Hmmm... well they're probably wrong. I'll see if I can't find some hard data on it though.
I'll be in Toronto on the 6th and 7th of October! I'm pretty psyched.
As for my post count, that's an average of 4 per day for the last 2 years! I've been here for 5 years less than you... that's kinda depressing honestly, but I swear I do have a life outside of APUG. In fact, I'm only here while I'm at work, which might make you wonder well what the hell does he do?, but I'm an administrative assistant at a small executive placement firm and I manage to do my work and keep my boss pleased all while studying photography.
What look are you speaking of? Grainy, hazy, unsharp prints?
Originally Posted by holmburgers
Tri-color or full color gums need not look like that. I've seen gum prints that are just as sharp as carbon prints.
Yeah, I guess the "pictorialist" look; to use a worn out term.
This would be an example of a gum print that I really like -> http://www.flickr.com/photos/hansbaz...ceholmburgers/
But in general, the carbon process just seems more versatile and perfect to me. I'm open to the possibilities of gum though.
Gum is just a flexible as carbon if not more so and can be just a sharp if not more so. Tri-Color can be quite stunning as well.
Originally Posted by holmburgers
Take a look at Keith Taylor's work for example.