Carbon print process

Writer / Andrew Glover

How to make a carbon print in one easy lesson!

Always be careful when handling chemicals. Read the health and safety instructions.

So you have looked long and hard for a print medium that will allow you to express every shade and nuance of emotion in your photographic kaleidoscope but you have found none.

Well search no more, this holy grail is no further from you than your nose is to this page.

The most often asked question is what type of negative do I need. Well, any negative that can be printed on a grade 1, 2, 3 or 4 will do. You coud stretch that to O or 5 but that would be exaggerating a bit.

Now to density… if you are like me, and I don’t mean that as an insult, you have been known to squeek your exposures up a little higher than is wise to secure tack sharp twig fips on a day when the wind is about 55mph. Well who can blame you! It took a lot of penny pinching to afford your ‘dagorprotarektarlinse’. Have no fear the carbon process will bail you out of all your photographic sloppiness. Dichromated colloid is all I have to say to you, me lad. This type of process is straight line and has the most obvious effect in the shadows where there appears to have been a large fill card angled perfectly. Lets make a dichromated colloid shall we?

Take one liter of cold water and add about ten tablespoons of knoxs gelatine. Let it sit for around 10 minutes then zap it in the microwave for about 5 minutes on high. Let it sit overnight till it sets and zap it once more in the microwave. This is the basic solution for sizing the final sheet of paper to which your masterpiece will be adhered and the basis for your photographic emusions Get one of those $5 per sheet of watercolor paper from your art supply store, cut it an inch or more larger than your negative and soak it in the warm, not hot, gelatine solution. Hang it up (usually two hours or less) once it’s dry and then repeat twice more. Remember to remove all the bubbles from the side you plan to put your image on. Don’t Worry about the other side.

Contrast is dependant on the amount of pigment in the emulsion. More pigment equals more contrast. Lets say we want to make a nice print of your horrible stepmother or stepfather—well a nice green should do. Take one 7.5ml tube of thalocyanine green and squirt it in a teacup—never to be used for tea again, and add a few drops at a time somewarm water and mix with a spoon so there are no lumps. Add this to your 500ml of remaining gelatine solution and sieve through one of your girlfriend’s stockings, fishnets are hopeless for this purpose while extra support stockings are excellent! Let this cool a little.

In the meantime take a few sheets of hot pressed watercolor paper about two inches larger than each side than your negative. Soak the sheets in cold water. Meanwhile, back at the ranch… you will need a level surface to pour your gelatine ’tissues’. I use a large sheet of plate glass with four balls of modelling clay-one at each corner that will allow you to adjust the level by pressing your weight onto the clay. Don’t press the corner of the glass unsupported by the clay as it will break and cause you and others injury, pop that on top of a table near a sink. Tissue is somewhat of a misnomer, don’t try blowing your nose with this tissue its more like brittle ABS plastic. Take your sheet of hot pressed paper and squeegee onto your level surface. Wipe away any drops of water with a soft cloth.

Then pass your gelatine solution at around 87°F through the stocking and onto the paper. Smooth this out while it’s still warm with a 1″ pipe with some wire wrapped around it to raise the pipe about 1 mm above the paper. Once the gelatine pigment solution is set score out the edges of the paper with the point of a push pin. Lift up one corner with the push pin point and lay it on a sheet of thick cardboard, pin the corners. After a day it will be dry. Oh, did I mention not to allow any bubbles, dust or hair onto the sheet? All will leave a nasty impression on your final print. If you have any streaks in your print, you can blame yourself for sloppy pouring of the gelatine solution.

Once dry, its time to sensitize your tissue. In a liter of cold water dissolve about 3 heaping tablespoons of potassium dichromate. Once it dissolves – and I mean every speck because if you leave one or two they can mess up your print by making that one little speck 10x more sensitive than the surrounding area. Soak your sheet for 3 minutes – when I say soak I don’t mean pop it in the solution and start watching Star Trek again, you have to keep the juice moving over it otherwise you’ll get uneven sensitizing. Which as you can imagine does not look good. Ok, now that its soaked, pin it to the cardboard again and put it in a dark place to dry for about 6-8 hours or so. As the tissue dries it becomes sensitive to light. Did I mention dichromate stains your clothes and can be carcinogenic oops! I forgot.

Now we start the  interesting part. Once the tissue is dry, trim off the rough edges. Use gloves of the cotton or silk variety as your fingerprints will leave marks on the final surface of your print. Cut the sheet to the same size as your negative. Mask off the edge of your negative with some litho tape or mask the outside of the contact print frame. The excess strips from your tissue can be used as test strips. The light I use to expose my negatives is a mercury vapor street lamp. This is a crude but effective method of exposure but for around 40 bucks or less it’s cheap. By the way don’t look at the light since it’s bad for your eyes. Expose the test strip at a distance of 2 feet or so in contact with the negative for about 10 minutes as a starting point.

By now you are thinking this really sounds like a tedious, involved process. Guess what genius—you’re right! This is not for the hobbyist, this process is for the unemployed or
the idle rich. Next we soak the test strip in a tray of cold water for about 5 minutes. While the test strip in the water, slide a plexiglass sheet under the test strip, gelatine side facing the plexi. In one movement, pull both the plexi and test strip out together and squeegee gently. You can get the sheet of plexi from one of the frames stacked in your closet. All right then. Put a sheet of kitchen paper on top of the tissue then another sheet of plexi and then put something that weighs about a couple of pounds on top—a six pack should do. Let this sit for about 7 minutes then we go to the almost last step. In a tray of warm water at around ll0°F, let the tissue/plexi combo sit for a few minutes. When you see gelatine sludge oozing around the edges of the tissue. Gently peel back the paper sheet and rock the tray back and forth to wash off the excess gelatine sitting on top of your test  image. You can put some more hot water in the tray. But don’t make it too hot as this will dissolve away the light tones of the print, you’ll be able to jusdge just how hot a water you can get away with. Once it’s all washed off you can check the density. Take your plexi and turn the gelatine/pigment side to you and lay it face up on a sheet of paper. This gives you a rough idea of how it will look. Remember that the image will dry down by about a stop or so. It’s tricky to say how mnch as each color of pigment dries down a little differently. So now you are in the ball park with your test strip – go ahead and do another or if its close enough go to the big sheet. Expose it etc, etc. etc. Once the image is dry you then take that expensive sheet of paper you soaked in gelatine and soak it in cold water till it’s pliable. Take this sheet and put it bubble free side down in a tray of tepid water. When you start to feel the gelatine getting slimy, slip the acrylic sheet underneath. Pull the plexi and paper out in one movement. Squeegee the excess water out and cover with a sheet of plastic wrap or a plastic trash bag lay another sheet of plexi on top and whatever is left of the six pack when you naively started this project. Let this sit for 1/2 hour. Then peel off the plastic wrap and allow to dry.

The paper will ‘suck’ the gelatine image off the plexi and you have your print. Don’t get impatient at this point! Let it come off the acrylic on its own. If you peel it off you get creases and a ripped emulsion and that will ruin your print and since you’ve gotten this far you may as well go all the way, so slow down! Wow!!!

We’re almost there. Once its dry, soak the print in cold water for 5 minutes. This will get rid of the plexiglass surface on the image and when dry it will have the paper texture instead. You can take out your pencil and sign the print to prove how much free time you have on your hands to do this type of printing or you can go the finishing part which is to soak your print in a 4% formalin solution followed by a 15 minute rinse in cold water. This ensures that if your print ever accidently falls into warm water it won’t melt off the sheet. Formalin is also carcinogenic so make sure your life insurance policy is up to date.

That’s it then—a carbon print in one easy lesson. It took me over two years to make a good one but you are a lot smarter than me so you probably won’t try this process. Which is fine, I am just one of the few chumps who love the scale of the carbon process and won’t settle for anything else as nothing… and I mean nothing looks as stunningly beautiful and rich as a carbon print.

One of the recipes:

A nice standard recipe I used for a long time with good results is the following…

  • 1 liter of 10% gelatine solution
  • 1 Tbspn Carbon Black
  • 7.5ml tube Grumbacher Thio Violet
  • 2 tbspns sugar

Take the sugar and carbon and mix with enough water in a pestle with a mortar till its a creamy consistency, you may have to add a little more water as you go but add by a few drops only. When mixed add the thio violet and mix well, add to the warm gelatine solution and sieve through a stocking-not a fishnet type ;-). Allow to cool and then reheat a few times to drive any air in the solution out and that’s it.

Another useful tip!

carbon printingAfter I make a new emulsion for a series of prints I have a book that I use for my recipes. This book has the ingredients listed and above them is a smear that I made when I dipped my finger in the gelatine solution and spread over the paper. This allows you to see(when dried) how ‘dark’ the shadow tone will be in comparison to the highlights etc. When picking a colour for a print the smear will be an easy to use guide to what you may expect from a print.

Any extra emulsion leftover can be saved in a tupperware tub and frozen for later use (if you don’t plan to print for a while). When you remelt the gelatine be sure not to loose any of the ice crystals in the tub as they are part of the solution and if you throw them out the emulsion will be different in contrast from the time you froze it. Also be careful not to use ice cream tubs as containers, your girlfriend will complain about the horrible tasting ice cream in your freezer and you’ll have to look at a chocolate coloured mouth all night.

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5 thoughts on “Carbon print process”

  1. I am intriqued by Ponting’s carbon prints from the Scott Antarctic Expedition and am going to give one a try. What is the proper strength for a mercury vapor street lamp sufficient to expose a 5×7 contact print? Would a lower wattage simply mean an increase in exposure time?

  2. Hello…. this is a very very complex process. I will definitely have to take a hands on workshop…. the steps are very meticulous, but I would imagine the final product to be sooooo amazing…. I’d like to find a book on this process to obtain a better foundational understanding….lots of work ahead of me! 🙂 thanx again.

  3. Hey there,

    Carbro is indeed difficult, I once heard from a guy who used to make them and he had a lab set up especially for the purpose of making tri-color carbro. He had warm and cool rooms, all the proper chemicals and papers and on a GOOD day he said he could make two prints…something to think about!

    That being said though, it may be easier to scan your chromes in through separation filters then print the image out with pure inks RGB Blk to get the carbro ‘look’, perhaps not the exact same but maybe close enough.

    Another option is to shoot with a Devlin one shot camera and have the three negs already good to go but thats trading another type of hassle as developing the negs is critical.

    Photographing in Color
    Outerbridge, Paul

    This is the definitive book on the subject by the master himself, you rarely see it for less than $100 in good shape. It has tons of info and if you so choose this path there is n better guide, good luck! 🙂


  4. Hello Andrew,
    Thanks for you info thus far. I’m somewhat intrigued by the Carbro process, and would like to know more regarding printing colour prints from colour transparencies. I shoot large-format 6x17cm trannies and have a Durst 5X7 enlarger that may be appropriate for printing the images, but need to know more about printing in colour – I guess four times more complex a process than printing in BW. However, the permanence of the Carbro process does appeal, and I guess it’s exclusivity could asppeal to the photographic collector, so is there a publication that I can source that has all the info that I need?
    Perhaps I should wear a hairshirt and whip myself with barbed wire just to get the full enjoyment of such a laborious process!
    Still, nothing ventured, nothing gained!

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