Reading over the tissue making part, I may have given the impression that time is the overarching expense of this process. Nothing I say in part 2 will dispel that notion. Carbon tissue is a very inexpensive process as far as material costs go, but the overall investment of time can feel a bit conspicuous.
I may have also given the impression that this is more superstition that science. Hereafter, I’ll tag all of the “questionable guesses at best, but probably bullshit” remarks with an asterisk*.
Keeping in mind that some of the following was also listed in part 1, here are the principal bits for the printing steps. Unless otherwise noted, the sources were provided in part 1. And a reminder about units: I try to use metric whenever possible, except for imperial format sizes like the film formats for large format photography, or if a material source uses imperial in their product description.
- Tissues from part 1
- Negative, digital or in-camera
- .002″ optic-quality Mylar
- Final paper support, previously gelatin-sized and hardened water color paper
- UV light source
- Print frame
- 20% Ammonium dichromate solution, in eye dropper bottle
- 70% isopropyl alcohol (acetone is also a good sensitizer solvent, but I vastly prefer the odor of alcohol)
- Plastic print trays (less conductive than stainless steel or enamel)
- graduate, 100 ml range
- 90mm Foam brush
- Squeegees, wide one for sensitizing, short one for transferring.
- Work surface, and a reliable way to contain the effluents
- Rubber chemical-resistant gloves, apron, and various PPE to taste
- Rags for clean up
- Flat water*. I keep a stock of flat water by replenishing distilled water jugs with tap water, and leaving the cap off for several weeks.
- Dry mount press, or clothes iron and museum board for flattening prints
I make sure everything is tidy and setup before dragging out the chemicals. I set up a elevated 30x40cm tray for the mating bath, and add 1 gallon of flat water to it. This water should be cool so it doesn’t start to melt the gelatin before the mating can take place. (I’m no longer convinced that the water needs to be flat, but as bubbles are the bane of carbon printing, it helps to avoid effervescence whenever possible.) I keep it elevated so the dumping all the hot development water doesn’t raise the bath’s temperature. If it’s a hot day, then a supply of ice cubes to cool the bath is helpful*.
Then I set up the work surface for sensitizing and squeegeeing the “mate” together (the assembly of exposed tissue and final paper support). This doesn’t need to be dead level like for the tissue pour, but if it does slope, make sure downhill is aimed towards a sink or container so the sensitizer doesn’t run wild.
I also get out a piece of dedicated foam board that I will pin the sensitized tissue to, and have the pins ready. While the sensitized tissues aren’t really prone to fogging under typical room light, I usually hang a hotel drape in the window to be on the safe side. In that spirit of overkill, I also have a little makeshift foam board lean-to to block out extra light while the sensitized tissues are drying, which can take an hour or so. A fan speed the process of drying, but I usually wait an hour after sensitizing, to ensure that the tissue has cured completely.
I also trim the tissue. Not to final print size, but simply to cut away the long edges of the tissue so any rough edges wont make the squeegee jump or snag, leaving puddles of sensitizer behind. Then I get out the dichromate, brush, graduate and squeegee. I get a damp rag ready for wipe down the tissue margins after brushing (or any accidental spills).
The main idea is to get everything ready so you don’t have to touch (and contaminate) a bunch of stuff with the dichromate-tainted rubber gloves. I usually go through the steps in my head to make sure I can complete the sensitizing and put the tissue away for drying without removing the gloves and without touching anything I can’t easily clean. Anything that cannot be easily cleaned of dichromate residue should be labeled that this is what it is used for, and stored in a place for such items.
That done, the gloves are on! I dilute 50 drops of the 20% dichromate in 50ml of 70% isopropyl. (I like this ratio of 1 drop per 1ml, it’s easy to remember and adjust the volume for tissue size. I calibrate my negatives to this ratio.) With the timer set for 2.5 minutes, I dump the solution onto the tissue and brush for 2 minutes, spreading it out quickly and evenly. For the last 30 seconds I squeegee the tissue, pulling the waste into a tray in the sink for disposal. I try not to leave streaks or puddles, which may cause irregular sensitivity * . With the dampened rag, I wipe away the bare margins of the Yupo, so drips won’t run back down the surface when it’s hung to dry. Then I hang it over the sink to wipe down the back to clean off any messes before moving outside the sink area. Then, it’s pinned to the foam board and set in the “drying shack” to cure for an hour. While the alcohol dichromate solution does evaporate quickly, I give it at least an hour to make sure it is thoroughly dry. Meanwhile, I wash everything thoroughly and then get the negatives ready.
The negatives are printed using an Epson 3800 and QTR. As digital negatives is a fairly large subject in itself, I won’t go into that here. But here is the profile I made, which is matched for the tissues, sensitizer strength and the light source I use. Carbon_181340_crved .
I let digital negatives cure at least for 24 hours, otherwise the inks will stick to the mylar and the negatives are spoiled. I print a 10mm safe-edge around the border of the negative. This gives a clean border to the print without having to use rubylith to mask the borders.
Now the tissue are trimmed to size, a little under the dimensions of the negative including the borders. The tissue is taped to a backing board, piece of very thin but rigid plastic sheeting (found in the quilting section at Joanne’s). This backer helps prevent the texture from the vacuum bed from transferring to the tissue. Over that goes the mylar interleaf, with is taped down to the backing sheet to secure it. Then finally the negative is carefully positioned and taped to the Mylar. This sandwich is loading into the printing frame, in my case a vacuum easel, and the vacuum is turned on and checked for proper draw. Note- if the vacuum is set too high, the tissue surface can get burnished, but this also may be related to the moisture content of the cured tissue*.
My bank of UV lamps are about 70mm from the surface of the print, so exposure takes about 23 minutes. The lamps get warm. I have an internal fan in the printer, but if it’s a hot day I’ll point a supplemental fan at the unit to help keep it cool. While it’s exposing, I’ll write details on the back of the paper support I’ll be transferring the exposed tissue onto, the previously sized Lana watercolor paper. Date of printing, date of tissue batch, negative profile, sensitizer strength, and length of exposure. Even though some of these details never seem to change, it’s good to have to confirmation notes on the print itself when delving into a pile of old prints. But since I write a brief log for each and every printing session to note any oddities or new experiments, the date alone would probably be reference enough.
After the exposure, the tissue is placed in the mating bath. 4-5 minutes in the bath. The tissue will start to reconstitute slightly, feel almost imperceptibly slimy and swollen. I should be wearing gloves to do this, but I like the tactile experience. For the last 45 seconds to one minute the watercolor paper is placed in the bath, and mated with the tissue. The idea is to reactivate the gelatin in the tissue and the sizing enough so it can form a mechanical, protein-level bond together.
In a quick motion, they are pulled from the bath together and placed on the slab and squeegeed. It will want to slip around at first, but will get increasingly stuck with progressive squeegeeing. I turn the assembly often to be able to squeegee in each direction, then leave it to mate for 20-30 minutes. With a really good bond, the sandwich will start to curl up. The temptation when first starting out in carbon is to pile a bunch of books or bricks on it or use a lot of force when squeegeeing to increase the chances of a good bond, but that’s really not necessary.
After the timer sounds, place the sandwich in a tray of 40-45C water. You’ll see tendrils of ink after a moment and it’s generally safe to start pulling the backing away after a minute. There should be little or no resistance. If it feels stuck, give it more time. Once the Yupo is off, I flip the print over and develop face down in the hot water, sometimes covering the tray with a synthetic cutting board to keep the water warm for as long as possible. This is only one of the many reasons I really like 90lb/185 GSM Lana watercolor paper: it floats, and there’s no risk of the print settling to the bottom of the tray and getting damaged, and by floating upside-down the melt just settles to the bottom of the tray so the print develops more quickly.
I pretty much develop to completion- it stays in hot water until no more ink drains off when lifted from the hot water. This way I’m sure I have actual exposed highlights, and not just staining. This takes about 10-15 minutes, depending on water temp and other factors. After development, I’ll rinse the print briefly in cool water to help set the gelatin, then hang to dry. It’s worth noting that there’s quite a bit of drydown in both the shadows and highlights in carbon. The blacks look a little weak and cloudy, and the extreme highlights can look blown out, but it dries down just right. It took me a while to get used to the effect.
Since tweaking this method to this current state I’ve enjoyed a 100% transfer rate. No frilling, bubbles, or other failures. I can’t remember the last time I had a bad transfer. Some of the steps above may be questionable, or superfluous, but if it ain’t broke…
The day after…Wrinkled, curled, awful. Having a dry mount press really helps with flattening prints, but some cardstock and a clothes iron will also work well. Flattened, crisp, with shadow depth to strain oblivion, the print emerges, and suddenly there’s nothing quite like a carbon print. So much so I hesitate to even post scans of the prints here, because they really lose just about everything that makes them special in the translation. And then, if the scans aren’t already bad enough, WordPress’s crappy compression defaults pile on top…woof. It makes it almost embarrassing to share my enthusiasm for the process with the world at large, or to convince distant friends and relations that I’m spending my time wisely.
But whatever. It’s too much fun to worry about that. Here are a few more from yesterday-
