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Color: Capstaff Meets Bi-pack

January 26, 2014

I'll spare myself all the scanning, and you all the viewing, and just narrate the color progress so far. I have been unable to come up with an acceptable (to me) arrangement for tri-packs. With all the ways I've tried, the resolution of the back sheet of film (the panchromatic/red) layer is mush by the time the light has passed through two other layers of film with emulsion in addition to a yellow and a red filter. I flipped a coin to decide which direction to follow. Should I keep plugging away at the tri-pack or go back a step to something simpler? Simple won the toss. Bi-pack it is.

BI-PACK. A bi-pack is very simple — two pieces of film loaded emulsion sides together in tight contact. The devil is in the details, of course. It's amazing how many combinations are possible with only a handful of variables! I think I tried them all before I came up with what I think is a good starting point for the next step — color. Bi-packs aren't able to deliver true color. That requires three color layers. But, two layers have creative potential and there is always the separate exposures/three-color separation technique when true color is required.

The first step, before color balance can be considered, is working out the density balance. The b&w positives made from the bi-pack negatives are the components of the final image — a variant on the CMYK model, with 'K' being the shades of gray from black to white. If that range of values doesn't come close to what our eyes perceive as reality the image fails.

Above: The Lightroom interpretation of the GreMac chart as a b&w negative (color file made with a Sony Cyber-shot RX100.)

Left: Two bi-pack negatives in registration, and below, a 0.5 x 0.2 inch crop, inverted.

I don't think it would have taken me so long to figure out this step if I hadn't been so wedded to the idea that I absolutely must use my gorgeous handmade yellow and red gelatin filters :-) There's probably a whole PhD dissertation on 'stuck-headedness' in there somewhere. It wasn't hard to admit that the filters contributed to mushy resolution, but I really thought some filtration had to be necessary for density/color balance. Turns out not to be the case. (At least that's my interpretation at this point in the game. Could still turn out I'm dead wrong.) The two layers are 'AmBr-Ortho' and 'AmBr-Pan', exposed without a filter.

* The Light Farm tutorial workshops teach making an emulsion, including my 'AmBr' series, (Amber-colorblind, -ortho, and -pan) from start to finish. They are free and linked from the homepage.

THE CAPSTAFF PROCESS. In 1914, John Capstaff, working at Kodak Labs, devised a two-negative color system. Originally, it involved two dry plates exposed in a beam-splitter camera with green and orange-red filters. The negatives were made into positives, which were dyed the same colors as the filters and then sandwiched together for viewing as a transparency — a color slide considered by historians to be the first Kodachrome. The process moved from beam-splitter to bi-pack and then to monopack (everything coated on a single piece of film). Some writers call this an 'integrated bi-pack'. When the process added a third color layer, true Kodachrome was born.

I am delighted to stick with Capstaff and adapt the process as best I can. The palette is actually very appealing. Fingers crossed that I can come close. Here's a link to more information.

And a lovely thing here.

TECH UPDATE: A Better Way to Sensitize Panchromatic Film

To recap: Handmade panchromatic film is made by bathing sheets of ortho film in a dilute dye solution (in this case, 1% pinacyanol chloride in methanol, diluted further in distilled water) and then re-drying the film. The amount of dye and the amount of time soaking are the variables.

An emulsion can be made orthochromatic by adding erythrosin during precipitation. Since orthochromatic film is blind to red light it can handled from start to finish under red safelight. Panchromatic film could be made this way, too, but because the sensitizing step adds red light sensitivity, every step would have to take place in complete darkness. Ugh! Sensitizing orthochromatic film that has already been cut to size means that only the very last steps — the dye bath and film loading — have to take place in the dark.

The sheet of pan film in the bi-pack above really took a beating by the time I scanned it in registration with the ortho negative. I had used up all my loose ortho sheets for making panchromatic sheets, so I had to pull a few orthos out of loaded holders. When you load film, it's all but impossible to avoid tiny scratches in the back side subbing layer. This doesn't make any difference when the film is normally exposed and processed. But, when I put the film in the sensitizing bath, the scratches really showed up. So, tip #1: handle film that's going to go into a sensitizing bath as little and as gently as possible.

Tip #2: I have been working on my sensitizing technique to make it as easy as possible. I also seem to be getting more even and consistent results. My original technique had me put the tray of water with pinacyanol chloride in another tray with a layer frozen water. The sensitizing tray stayed cold throughout the time it took to sensitize many sheets of film, one at a time. The whole process could take over an hour. Also, some of the sheets had swirly marks from what I am assuming was uneven distribution of dye in the water. The dye is amazingly potent. One drop of 1% solution turns 100 ml of water deep violet. With my latest technique I mix one drop for every 200 ml of cold (refrigerator temp) distilled water. I pour the water into a clean 2 liter soda bottle and add the dye, cap the bottle, and shake very vigorously. Then, I distribute the dyed cold water between as many individual small trays of water as there are sheets of film I want to sensitize. The "trays" are actually Glad brand food storage containers with tight, snap-on lids.

All the prep work can be done under normal red safelight. When I'm ready to sensitize I go dark except for my dim, one-bulb red LED headband. I soak all the sheets at the same time, each in their individual trays. As soon as I slip in all the sheets of film, I snap on the container lids and gently agitate each. I do that to all of them once every 30 seconds. Right now, I've been going with a total time of 10 minutes, but fewer minutes might work as well. I need to run a trial trying different times, but not today.

The more dilute solution, very evenly distributed, for a longer time, together with agitation seems to be the ticket. The water doesn't need to be on ice because the whole process only takes a few minutes. Before I attach the film clips and hang the pieces of film to dry, I give each sheet a quick rinse in a tray of clean, cold distilled water (one tray for all of them). The only downside to this approach is that it uses more dye. But, not much more and since there are about 2000 drops of dye solution in a 100 ml bottle, I figure the distilled water is a larger expense than the dye. I bought new plastic containers for sensitizing and won't use them for anything else. They are not expensive.

Next time I sensitize, I'll try to remember to take a few illustration pics and add them here.



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