The Darkroom

Usually when you are traveling, you can't take your entire darkroom with you. However, you still might want to make a few, quick, color prints while you're away from home. All you need to make great color prints from color negatives is a simple black and white enlarger, some filters, three trays, and some of the special color chemicals known as "ambient temperature" RA-4 chemicals. There's no tight temperature control required. There's no critical timing required. You can use anybody's RA-4 color printing paper. And, the chemicals will keep for months--even after it has been mixed and partly used.

I hope that once you see how easy it is, and what great results you can get, that you'll want to do more advanced color printing. Printing color negatives with a black and white enlarger is referred to as tricolor printing.

Think of tricolor printing as sort of riding a bicycle. Someday you'll want to advance and get your first automobile, a late model used car, maybe. Then later you might want to advance some more and get a brand new sports car with all the accessories.

Equipment Needed. You'll need a basic, black and white condenser enlarger. Most cool-light enlargers do not have enough warm-colored light waves in their output for color work. Your enlarger doesn't have to have a filter drawer, since the filtration is done with the tricolor filters which are usually handheld under the lens.

You'll need some method of timing the exposures on your enlarger. An enlarging electronic digital timer is best. I recommend the Beseler Audible/ Repeating Enlarging Timer, Cat. No. 8177. But, in a pinch, even a wrist watch can be used.

Color printing paper is very sensitive to all colors of light, and should be handled in total darkness. The red-colored safelight that you might have used when printing on black and white papers will fog color paper and must not be used.

You'll need a set of three shallow processing trays--just like what you might be using for black and white processing. They can be made of glass, plastic, or stainless steel.

You'll need some way of timing--in total darkness--the developing process. This is a short process, 40 sec to 2 minutes, depending on the ambient room temperature. Obviously, a "real" photographic processing timer is best, but in a pinch, you can always use the old counting method. It takes about one sec to say the words, "One thousand one." By counting, "One thousand one, one thousand two, one thousand three" you will have "timed" three seconds. Get the idea?

If you want to buy a nice, inexpensive process timer, I recommend the Beseler Digital Quartz Timer, Cat. No. 8520. You might be able to find a kitchen egg timer that would work.

You'll need a thermometer to measure and monitor the solution temperature.

Finally, you'll need a tray of water in which to wash your finished prints. Color prints are washed just like black and white prints. Since all color printing paper is Resin Coated (RC), it only requires 2-3 minutes of washing.

Since all color printing paper is RC, your prints will dry very nicely, and remain perfectly flat if you simply squeegee off the excess water and lay them out on a cloth towel on a table. If you're in a hurry, you can use a household hair dryer on them.

Supplies Needed. You'll need some of the special ambient temperature RA-4 color chemicals. Both Jobo and Beseler sell this type of chemicals. Do not try to use the "regular" RA-4 chemicals. It will not work correctly at room temperatures.

The special ambient temperature RA-4 chemicals can be used in open trays and at a wide range of room temperatures. The exact recommended processing time in the developer (based on the room temperature) can be exceeded by up to 50 percent. This means that while accurate timing of the process is recommended for good repeatability, it is not absolutely necessary to get reasonable results.

You'll need some "acid stop" bath to use with the ambient temperature RA-4 chemicals. It isn't critical, but the stop bath should be mixed a little more diluted than it would be if used for black and white processing, in order to protect the color bleach/fix from excessive carry-over contamination. I mix it 10ml of the orange-colored concentrate (Kodak Indicator Stop Bath) to a liter of tap water. A tray of plain water can be used as a "stop bath" in a pinch, or you can add a little household vinegar to the plain water if you have any. Vinegar contains about 5 percent acidic acid.

You'll need some RA-4 color negative printing paper. Kodak, Fuji, Agfa, Konica, and Mitsubishi all make RA-4 paper. They will all "work" with the special ambient temperature RA-4 chemicals.

About The Tricolor Filters. Special, tricolor printing filters are available to allow you to print color negatives with a basic black and white condenser enlarger.

These filters are manufactured to allow only certain, specific wavelengths of color to pass through them. The special wavelengths of red, green, and blue are carefully matched to the sensitivity of color printing paper.

The tricolor filters are held under the enlarger lens during the exposure. Three separate exposures--one red, one green, and one blue--are made for each color picture. The order in which the three color exposures are made does not matter.

When professionals make color pictures, they do not put filters in the "image beam" because a slight amount of diffusion will occur. In reality, the amount of diffusion is very slight--as long as the filters are reasonably clean and scratch-free. Your tricolor filters will last a long, long time if you take reasonably good care of them.

Protect the filters from dust and other dirt. Avoid touching them with anything, especially greasy fingers. If dust gets on the filters, blow it off using Beseler Dust Gun 22, or brush the filters lightly with a lens cleaning brush. Avoid "rubbing" the filters with anything since almost any rubbing action will tend to produce very tiny scratches that will, in turn, tend to create very subtle diffusion in the image beam.

Tricolor Printing Procedure. Three separate exposures are made onto the color printing paper, one exposure through each of the tricolor filters. Each of the three different exposures requires a slightly different time in seconds. Accurate timing is very important since the exact duration of each of the three exposures is what establishes color balance.

After the three exposures have been made, the paper is processed for the correct amount of time (see the instructions with the ambient temperature RA-4 chemicals) in the color developer, a few seconds in the stop bath, and then in the bleach/fix.

Color Balance And Density Concepts. First, establish the approximately correct density level. Then work on the color balance.
I will give you some ballpark starting-point settings to help you. But, keep in mind that there are many variables that affect the starting points.

Just as with black and white printing, you need to do a series of density and color balance testing steps to zero in on the correct density level and color balance. This is called trial and error testing.

In tricolor printing, the relationship of the time of the three color exposures establishes the color balance. However, the magnitude of the exposures also has an effect on density. Unfortunately, as you alter the magnitude of the exposures in an effort to modify the density of the print, the color balance also shifts around a little. Therefore, it is best to make the density corrections with the lens f/stop, and keep the magnitude of the exposures the same.

Let's pretend that your starting point settings were: red filter,12 sec; green filter, 14 sec; blue filter, 24 sec.
The relationship of the three exposures is "12-14-24." That relationship produces a certain total color of light from the enlarger to the printing paper.

An identical relationship, but a different magnitude, might be "6-7-12." In this case, each of the three exposures has been reduced by half. Their relationship remains the same and the color of light that they combine to produce remains the same, but their magnitude has been reduced, so the density of the image that will be created will be one f/stop lighter than the previous exposure numbers would have produced.

In color negative printing, less light from the enlarger produces a lighter print. More light from the enlarger produces a darker print.

If you change the relationship of the three exposures from (say) "6-7-12" to something like "4-15-18," you will be altering the color balance of the print.

Correcting Density. Use the recommended starting points and make a test print at f/8 on your lens. If the print is too dark, stop the lens down (make the aperture smaller). If the print is too light, open the lens up (make the aperture larger). In color negative printing, less light from the enlarger produces a lighter print. More light from the enlarger produces a darker print.

Correcting Color Balance. When red light from the enlarger strikes the paper it stimulates the formation of cyan dye. The more red light that is used, the more cyan dye that is formed. The more cyan dye that is formed in the print's emulsion, the less the color red will be noticed in the print's image. Red and cyan have a teeter-totter relationship.

Green light stimulates the production of magenta dye. The more green light that is used, the more magenta dye that is formed. Green and magenta have a teeter-totter relationship.

Blue light stimulates the production of yellow dye. The more blue light that is used, the more yellow dye that is formed. Blue and yellow have a teeter-totter relationship.

Evaluating Color Balance. The best way to evaluate the color balance of a test print is to look at something in the image that is supposed to be a light shade of gray.

To correct the color balance of your tricolor test print, first determine which of the six photographic colors is present in excess.
If the print is too red, use more time for the red filter.
If the print is too cyan, use less time for the red filter.
If the print is too green, use more time for the green filter.
If the print is too magenta, use less time for the green filter.
If the print is too blue, use more time for the blue filter.
If the print is too yellow, use less time for the blue filter.
Changing the time by 2-4 sec will make a minor color change.
Changing the time by 5-8 sec will make a moderate color change.
Changing the time by 9-15 sec will make a major color change.

Reducing all three exposure times by 1/4 (25 percent) will increase the density of the print by 1/2 f/stop. It may also cause a slight color shift that will need to be corrected.

Reducing all three exposure times by 1/2 (50 percent) will increase the density of the print by one f/stop. It may also cause a slight color shift that will need to be corrected.

Increasing all three exposure times by 1/4 (125 percent) will decrease the density of the print by 1/2 f/stop. It may also cause a slight color shift that will need to be corrected.

Increasing all three exposure times by 1/2 (150 percent) will decrease the density of the print by one f/stop. It may also cause a slight color shift that will need to be corrected.

About Color Developer. Once the developer has been mixed, a full bottle of fresh solution should "keep" for about four months. If the solution has been partly used, a full bottle should "keep" for about three months.

About Acid Stop Bath. All acid stop bath is nothing more than mild solutions of acidic acid, which is exactly what common household vinegar is. I usually use the same acid stop bath solution that I use for black and white processing--just mixed a little more diluted. If you mix it too strong, it will tend to contaminate the bleach/fix when it is carried over into it on the wet print.

The exact concentration isn't critical. I typically mix 10ml of the orange-colored concentrate (Kodak Indicator Stop Bath) to a liter of tap water.
About Bleach/Fix. Bleach/fix used for RA-4 color processing is a fairly hardy compound that will "keep" for many months once it has been mixed.

Sources For Tricolor Printing Filters.
1) Eastman Kodak. Ask your friendly, local Kodak dealer to order for you the following Kodak Wratten Filters: Wratten No. 25 (red), No. 149-5605; Wratten No. 99 (green), No. 149-6306; Wratten No. 98 (blue), No. 149-6298.

These filters are available in different sizes. The smallest size, 75mm (3") square, is adequate for holding under the lens. Kodak also makes a metal filter holder in same size which is very nice to mount the filters in.

2) Rosco stage lighting filters. They are available from a variety of distributors such as Calumet or BML Stage Lighting Co., Inc. If you use Rosco filters, you'll have to combine a couple of different ones to produce the correct filtration. It works like this: Roscolene No. 818 plus No. 819 for red; Roscolene No. 809 plus No. 871 for green; Roscolux No. 59 for blue.

If you get the Rosco filters, you can still use the Kodak metal filter holders or you can hand make some little cardboard holders. But, you really should devise some sort of holder-- for convenience sake.

While the Kodak filters cost more, they are nice and clean with no scratches. The Rosco filters will have a few scratches, but the amount of diffusion that the scratches will produce is probably negligible in the real world. If you use filters in the filter drawer of the enlarger, then the scratches don't matter at all since they will be above the negative, and not in the image beam. But, remember that using the filters in the filter drawer might cause the enlarger to jiggle a little between the three different exposures, and cause an out-of-registration color image. I don't recommend it.

Manufacturers/Distributors
BML Stage Lighting Co., Inc.
10 Johnson Dr.
Raritan, NJ 08869
(908) 253-0888
fax: (908) 253-9530

Calumet Photographic Products
890 Supreme Dr.
Bensenville, IL 60106
(888) 888-9083
(888) 367-2781
(800) 225-8638
(630) 860-7447
fax: (800) 577-3686
www.calumetphoto.com

Charles Beseler Co.
1600 Lower Rd.
Linden, NJ 07036
(800) 237-3537
(908) 862-7999
fax: (908) 862-2464
www.beseler-photo.com

Eastman Kodak
343 State St.
Rochester, NY 14650
(800) 242-2424
(716) 724-5629
www.kodak.com

Jobo Fototechnic, Inc.
PO Box 3721
4401 Varsity Dr., Ste. D
Ann Arbor, MI 48106
(734) 677-6989
fax: (734) 677-6963
e-mail: sales@jobo-usa.com
www.jobo-usa.com