Platinum/Palladium Printing: A Brief Outline

Step by Step

1. Coat and dry the paper.
2. Expose to UV light.
3. Develop:  2-5 minutes.
4. Clear:  3 trays, 5 minutes each.
5. Wash:  15-30 minutes in running water.
6. Dry:  face up on screens, or hang.

Negatives

Negatives for platinum/palladium (pt/pd) should have a density range of 1.2 to 1.8. If the negative prints well on grade 0 or 1 silver paper it should be suitable for pt/pd. Original large-format camera negatives are great for pt/pd, but enlarged negatives made either photographically or digitally can also work well.

For in-camera negatives, a good starting point is to increase your standard development time by 40-50 percent. For example, if your normal development time for TMY (400) in D-76 1:1 at 75°F is 6 minutes for a negative to be printed on grade 2 silver paper, increasing the time to 9 minutes should yield a negative suitable for pt/pd.

Some workers have found that the use of a staining Pyro developer such as PMK provides a negative suitable to both silver and Pt/Pd.

Digital Negatives

See other articles for details relevant to specific printers and methods.

Contrast Control

There are several ways that we can control and alter contrast in Platinum/Palladium Printing. The most commonly used method, which uses 2 bottles of Ferric Oxalate sensitizer, is often referred to as the A-B or traditional method. Bottle A is plain Ferric Oxalate while bottle B is modified by adding .06% potassium chlorate as a restrainer to increase print contrast. The following table illustrates the range of contrast control possible with this method. Be aware that higher contrast mixtures may produce an undesirable graininess in the image, and also require increased exposure times.

Mixture #	Negative Density Range		Coating Solution in Drops
	Pt/Pd	Pd	A	B	C/D
1	1.90	2.05	12	0	12
2	1.65	1.90	11	1	12
3	1.50	1.75	10	2	12
4	1.45	1.65	9	3	12
5	1.40	1.55	8	4	12
6	1.35	1.45	7	5	12
7	1.30	1.35	6	6	12
8	1.25	1.30	5	7	12
9	1.20	1.25	4	8	12
10	1.15	1.20	3	9	12
11	1.10	1.15	2	10	12
12	1.07	1.10	1	11	12
13	1.05	1.05	0	12	12

Coating The Paper

Brush Method: 

Hake or other natural bristle brush, or disposable foam brush. Brush should be dampened with a 2 or 3 drops of distilled water. This prevents the brush from absorbing too much solution, however, too much water will dilute the solution. Solution is poured in center of paper and then spread over desired area using light pressure on brush. To avoid raising paper nap, do not over-brush. After coating brush must be thoroughly washed. First rinse in water, then soak in clearing bath, then rinse again in water. Hang to dry.

Tube Method:

Glass or acrylic tube or rod with handle attached. Length of tube should be about 1 inch longer (wider) than area to be coated. Paper is placed on smooth, flat glass surface. Tube is placed at one edge of area to be coated and solution is poured along its length. Tube is then drawn the length of the area to be coated with light pressure. Lift the tube over the bead of liquid and set back down on paper. Make another pass back to where you began. Repeat four or five times.

As a starting point, to coat for an 8×10 inch negative to be printed on Cranes Platinotype paper using the tube method, I use 1ml ferric oxalate plus 1ml palladium (and/or platinum) plus 2 drops hydrogen peroxide. With the brush method using droppers, 24 drops oxalate plus 24 drops pt/pd plus 2 drops peroxide. This is about 50% more solution than needed with the tube method.

Dry with hair dryer. Keep moving continuously at about 10-12 inches above paper. When front appears dry, turn paper over to dry from the back. Then dry front again. This procedure should take about 5 minutes.

Exposing The Print

The pt/pd process is primarily sensitive to ultraviolet light in the range of 360-440 nanometers.

Light sources:

• Sunlight
• BL or AQA fluorescent tubes
• Mercury Vapor or Metal Halide (e.g. NuArc, Olec, Violux)

Printing times for well-made negatives should be in the range of 5 to 10 minutes. Actual times may range from 2 to 20 minutes. Use a contact printing frame, heavy glass on foam, or vacuum easel.

Materials

The Sensitizer

• Ferric Oxalate – Fe₂(C₂O₄)₃

Most commonly used method of contrast control uses a second ferric oxalate solution containing a small amount of potassium chlorate as a restrainer. The two solutions are mixed in various ratios to control contrast. More chlorate increases contrast. Unfortunately, it also increases graininess.

Ferric Oxalate A

• 15 gm  Ferric oxalate powder
• 1 gm  Oxalic acid (optional)
• 1 gm  EDTA (optional)
• 55 ml   Distilled water @ 180°F

Ferric Oxalate B

• 15 gm  Ferric oxalate powder
• 0.33 gm  Potassium chlorate
• 1 gm  Oxalic acid (optional)
• 1 gm  EDTA (optional)
• 55 ml   Distilled water @ 180°F

The Metals

• Platinum Solution (Potassium Chloroplatinite – K₂PtCl₄)
• Palladium Solution (Sodium Chloropalladite – Na₂PdCl₄)

These may be used separately or in combination. Straight platinum will yield a very neutral grey scale, though it tends to be grainy. Straight palladium is much warmer in color and also is slightly lower in contrast. They may be combined in any ratio necessary to achieve the desired effect.

The sensitizer and metal solutions are combined in equal amounts in a shot glass or similar container. The usual method of measurement is drops. I prefer to use syringes or plastic pipettes of 1 or 3 ml.

The exact amount of “emulsion” needed will depend upon the size of the area to be coated, the absorbency of the paper, and the coating method used.

For each milliliter of “emulsion”, some workers add 1 drop of hydrogen peroxide. Ferric oxalate is an unstable compound – it decays into ferrous oxalate which is useless for our purposes. Hydrogen peroxide causes any ferrous ions to become ferric. My tests show that this results in cleaner highlights even with freshly mixed ferric oxalate. Ideally you shouldn’t need it, but it doesn’t hurt.

The Developer

The most commonly used developers are Potassium Oxalate and Ammonium Citrate. I prefer the former for several reasons. It produces warmer tones, it does not become exhausted but can be replenished as needed and used indefinitely, and it can be used with the dichromate method of contrast control.

Developers may be used at room temperature or heated to as high as 140°F. Higher temperature will produce warmer image color. Develop for 2-3 minutes.

The Clearing Bath

Clear 5 minutes in each of 3 baths, with constant agitation in first bath, to remove residual salts of iron, platinum and/or palladium.

• 1 liter   Water
• 1 tbsp  EDTA
• 1 tbsp  Citric Acid
• 1 tbsp  Sodium Sulfite

After every 2-4 prints (depends on size), dump first tray, second tray becomes first, third becomes second, mix fresh bath for third tray. The first tray does the heavy lifting and will take on a yellowish tint fairly quickly. When you begin to see a bit of yellow in the second tray, it is time to dump the first, rotate the second to first position, third to second and make a fresh third. Third clearing bath should always be absolutely clear.

Some combinations do not work well. For example, EDTA alone does not completely clear prints developed in potassium oxalate. Also, some papers can be difficult to clear. A different and/or stronger solution may be necessary.

Other suggestions for clearing baths:

• Phosphoric acid  —  2% for platinum (24ml/liter); 4% for palladium (48ml/liter)
• Hydrochloric acid  —  1% for platinum (10ml/liter); 0.5% for palladium (5ml/liter)
• Oxalic acid
• Citric acid – 1 tbsp per Liter (~2%)
• Kodak Hypo Clearing Agent (main ingredients are sodium sulfite and EDTA)
• EDTA (ethylene diamine tetraacetic acid tetra-sodium salt)  —  2-3%

The Paper

Some papers that may work well for pt/pd are listed here:

• Arches Platine
• Bergger COT320
• Bienfang 360 Graphics Marker
• Cranes Cover (aka Platinotype)
• Fabriano Artistico
• Fabriano Perusia
• Gampi Torinoko
• Magnani Revere
• Masa
• Rising Drawing Bristol
• Rives BFK
• Stonehenge
• Twinrocker Watercolor
• Van Gelder Simili Japon

Unfortunately, many of the readily available watercolor and printmaking papers, such as Arches Watercolor and Rives BFK, don’t work well for pt/pd printing. The reason for this seems to be that their pH is too high, i.e. too alkaline. Some of these may work if acidified by presoaking in a 1-2% solution of Oxalic Acid.

Some papers may respond well to the use of a surfactant such as Tween 20 which is usually used as a 10% dilution. Start with 1 drop per milliliter of coating solution. The ideal amount may vary among different papers.

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Suppliers

Bostick and Sullivan
PO Box 16639
Santa Fe, NM 87506-6639
505-474-0890
http://www.bostick-sullivan.com

Photographers Formulary
PO Box 950
Condon, MT 59826
800-922-5255

Artcraft Chemicals
PO Box 583
Schenectady, NY 12301
800-682-1730

Daniel Smith
4150 First Avenue South
PO Box 84268
Seattle, WA 98124-5568
800-426-6740

New York Central Art Supply
62 Third Avenue
New York, NY 10003
800-950-6111

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Bibliography

Books:

Arentz, Dick. Platinum Palladium Printing.  Focal Press, 1999.
Crawford, William.  The Keepers of Light. Morgan & Morgan, New York, 1979.
Malde, Pradip and Ware, Mike.  A Contemporary Method for Making Photographic Prints in Platinum & Palladium. 1988.
Nadeau, Luis.  History and Practice of Platinum Printing. 3rd revised edition. Fredericton, 1994.
Pizzighelli, Captain and Hubl, Baron A.  Platinotype. Harrison & Sons, London, 1886.
Rexroth, Nancy.  The Platinotype. Violet Press, 1977.
Shillea, Thomas John.  Instruction Manual for the Platinum Printing Process. 1986.
Sullivan, Richard.  Labnotes. Bostick & Sullivan, 1982.
Sullivan, Richard and Weese, Carl.  The New Platinum Print. Working Pictures Press. 1998.

Articles:

Malde, Pradip.  New Solutions for Platinum Printers. View Camera, September/October 1994.
Rudiak, John.  The Platinotype. View Camera, January/February 1994.
Rudiak, John.  Creating a Platinotype. View Camera, July/August 1994.
Tice, George.  Processes: Palladium & Platinum. Modern Photography, March 1971
Ware, Michael J.  An Investigation of Platinum and Palladium Printing. The Journal of Photographic Science, Vol.34, 1986.

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