Historical Context
Platinum printing was invented by William Willis, who patented it in 1873, and became the preferred medium for fine art photographers in the late 19th and early 20th centuries. The process fell out of favour as platinum became prohibitively expensive during World War I. The Malde-Ware method, developed by Mike Ware and Pradip Malde from the mid-1980s, modernises the 1887 printing-out process of Giuseppe Pizzighelli.
Why Platinum?
Platinum prints are among the most permanent photographs possible. The metal does not oxidise or tarnish, and the image lies within the paper fibres rather than on the surface, making it extremely resistant to physical damage.
Chemistry (Traditional Developing-Out Method)
The traditional ferric oxalate method uses three stock solutions, combined drop by drop. (The Malde-Ware printing-out method, which uses different chemistry and no potassium chlorate, is described below.)
Solution A — Ferric Oxalate (27%)
| Component | Amount |
|---|---|
| Ferric oxalate | 27 g |
| Distilled water | to 100 ml |
Solution B — Ferric Oxalate + Potassium Chlorate (contrast agent)
The same 27% ferric oxalate solution with a small amount of potassium chlorate added. Palladium needs about twice as much chlorate as platinum for the same contrast increase.
Solution C — Metal Salts
- Platinum: potassium chloroplatinite solution
- Palladium: sodium chloropalladite solution (Bostick & Sullivan supply it at 15%)
- Or a mixture of the two, to taste
Mixing Ratios for 8×10" Print
Count the iron solutions and the metal solution so that the total drops of ferric oxalate (A + B) roughly equal the drops of metal solution. Bostick & Sullivan's starting point for an 8×10" print with their platinum kit is:
- Starting point: 18 drops A + 2 drops B + 20 drops platinum solution
- Lower contrast: use less B and more A, keeping the iron total the same
- Higher contrast: use more B and less A
The Malde-Ware Printing-Out Method
Mike Ware and Pradip Malde's method replaces the traditional salts with ammonium salts and controls contrast without oxidising agents. Ware's stock solutions are ammonium ferric oxalate 60% w/v (30 g in 33 ml water, warmed to about 50 °C, making 50 ml), ammonium tetrachloroplatinate 25% w/v (5 g in 18 ml water, making 20 ml; leave it at least 24 hours before first use) and a 20% w/v palladium solution (3 g palladium chloride with 1.8 g ammonium chloride, made up to 25 ml). The iron volume equals the total metal volume: equal volumes of iron and platinum (left to stand for an hour in the dark before coating), or iron and palladium (coat immediately). About 1.2-1.6 ml covers a 10 x 8 in print. Contrast and colour are set by the platinum:palladium ratio and by humidifying the coated paper before exposure (at least 30 minutes over saturated ammonium chloride, about 80% relative humidity at 20 °C); Ware does not recommend adding potassium chlorate, dichromate or hydrogen peroxide. The image prints out during exposure, so there is no developer. Processing is: 5% disodium EDTA for 10 minutes; rinse; working-strength hypo clearing agent (or sodium sulphite) for 10 minutes; rinse; 5% tetrasodium EDTA for 10 minutes; then wash for at least 30 minutes.
Procedure
-
Paper selection: Use appropriate paper without alkaline buffers. Arches Platine is the industry standard.
-
Mixing sensitiser: Under subdued tungsten light, count required drops of each solution into a small container. Mix thoroughly.
-
Coating: Apply sensitiser to paper using glass rod or brush. Work quickly—the sensitiser absorbs fast.
-
Drying: Let the solution soak in for about 10 minutes, then dry thoroughly in darkness (a hair dryer is fine; wear a dust mask). Paper should not feel cool (indicating moisture); damp spots print blotchy.
-
Exposure: Place negative in contact frame, emulsion to emulsion with sensitised paper. Expose to UV light.
- Bostick & Sullivan: about 3–8 minutes for a 4×5 negative under a sun lamp, 3 to 4 inches from the paper; dense negatives can need half an hour or longer
- Only a faint image is visible; the full image appears in the developer
-
Development: Develop immediately in potassium oxalate developer (not in a metal tray), pouring it quickly over the print. Development is complete within seconds; most printers leave the print in for 1–2 minutes. The developer can be kept and reused.
-
Clearing: Clear in one or two baths of EDTA clearing agent with sodium bisulfite (Bostick & Sullivan: 2 tablespoons of each to 1 quart of water), 5 minutes each, until no yellow remains in the highlights.
-
Final wash: Wash for about 30 minutes in gently running water.
-
Drying: Air dry or blot and dry flat.
Paper Considerations
Requirements
- Pure cotton or linen fibre
- No alkaline buffers (these inhibit printing)
- Appropriate sizing (internal or surface)
- Smooth surface for detail; textured for softer results
Known Compatible Papers
- Arches Platine — Industry standard
- Hahnemühle Platinum Rag
- Buxton Rag
- Bergger COT320
- Legion Revere Platinum
Papers to Avoid
- Papers with alkaline buffers (most "archival" papers)
- Papers with optical brighteners
- Wood pulp papers
Negative Requirements
Platinum and palladium need negatives with a longer density range than silver printing:
- Bostick & Sullivan suggest a density range of about 1.35–1.50 for their traditional kit; contrast can then be fine-tuned with the chlorate solution
- Pure platinum without contrast agents, and the Malde-Ware method, can print longer negatives
- Digital negatives are widely used
Platinum vs Palladium
| Aspect | Platinum | Palladium |
|---|---|---|
| Colour | Neutral grey | Slightly warmer |
| Cost | Very expensive | Very expensive; at times dearer than platinum |
| Sensitisation risk | Higher | Lower |
| Permanence | Extreme | Extreme |
Many practitioners use a mix of platinum and palladium to balance cost, colour, and safety considerations.
Safety
| Chemical | Hazards |
|---|---|
| Ferric oxalateWarning | Harmful in contact with skin.; Harmful if swallowed. |
| Potassium chloroplatiniteDanger | Toxic if swallowed.; Causes skin irritation.; Causes serious eye damage.; May cause allergy or asthma symptoms or breathing difficulties if inhaled.; May cause an allergic skin reaction. |
| Sodium chloropalladiteDanger | May be corrosive to metals.; Harmful if swallowed.; Causes serious eye damage.; May cause an allergic skin reaction.; Very toxic to aquatic life with long lasting effects. |
| Potassium chlorateDanger | May cause fire or explosion; strong oxidiser.; Toxic if swallowed. |
Classifications from the European Chemicals Agency (official EU classification where one exists, otherwise the one agreed by REACH registrants or most often notified). Read the safety data sheet that comes with your chemicals, and dispose of them in line with local regulations.
| Chemical | Hazard | Precautions |
|---|---|---|
| Ferric oxalate / ammonium ferric oxalate | Harmful if swallowed or in contact with skin (H302, H312). Ferric oxalate is a reportable poison in the UK (metallic oxalates) | Gloves; avoid ingestion |
| Potassium chlorate | Strong oxidiser: may cause fire or explosion with organic materials; harmful if swallowed or inhaled. Regulated explosives precursor in the UK above 40% w/w (members of the public need an EPP licence for the pure solid) | Store away from organic materials, acids and fuels; gloves |
| Platinum salts (potassium chloroplatinite) | Danger: toxic if swallowed (H301); serious eye damage (H318); respiratory and skin sensitiser (H334, H317) | Gloves and eye protection essential; avoid dust and skin contact |
| Palladium salts (sodium chloropalladite) | Harmful if swallowed; serious eye damage; skin sensitiser (H302, H318, H317) | Gloves and eye protection |
| Potassium oxalate (developer) | Harmful if swallowed or in contact with skin (H302, H312); reportable poison in the UK (metallic oxalates) | Gloves; never use kitchen utensils |
| EDTA salts and sodium bisulfite (clearing) | Disodium EDTA: harmful if inhaled (H332); sodium bisulfite: harmful if swallowed and releases sulphur dioxide with acids | Avoid dust; mix in a ventilated space |
Platinum Sensitisation Warning
Repeated exposure to platinum salts can cause a severe allergic condition characterised by asthma, urticaria (skin rash), and contact dermatitis. It was first observed in 1911 in photographic workers handling platinotype paper. Once sensitised, the allergy is typically permanent.
Always use gloves and avoid skin contact. If you develop symptoms, discontinue platinum printing and consult a physician.
Palladium salts are not classed as respiratory sensitisers, unlike platinum salts, so they are a lower-risk choice with similar (though slightly warmer) tonal results. They can still cause skin allergy, so wear gloves with them too.
Further Reading
Pradip Malde & Mike Ware, Platinotype: Making Photographs in Platinum and Palladium with the Contemporary Printing-out Process (Routledge, 2020) 418 pages covering the Malde-Ware printing-out method. Features over 40 artists. The definitive reference for the contemporary printing-out process, the result of nearly 40 years of collaborative research.
Dick Arentz, Platinum & Palladium Printing, 2nd Edition (Focal Press, 2004) The definitive practical resource, based on over 3,000 prints. Includes contributions by Bob Herbst, Mark Nelson, Sandy King, and Stan Klimek. PDF edition includes 2018 Addendum on digital negatives.
Constance McCabe (ed.), Platinum and Palladium Photographs: Technical History, Connoisseurship, and Preservation (AIC Photographic Materials Group, 2017) 504 pages from 47 contributors. A National Gallery of Art research initiative funded by the Irving Penn Foundation. Essential for understanding the technical history and conservation of the medium.
Christopher James, The Book of Alternative Photographic Processes, 3rd Edition (Cengage Learning, 2015) Comprehensive coverage of platinum/palladium printing with practical guidance.
Mike Ware's website (mikeware.co.uk) Primary source for the Malde-Ware method, with free practical instructions and technical papers.
Sources
- The Platino-Palladiotype Process, Mike Ware
- Platinum and Palladium Printing Instructions, Bostick & Sullivan
- Palladium Solution #3 (sodium chloropalladite 15%), Bostick & Sullivan
- Potassium tetrachloroplatinate substance information, ECHA
- Supplying explosives precursors and poison substances: list of chemicals, Home Office (GOV.UK)