Platinum Palladium Printing — Hand-Crafted Museum-Quality Photographic Prints

Platinum and palladium printing is the pinnacle of photographic printmaking. Prized for its extraordinary tonal range, archival permanence, and luminous matte surface, the platinum print has been the preferred medium of fine art photographers since William Willis patented the process in 1873. Unlike silver gelatin prints, which sit on the surface of paper, platinum and palladium metal is embedded within the paper fibres — producing an image that is literally part of the paper. This guide covers the chemistry, coating, exposure, development, and creative control of platinum/palladium printing for photographers who want to produce museum-quality hand-crafted prints.

Why Platinum and Palladium?

Tonal Range

A platinum print can render a tonal range of approximately 2.0 density units — wider than silver gelatin (around 1.8) and far wider than any inkjet print on matte paper. This means richer shadows, more nuanced highlight gradations, and a mid-tone luminosity that seems to glow from within the paper. Black-and-white photographs printed in platinum have a three-dimensional quality — a depth and subtlety that viewers describe as "breathing."

Archival Permanence

Platinum and palladium are noble metals — they do not oxidise, tarnish, or degrade. A platinum print, properly processed, is essentially permanent. The image is as stable as the paper it is printed on. This is why museums and collectors prize platinum prints above all other photographic media. While silver gelatin prints can fade, yellow, or silver-out over decades, platinum prints from the 1890s still look pristine today.

Surface and Texture

Because the metal image sits within the paper fibres rather than on top of them, the print takes on the texture and character of the paper itself. Rough handmade papers produce prints with a tactile, organic quality. Smooth hot-pressed papers produce refined, detailed images. The surface is always matte — never glossy — which eliminates glare and makes the print equally beautiful in any lighting. The paper becomes an active part of the image, contributing warmth, texture, and physical presence.

Chemistry Fundamentals

Sensitiser Solution

The sensitiser consists of two parts: a ferric oxalate solution (the light-sensitive iron salt) and a platinum or palladium metal salt solution. Ferric oxalate (Solution A) is mixed with potassium chloroplatinite (for platinum) or sodium chloropalladite (for palladium) at various ratios to control contrast and image tone. Pure platinum produces a cool neutral grey-black. Pure palladium produces a warmer brown-black. Most practitioners mix both metals ("Pt/Pd" printing) to achieve their preferred tone — a 50/50 mix is a popular starting point, giving a neutral-to-warm tone. Adding a few drops of a contrast agent (potassium dichromate or sodium chlorate as restrainer Solution C) controls contrast from very soft to very hard.

The Printing-Out vs Developing-Out Distinction

Platinum/palladium printing is a "developing-out" process: the exposure produces a faint latent image that is then chemically developed. This is different from the "printing-out" processes (like POP — printing-out paper) where the full image appears during exposure. The developing-out nature gives the printer enormous control over contrast and density during the development stage.

Essential Materials and Equipment

Paper

The paper is as important as the chemistry. Ideal papers are 100% cotton rag (acid-free), with enough sizing to prevent the sensitiser from sinking too deeply into the fibres (which would reduce Dmax — maximum density). Popular choices include Hahnemühle Platinum Rag, Arches Platine, Bergger COT 320, and Revere Platinum. Each paper has a different surface, absorbency, and tone response — testing several to find your preferred paper is part of the craft. Hot-pressed (smooth) papers yield sharp detail; cold-pressed (rough) papers add texture. Avoid papers with optical brighteners (OBAs) — they interact with UV exposure and can cause uneven tone.

Digital Negatives

Traditional platinum printing used large-format film negatives in direct contact with the paper. Today, most practitioners make digital negatives — printing a negative image from a digital file onto transparent inkjet film (Pictorico OHP or similar). The digital negative must be the same size as the final print (contact printing only — no enlargement). Creating a good digital negative requires linearisation: calibrating the printer, ink, and film combination so that the tonal values map accurately from the digital file through the negative to the final print. This calibration step — using step wedges and densitometer readings — is essential for predictable results.

UV Light Source

Platinum/palladium printing is a contact print process that requires ultraviolet light. Sunlight works (and is how the process was used historically), but it is inconsistent. A UV exposure unit — a bank of UV fluorescent tubes (BL or BLB type) in a light box, or a plate-burner style vacuum frame with mercury vapour or metal halide lamps — provides consistent, repeatable exposures. LED UV panels are increasingly popular: efficient, cool-running, and long-lasting. Exposure times range from 3 minutes to 20 minutes depending on the light source intensity and the sensitivity of the sensitiser.

The Printing Process Step by Step

Step 1 — Mix the Sensitiser

Under subdued tungsten light (not fluorescent — which contains UV), mix your ferric oxalate (Solution A) with the platinum and/or palladium salt solution (Solution B) and optional contrast agent (Solution C). A common starting formula for an 8x10 print: 12 drops Solution A + 12 drops Solution B (mixed Pt/Pd at desired ratio) + 0–4 drops Solution C. Mix in a small glass or plastic container. Total volume: approximately 1–1.5 ml. Prepare only enough for one print; the mixed sensitiser degrades quickly.

Step 2 — Coat the Paper

Using a high-quality brush (Japanese hake brush, Richeson 9010, or a glass coating rod), spread the sensitiser evenly across the paper in a quick, systematic pattern: horizontal strokes, then vertical, then diagonal. Work fast — once the sensitiser hits the paper, it begins absorbing. Over-brushing causes fibre damage and uneven tone. Under-brushing leaves thin spots and streaks. A glass rod coater (Puddle Pusher) provides the most even coat with minimal waste. After coating, allow the paper to dry in the dark — a warm hairdryer (cool setting, no UV) speeds drying, or hang in a dark cupboard for 30 minutes to an hour.

Step 3 — Expose

Place the digital negative (emulsion side down) in contact with the coated paper (sensitised side up) in a contact printing frame. Close the frame firmly to ensure full contact — any gap causes blur. Place under your UV light source. Exposure time depends on the light source, negative density, and sensitiser formula — test strips are essential when starting. A correctly exposed print shows the faint latent image emerging as a yellow-to-orange-brown tone. Over-exposure causes highlight blocking; under-exposure loses shadow detail.

Step 4 — Develop

Submerge the exposed print face-down in a tray of developer — potassium oxalate solution (room temperature for cooler tones, warmer for warmer tones) or ammonium citrate (produces slightly warmer results). The image appears almost immediately — within 5 to 30 seconds. Full development takes 2 to 3 minutes. The latent image converts to metallic platinum/palladium, locked permanently into the paper fibres. This moment — the image snapping into existence in the developer — is one of the most rewarding experiences in all of photography.

Step 5 — Clear and Wash

After development, the print must be cleared of residual iron salts. Three successive baths of dilute hydrochloric acid or EDTA (ethylenediaminetetraacetic acid) remove the iron — essential for archival permanence and clean white highlights. Each clearing bath takes 5 minutes with gentle agitation. EDTA is safer and increasingly preferred over hydrochloric acid. After clearing, wash the print in running water for 30 minutes (or use a Kodak Hypo Clearing Agent equivalent to shorten wash time). Dry flat or hang from clips.

Controlling Contrast and Tone

One of the great strengths of Pt/Pd printing is the extraordinary degree of control the printer has over the final image. By varying the ratio of platinum to palladium, you shift the image tone from cool (more Pt) to warm (more Pd). By adding drops of restrainer (potassium dichromate or sodium chlorate), you increase contrast from naturally soft to very high. By selecting different papers, you change the texture, base tone, and density. By adjusting developer temperature and duration, you fine-tune density and warmth. And by calibrating your digital negative accurately, you control the full tonal range from deep rich shadows to delicate highlight gradations. A skilled platinum printer can make the same negative look dramatically different through chemistry, paper, and technique choices alone.

Common Challenges and Solutions

Weak Dmax (Thin Shadows)

If maximum density is too low (shadows look grey, not rich black), check: paper sizing (too absorbent papers reduce Dmax), sensitiser concentration (try a slightly richer Solution B mix), humidity during coating (low humidity can reduce absorption), and negative density range (the negative may be too thin). Double-coating — applying a second coat after the first dries — also increases Dmax.

Yellow Staining in Highlights

Yellow or brown staining in the highlights indicates residual iron salts not fully cleared. Extend your clearing baths — use fresh clearing solution and ensure full 5-minute immersions in each bath. If using HCl, check concentration. If using EDTA, make sure it is fresh and at correct dilution (typically 5% solution).

Uneven Coating

Streaks, brush marks, or uneven density indicate coating technique issues. Practice on scrap paper with water dyed with food colouring to visualise your coating pattern. Use a glass rod coater for the most consistent results. Ensure the paper is flat and secure during coating — tape it to a board.

The Value of Handmade Prints

In the age of mass-produced inkjet prints, a platinum/palladium print is a handmade, unique art object. Each print is individually coated, exposed, and processed — no two are exactly alike. The metal image is embedded in the paper — it cannot be separated from its substrate. The matte surface, the tonal range, the physical presence of platinum on cotton rag paper — these qualities make a Pt/Pd print an experience that no screen or commercial print can replicate. For photographers committed to the highest expression of their craft, platinum/palladium printing remains the pinnacle.