Platinum/Palladium Print – Rare Precious Metal Classical Print, Top-Quality Long-Lasting Preservation Notes

1. Why is platinum printing known as the "supreme crown" of the photography darkroom?

Since the British chemist William Willis invented the platinum process in 1873, masters such as Alfred Stieglitz, Edward Weston, and Irving Penn have pushed it to the ultimate palace of human visual art:

1. The absolute eternity of chemical inertness (Eternal Longevity):

• Ordinary silver salt photos are composed of metallic silver. Silver easily reacts chemically with sulfur dioxide in the air and becomes sulfurized, turning black, yellowing and fading;
• Platinum (Platinum/Platinum) and Palladium (Palladium) are the most chemically stable rare precious metals on the earth. They are absolutely resistant to acid, alkali and strong oxidation (even if they are soaked in strong nitric acid, they will not be damaged at all).
• The preservation life span exceeds the paper itself: A completely washed platinum print, as long as the pure cotton paper fibers carrying it are not naturally weathered and decomposed, the image can be preserved for more than a thousand years at room temperature without fading or yellowing**!

2. Deep matte texture that penetrates deep into the marrow of cotton fiber:

• Traditional photo paper is coated with a thick layer of gelatin emulsion on top of the paper base, and the image is suspended inside the gel (it has a plastic-like sheen);
• The platinum sensitizer penetrates directly and completely into the internal plant fibers of the pure cotton watercolor paper;
• The final metallic platinum precipitation is completely integrated with the paper fiber itself. The surface presents a deep matte suede texture with absolutely zero reflection. The highlights are as warm and moist as jade, and the dark layers are delicate and extended, giving it a breathtaking feeling.

2. Core chemical reagent formula (iron oxalate + potassium chloroplatinate / sodium chloropalladate)

The platinum-palladium process usually uses a mixed formula (Platinum/Palladium Mix). Palladium provides a warm and mellow dark brown tone, and platinum provides a strong and cold deep black and high contrast:

1. Liquid No. 1 (high-gloss contrast iron salt):

• 20% Ferric Oxalate solution + 0.12% potassium chlorate (used to forcefully increase contrast).

2. No. 2 solution (standard contrast iron salt):

• 20% pure iron oxalate in water (for smooth mid-tone transitions).

3. No. 3 solution (platinum salt mother liquor):

• Weigh 2.0 grams of pure Potassium Tetrachloroplatinite ($K_2PtCl_4$) and dissolve it in 10ml of distilled water (it is as expensive as gold, use a micropipette to calculate it drop by drop).

4. No. 4 solution (palladium salt mother liquor):

• Weigh 1.8 grams of Sodium Tetrachloropalladite ($Na_2PdCl_4$) and dissolve it in 10ml of pure water.

3. Paper requirements, microdropper preparation and light-proof drying

1. Paper acid resistance and substrate purity:

• Special classical photo printing paper (such as Italian Fabriano Artistico, Arches Platine) that is absolutely 100% pure cotton velvet and has zero calcium carbonate buffer must be used;
• If the paper absorbs too much water, it needs to be soaked in 2% pure edible gelatin warm water solution or rice starch paste for "pre-sizing".

2. Microdropper mixing according to the proportion (taking a single 8x10 inch frame as an example):

• In a small glass measuring cup, use a plastic precision dropper to add:
• Liquid No. 1: 3 drops (finely adjust the contrast);
• Liquid No. 2: 9 drops (iron salt main body);
• Platinum Liquid No. 3: 6 drops;
• No. 4 palladium liquid: 6 drops;
• Total 24 drops (approximately 1.2ml) Precious metal mixed potion.

3. Handmade glass push rod spreads evenly (Glass Coating Rod):

• Place 24 drops of liquid medicine in a straight line on the top of the pure tissue paper;
• Hold the special high-precision cylindrical heavy glass pusher (Puddle Pusher) with both hands, slide it down smoothly and evenly from top to bottom along the paper surface and push it 3 to 4 times;
• The medicinal liquid instantly forms an extremely uniform and pure yellowish film, which is completely absorbed into the fiber;
• Place in absolute darkness and allow to air dry at 50% relative humidity.

4. Ultraviolet contact exposure, strong ammonium oxalate development and iron removal cleaning

1. Contact strong UV exposure:

• The platinum paper must be exposed in contact with a large-format negative (or an ultra-high-definition digital negative with carefully calibrated contrast curves);
• Exposure in a high power 365nm UV light box for 5 to 10 minutes.

2. Thrilling "One second instant development" (Developer Clearing):

• Prepare 30% ammonium oxalate or potassium citrate warm water solution (heat to 25℃~30℃);
• Slide the seemingly imageless yellowish paper quickly and decisively into the developer tray!
• A miracle breaks out instantly: At the 0.5 second moment when the liquid medicine contacts the paper, the originally invisible latent image instantly turns into an unparalleled deep, dark, and magnificent metallic platinum image at an astonishing speed like a nuclear explosion! This kind of visual impact that bursts out in one second is a shock that cannot be matched by any darkroom craftsmanship.

3. Three times of EDTA chelation iron removal bath (absolutely don’t be lazy):

• A large amount of yellow iron oxalate remains in the developed paper; if not completely removed, the iron ions will oxidize in the next few decades, causing the paper to become permanently yellow and brittle;
• Continuously immerse in three separate 2% EDTA Disodium + 1% sodium sulfite cleaning trays, rinse for 5 minutes each;
• EDTA's powerful chelating agent completely captures and dissolves even the last iron atom hidden in the paper fiber, until the water flowing out of the cleaning solution appears absolutely colorless and pure white.

4. Ultimate Drying:

• Clamp on wooden clamps and dry naturally in the shade. When an original platinum painting exuding the eternal luster of precious metals is completely flattened on a dry table, its calm aura and century-old immortal vitality will make the viewer completely lose their breath the moment their eyes touch it.

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