Photographic Paper

Part of Photography

Photographic paper is base paper coated with a light-sensitive silver halide emulsion, used to produce positive prints from negatives — the tangible, distributable output of the photographic process.

Why This Matters

Glass plates produce excellent negatives, but they are heavy, fragile, and produce mirror-reversed images. Prints on paper are the practical output of photography — portable, distributable, durable when properly processed, and directly readable without any optical device. A map photographically reproduced on paper can be rolled up, carried across rough terrain, and distributed to a dozen people. A glass plate cannot.

Photographic paper is also the entry point to the photographic system for people who cannot yet make cameras or glass plates. The simplest printing process — cyanotype on paper — requires no silver, no glass, and no camera at all. Documents can be contact-printed directly onto sensitized paper with nothing more than sunlight, a piece of glass, and simple iron chemistry. More sophisticated silver printing papers, once you have silver nitrate and appropriate base paper, allow production of prints with rich tonal range and archival permanence.

Making your own printing paper also means complete independence from supply chains. The raw material — paper — can be made from plant fibers. The sensitizing chemicals can be synthesized from accessible sources. A complete photographic printing system can operate with only local materials.

Base Paper Selection and Preparation

The base paper determines the final print quality. Not all paper is equal.

Ideal base paper properties:

• Smooth surface: texture in the base paper becomes visible in the image
• Dense, close weave: porous paper absorbs too much emulsion, producing weak, uneven coats
• Moderate thickness: too thin tears when wet; too thick makes contact printing less sharp
• Chemically neutral: acidic paper (most modern wood-pulp paper) slowly destroys silver images. Rag paper (from cotton or linen fiber) is naturally more neutral and was the standard for 19th-century prints.

Making rag paper (brief summary): Cotton or linen textile scraps, boiled in water with wood ash (alkaline), beaten to a fine pulp, formed on a wire screen, pressed, and dried. The resulting sheet is smooth, relatively strong, and chemically neutral. See the paper-making articles for full procedure.

Sizing the paper: Raw paper is too absorbent for good emulsion coating. A sizing layer reduces absorption and provides a smooth coating surface.

1. Dissolve 5 g of animal gelatin in 500 mL warm water
2. Add a small amount of chrome alum (1 g) as hardener to prevent the size from redissolving during emulsion coating
3. Brush evenly onto paper and allow to dry
4. Alternatively, use a 2% starch solution (from arrowroot or other starch sources) as a simpler sizing that does not require gelatin

Sized paper can be coated with any silver emulsion. Unsized paper requires much heavier emulsion applications for comparable results.

Silver Chloride Printing-Out Paper

The simplest silver printing paper. The image forms directly during exposure (printing-out), without development. Very easy to make.

Preparation:

1. Dissolve 5 g sodium chloride in 100 mL water
2. Brush evenly onto sized paper; dry completely
3. In total darkness: dissolve 10 g silver nitrate in 100 mL distilled water
4. Brush over the dry salted paper; silver chloride forms in the paper fiber
5. The paper is now pale cream-yellow — light-sensitive
6. Dry in complete darkness; store in light-tight box

Use:

1. In the darkroom, place sensitized paper under a negative in a printing frame
2. Expose to sunlight through the glass and negative
3. The image prints out visibly as exposure proceeds — it appears as a reddish-brown print-out image
4. When sufficiently dark (the image will lighten during fixing), return to darkroom
5. Fix in sodium thiosulfate solution for 5-10 minutes
6. Wash for 30 minutes; dry

Toning (gold toning — for permanence):

1. After fixing, before washing, immerse in gold chloride solution (0.1 g gold in 500 mL water with 5 g sodium thiosulfate)
2. 5-10 minutes immersion converts the silver to gold-silver, changing color from orange-brown to warm purple-brown
3. Gold-toned prints are dramatically more permanent than untoned silver prints

Gelatin Silver Bromide Printing Paper (Develop-Out Paper)

More sensitive and capable of finer tonal gradation. Requires development.

Emulsion preparation: Same as the gelatin dry plate emulsion, but modified for printing paper use:

• Use the same recipe (potassium bromide + silver nitrate in gelatin)
• But use shorter digestion time (15-20 minutes instead of 45-60 minutes)
• The result is a slower, finer-grained emulsion — better for printing quality
• The developed paper gives a rich, neutral-black image with full tonal range

Coating:

1. Brush or flood onto sized paper in dim red safelight
2. Dry face-up in dust-free conditions
3. Store in light-tight box

Use:

1. Contact print under negative as usual
2. Expose to lamp or brief daylight (1-10 seconds for lamp; fractions of a second for direct sun)
3. Develop in gallic acid or pyrogallol developer for 2-5 minutes under safelight
4. Stop bath, fix, wash as usual for glass plates

The develop-out paper gives a longer tonal scale and more control over final density than printing-out paper. You can adjust contrast by adjusting development time.

Cyanotype Paper (Blueprint Process)

The simplest photographic printing process: no silver required.

Sensitizing solution:

• Ferric ammonium citrate: 20 g in 100 mL water
• Potassium ferricyanide: 8 g in 100 mL water

Mix equal volumes of these two solutions immediately before coating. The mixed solution is yellow-green.

Coating:

1. In subdued indoor light (not bright sun), brush the mixed solution onto paper
2. Dry in the dark (or in dim indoor light away from windows)
3. Store in dark box; shelf life several days

Exposure:

1. Place sensitized paper under a negative or directly under a document
2. Cover with glass and expose to bright sunlight
3. The paper changes from yellow to dark blue-gray during exposure
4. Expose until the image appears fully formed (typically 5-20 minutes in direct sun)
5. Rinse in plain water — the image turns bright Prussian blue; unexposed areas wash out
6. No fixing required

Cyanotypes cannot reproduce fine tonal gradations as well as silver papers, but they are excellent for line drawings, documents, maps, and any image that is primarily black-and-white line work rather than continuous-tone photography.

Testing Paper Quality

Before committing a batch of paper to important work, test it:

Sensitivity test:

1. Coat a strip of paper
2. Expose it in contact with a step scale (a piece of glass with painted gradations from clear to dark)
3. Develop and fix normally
4. The resulting gradation shows you how the paper responds to different exposure levels

Maximum density test: Expose a piece of paper to very bright light for an extended period (5× longer than normal). After development and fixing, this should show the deepest black the paper can produce. Thin or low-quality emulsions produce gray rather than black at maximum density.

Fog test: Place a piece of coated paper in the darkroom under safelight for 5 minutes, then fix without exposure. Any overall grayness indicates fog — from the safelight being too bright, paper too old, or contaminated chemistry.

Print Presentation and Storage

Photographic prints are permanent records only if properly handled:

Mounting: Dry prints completely before mounting. Use an adhesive that is water-soluble (in case the print needs to be removed later): starch paste or animal gelatin glue is appropriate. Never use rubber cement — it deteriorates and stains.

Storage: Interleave prints with neutral paper. Never store prints face-to-face — emulsions can stick together. Avoid rubber bands, which emit sulfur. Store in cool, dry conditions; warmth and humidity promote fungal growth on the gelatin.

Labeling: Write identification on the back of the print in pencil (ink can transfer to the emulsion face and damage adjacent prints). Or attach a label to the back with a few drops of starch paste. Never write on the face of a photographic print.