Historical Context

Patented in 1889 by W.W.J. Nicol, the kallitype is an iron-silver process sometimes called "the poor man's platinum" because it can produce similar tonal qualities at lower cost. When toned with platinum or palladium, the results can closely resemble true platinum prints.

Key Differences from Van Dyke

Uses ferric oxalate instead of ferric ammonium citrate
Develop-out process (requires chemical development)
Greater contrast control through developer choice
Generally superior tonal range

Chemistry

Sensitiser

Solution A — Silver Nitrate (10%)

Component	Amount
Silver nitrate	10 g
Distilled water	to 100 ml

Solution B — Ferric Oxalate (20%)

Component	Amount
Ferric oxalate	20 g
Distilled water	to 100 ml

Working Solution: Mix equal parts Solution A and Solution B immediately before coating; about 2 ml covers an 8 x 10 in print (Sandy King). King suggests making up the ferric oxalate about 24 hours before use. Some published recipes add a little oxalic acid to the ferric oxalate; see the safety table if yours does.

Shelf Life: Mix the sensitiser just before coating and do not keep the mixture.

Developers

Kallitype offers contrast control through developer choice:

Sodium Citrate Developer (20%)

Component	Amount
Sodium citrate	200 g
Water	1 litre

"Classic" Borax and Rochelle Salt Developer

Component	Amount
Borax	100 g
Sodium potassium tartrate (Rochelle salt)	75 g
Tartaric acid	3 g
Demineralised water	1 litre

Other developers, such as potassium oxalate or Rochelle salt alone, are also used. Take their strengths from a published recipe (Nelson, James) rather than from memory.

King also describes adding a small amount of potassium dichromate to the developer for contrast control. It is a Category 1B carcinogen, mutagen and reproductive toxin, so this guide gives no quantities; read King's article and the hazard data first, or choose a different negative instead.

Development time: 2 minutes. The image appears within 15-30 seconds, but the full time helps remove residual iron.

Procedure

Paper preparation: Cotton rag paper with good sizing. Paper may be pre-cleared in dilute citric acid bath and dried.
Coating: Under subdued light, mix sensitiser and apply to paper. Dry in darkness.
Exposure: Contact print under UV light (time varies with light source and negative density, so make a test strip). Image should appear as pale yellow-brown. Shadows should show slight definition but highlights remain pale.
Development: Slide print into developer face-down, then turn over. Image appears within 15-30 seconds; develop for the full 2 minutes.
Water rinse: Brief rinse after development.
Clearing: Clear in two baths of 3% citric acid (30 g per litre), about 5 minutes each, to remove residual iron (King). A print that takes much more than 10 minutes to clear is marginal.
Toning (recommended): Gold, palladium or platinum toning, done before fixing, greatly improves permanence. Selenium toning, if used, comes after fixing.
Fixing: Fix in 50 g sodium thiosulfate, 10 g sodium carbonate and 2 g sodium sulfite per litre for 4 minutes (or two baths of 2 minutes each).
Washing: Treat in 1% sodium sulfite for 2 minutes, then wash for 20-30 minutes (about an hour without the sulfite bath).

The contact printing frame for a kallitype exposure: negative emulsion side down, coated paper against it, glass towards the light.

Toning

Platinum Toner (produces platinum-like permanence)

Component	Amount
Potassium chloroplatinite (20% solution)	5 ml
Citric acid	5 g
Water	1 litre

Tone for 5-20 minutes (about 5 minutes at these dilutions) until desired colour achieved, then rinse for 60 seconds. Platinum toning produces neutral to cool grey-black tones.

Palladium Toner

Component	Amount
Sodium chloropalladite (20% solution)	5 ml
Citric acid	5 g
Water	1 litre

Produces warmer tones than platinum.

Safety

Chemical	Hazard	Precautions
Silver nitrate	Causes severe skin burns and eye damage; oxidiser; very toxic to aquatic life	Gloves and eye protection essential; keep away from combustible materials; do not pour down the drain. Black skin stains are not permanent and wear off as the skin renews
Ferric oxalate	Harmful if swallowed or in contact with skin; a reportable poison in the UK (metallic oxalates)	Gloves; avoid ingestion
Oxalic acid (only if your recipe adds it)	Harmful if swallowed or in contact with skin; a regulated poison in the UK above 10% w/w (licence needed for the public)	Gloves and eye protection
Potassium chloroplatinite	Toxic if swallowed; causes serious eye damage; may cause asthma symptoms if inhaled and skin allergy	Gloves and eye protection; avoid breathing dust
Sodium chloropalladite	Causes serious eye damage; harmful if swallowed; may cause skin allergy; very toxic to aquatic life	Gloves and eye protection
Potassium oxalate	Harmful if swallowed or in contact with skin; a reportable poison in the UK (metallic oxalates)	Gloves
Citric acid	Causes serious eye irritation	Eye protection

Sources

The Kallitype Process, Sandy King, AlternativePhotography.com
The iron-silver processes, AlternativePhotography.com (classic developer)
Potassium tetrachloroplatinate substance information, ECHA
Silver nitrate substance information, ECHA
Supplying explosives precursors and poison substances: list of chemicals, GOV.UK Home Office

This guide combines established practice with community experience. Always follow safety precautions and cross-reference with primary sources before mixing chemicals.

Kallitype

At a glance

Image characteristics

Key chemicals