Historical Context

Mordançage (from French mordancer, to etch or corrode) was developed by Jean-Pierre Sudre (1927–1997) in France. He adapted for prints an etch-bleach (gelatin relief) technique for negatives that Paul Liesegang had described in the 1890s. The process creates surreal, dreamlike images by selectively lifting and veiling the shadow areas of conventional silver gelatin prints.

The technique gained renewed interest in the 1990s and 2000s as photographers sought alternatives to digital manipulation for creating otherworldly imagery.

Chemistry

Mordançage Solution

Component	Amount
Distilled water (cool)	750 ml
Copper(II) chloride	10 g
Hydrogen peroxide (40 or 100 volume)	50–75 ml
Glacial acetic acid	50 ml
Distilled water to make	1 litre

Mix in this order, always adding acid to water. Mixing in the wrong order has produced clouds of noxious fumes. 40 volume peroxide works but more slowly.

Warning: The solution is corrosive and gives off irritating fumes. Wear gloves, eye protection and a mask, and work only with good ventilation.

Procedure

Print preparation: Start with a well-fixed, thoroughly washed, contrasty silver gelatin print. Fibre-based paper is preferred, though RC also works. The effect happens in the deepest blacks, so the print needs strong shadows.
Bleaching: Soak the print in water until saturated, then immerse it in the solution with constant agitation. The image fades and the shadow areas blister and begin to lift, usually within 1 to 15 minutes.
Control: The longer the bleach, the more dramatic the effect. Remove when desired effect is achieved. Different parts of the image can be masked or treated differently.
Water rinse: Rinse in softly running water to stop the bleaching action.
Manipulation: This is the creative heart of mordançage:
- Leave veils intact for ghostly effect
- Push veils aside with water stream or brush
- Remove lifted gelatin completely
- Refix to stabilise (optional)
- Combine with other processes
Redevelopment: Redevelop in standard print developer so the bleached image and the lifted veils darken again. The print can be re-bleached and redeveloped if the result is not right.
Fix and wash: The Alternative Photography article gives 3 minutes in fixer and 10 minutes' wash; wash longer if you want the print to last, since residual chemicals are a concern (see below).
Drying: Air dry or dry with care—lifted gelatin areas are fragile.

Creative Possibilities

Mordançage offers endless manipulation options:

Technique	Effect
Veils left intact	Ghostly, ethereal shadows
Veils pushed aside	Revealed paper texture
Veils removed	Sharp tonal breaks
Multiple bleaching	Layered effects
Selective masking	Localised treatment
Redevelopment	Recovered density in areas
Toning after	Colour variations

Troubleshooting

Problem	Likely Cause	Solution
No lifting	Bleach exhausted; print too weak in the shadows	Fresh solution; a more contrasty print with deeper blacks
Too much lifting	Over-bleaching	Reduce time; dilute bleach
Highlights affected	Bleach too strong	Dilute; shorter time
Fragile veils	Inherent to process	Handle carefully; document with photography
Inconsistent results	Variable print density	More consistent printing

Safety

Chemical	Hazards
Copper(II) chlorideDanger	Harmful in contact with skin.; Harmful if swallowed.; Causes skin irritation.; Causes serious eye damage.; Very toxic to aquatic life.; Toxic to aquatic life with long lasting effects.
Hydrogen peroxideDanger	May cause fire or explosion; strong oxidiser.; Harmful if inhaled.; Harmful if swallowed.; Causes severe skin burns and eye damage.
Acetic acidDanger	Flammable liquid and vapour.; Causes severe skin burns and eye damage.

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
Copper(II) chloride	Harmful if swallowed or in contact with skin; causes serious eye damage; very toxic to aquatic life	Gloves; eye protection; collect used solution as hazardous waste, do not pour down the drain
Hydrogen peroxide (40–100 volume)	Oxidiser; causes severe skin burns and eye damage at these strengths; harmful if swallowed or inhaled	Gloves; eye protection; keep away from combustibles. In the UK, above 12% w/w (roughly 40 volume) it is a regulated explosives precursor and the public need a licence
Glacial acetic acid	Flammable; causes severe skin burns and eye damage; irritating vapour	Gloves; eye protection; add acid to water; good ventilation
Mixed solution	Corrosive; gives off irritating fumes; noxious fumes if mixed in the wrong order	Mask and good ventilation (extraction if possible); never mix with other chemicals

This is one of the more hazardous alternative processes. Read the safety data sheet for each chemical before mixing, wear gloves, eye protection and a mask, and work only with good ventilation.

Print Archival Considerations

Mordançage prints may have compromised archival properties:

Lifted gelatin areas are physically fragile
Residual chemicals may remain in paper
Consider the prints as unique objects requiring careful storage
Document important work photographically

Sources

Mordançage, AlternativePhotography.com (Cara Lee Wade)
The Chemistry of Mordançage, a Historic Photographic Process, Analytical Chemistry (ACS), 2019
Hydrogen peroxide substance information, ECHA
Explosives precursors and poisons: list of chemicals, Home Office (GOV.UK)
The Experimental Darkroom, Routledge

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

Mordançage

At a glance

Image characteristics

Key chemicals