Historical Context

Announced in 1839 by Louis Daguerre, the daguerreotype was the first commercially successful photographic process. It produces a unique image on a silver-plated copper plate with extraordinary detail and a distinctive mirror-like surface.

Traditional Process Overview

The daguerreotype process involves:

Plate preparation: Silver-plated copper polished to a mirror finish using progressively finer abrasives and buffs.
Sensitisation: Plate exposed to iodine vapour, forming silver iodide on the surface. The plate cycles through colour changes (yellow → rose → violet → blue) indicating thickness of silver iodide layer.
Exposure: Plate exposed in camera. Early daguerreotypes required exposures of many minutes; later improvements reduced this to seconds.
Development: Plate developed over heated mercury (60°C). Mercury vapour amalgamates with exposed silver, forming the image.
Fixing: Unfixed silver iodide removed with sodium thiosulfate (originally sodium chloride was used).
Gilding (optional): Gold chloride solution heated over flame, poured over plate to tone and strengthen image.

Becquerel Daguerreotype

Developed by Edmond Becquerel in 1840, this variant uses only iodine sensitisation and red/yellow light development, eliminating mercury entirely.

Process

Instead of mercury development, the exposed plate is simply re-exposed to red or yellow light (filtered through coloured glass or LED). The unexposed silver iodide converts to silver under this secondary exposure, creating the image.

Advantages

No mercury required
Significantly safer
Can be done with simpler equipment
Produces subtly different tonal qualities (some practitioners prefer Becquerel tones)

Disadvantages

Longer secondary exposure required
Some report lower contrast or different tonal rendering
Less historically "authentic" (if that matters)

The Becquerel process is the recommended approach for contemporary daguerreotypists who wish to avoid mercury exposure.

Image Characteristics

Mirror-like silver surface
Extraordinary detail
Unique (non-reproducible) image
Visible only at certain angles against dark background
Extremely delicate—must be housed under glass

Handling and Care

Daguerreotypes are extremely fragile:

Never touch the image surface
Store in sealed cases to prevent tarnishing
Handle by edges only
The image can be destroyed by wiping or cleaning

Historical daguerreotypes are often found in protective cases with brass mats and cover glass.

Safety

Chemical	Hazard	Precautions
Mercury	EXTREMELY TOXIC — cumulative neurotoxin	Laboratory fume hood REQUIRED; respirator for spills; proper disposal
Iodine	Corrosive; toxic vapour	Fume hood; respiratory protection
Bromine	Extremely corrosive; toxic	Fume hood; extreme caution
Gold chloride	Toxic	Gloves

Mercury Toxicity Warning

Mercury vapour exposure causes irreversible neurological damage. Symptoms may not appear until damage is severe. Historical daguerreotypists suffered significant mercury poisoning; many experienced tremors, psychological disturbance, and premature death.

Modern practitioners MUST use:

Laboratory-grade fume hood with vaneometer-verified airflow (100+ fpm)
Mercury vapour monitoring
Proper spill containment and cleanup procedures
Mercury-rated waste disposal
Regular health monitoring

Do not attempt traditional daguerreotype without professional laboratory facilities.

Recommendation

For those interested in daguerreotype, the Becquerel variant is strongly recommended. It produces authentic daguerreotype images without the extreme hazards of mercury development. Many contemporary daguerreotypists use exclusively Becquerel development and achieve excellent results.

If you are determined to work with mercury, seek hands-on training from an experienced practitioner and ensure you have appropriate laboratory facilities before attempting the process.

Daguerreotype

Image characteristics

Key chemicals