The daguerreotype process
The daguerreotype process produces perhaps the most beautiful images of any photographic process and it is easy to be captivated by the beauty of the resulting images. However, for anyone wishing to learn the process, please take into account the following.
Firstly, the chemicals involved are extremely toxic and can cause serious harm to yourself and to the environment. The process involves iodine, bromine and mercury fumes all of which require specialist equipment, careful handling, and personal protective equipment.
Secondly, the process is long and complex. There are many variables at each stage and it can be extremely difficult to troubleshoot a failed plate. Although relatively expensive, you will save yourself time, money, and frustration by attending a daguerreotype workshop.
Finally, you might consider the Becquerel daguerreotype process which is slightly less complicated and does not involve bromine or mercury.
Having said all that, there is nothing that quite compares to a mercury daguerreotype, and this is an updated version of the process originally published by Louis Daguerre in 1839.
Polishing
Traditionally, daguerreotypes are made on copper plates coated with a thin layer of silver, either by cold-rolling or by electroplating. However, the daguerreotypes in these pages are made on pure solid silver plates to highlight the beauty of the subject being photographed, while also emphasising the value of the resulting image as a unique object.
The silver plates arrive cut to size but with sharp edges and surface imperfections. After rounding the corners and edges, the surface is polished with progressively finer jewellers' polishing compounds - yellow, white and red Dialux. It can often take several hours to prepare a plate for use and, because fine silver is extremely soft, all polishing must be carried out by hand.
Hallmarking
The plates are then sent to the London assay office where they are hallmarked with the artist's maker's mark, the fineness of the silver, the London mark and a letter signifying the year. Please see the separate hallmarking page for more details.
On their return, the plates are re-polished with red Dialux and then given a final finish using Nuvite aviation polish. The plates now look similar to the first photograph.
Finally, after ensuring the plate is completely free of any blemishes, polishing compound, or dust, the plate is hand-buffed to a mirror finish with velvet and carbon black.
Sensitising
The plate is then transferred to a fuming box where it is exposed to iodine fumes which react with the silver to produce a light-sensitive surface (photograph #2). This usually takes 10-15 seconds but achieving the correct coating can only be judged by the colour of the plate and the plate may need to be returned to the fuming box several times until it takes on the required orange-yellow hue.
After this, the plate is transferred to a separate fuming box containing bromine where the process is repeated and the yellow becomes tinged with magenta as the surface of the plate becomes coated with complex light-sensitive silver halides. Again, this can be judged by eye under subdued lighting.
The final stage is carried out under darkroom conditions using a red safe light. The plate is returned to the iodine fuming box for ten seconds, where it takes on a deep magenta colour, and is then transferred to a camera plate holder ready for exposure.
Exposing the plate
Daguerreotypes require both good lighting and relatively long exposure times. This is especially true when depth of field is required and even more so when photographing close-up.
Although there are exposure charts, and experience helps, it is not unusual to have to take several test plates before deciding on the exact exposure time necessary to produce the desired result.
Exposure times of twenty or thirty minutes are quite normal.
Developing
After removing the plate from the camera, it is transferred to the mercury box where the latent image is developed by exposure to mercury vapour at 135°F (photograph #4).
This usually takes 2-3 minutes but, again, image quality relies on precise timing. Too long and unwanted speckles start appearing, but not long enough and the resulting image is dull and lifeless.
Fixing
The plate is then submerged in a developing tray of sodium thiosulphate to fix the image and wash away any remaining photosensitive silver salts.
After this, the plate is rinsed thoroughly under running water.
Gilding
The final stage is to gild the daguerreotype using a gold chloride solution (final photograph). Not only does this improve the contrast and give the image a warmer tone but it also helps strengthen the bonds between the image and the plate, and makes the daguerreotype less susceptible to accidental damage.
All the same, the image is still quite delicate and it is important to seal the plate behind glass as soon as possible for protection.