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There are two common processes used in making daguerreotypes. The first method is more traditional and uses mercury vapors to develop the image. The second method is called the Becquerel process after its discoverer Edmond Becquerel. This method uses the filtered light to develop the image so is less toxic than the traditional mercury version. The images using the Becquerel process tend to have less tonal range and take far longer to develop. This version is a good place to start learning is it is less complicated and less dangerous.
Main Article: Silver Polishing
The first step is to polish the daguerreotype plate. This is often considered the most difficult part of the daguerreotype process. The goal is to achieve a perfect mirror polish. This allows for even sensitization, faster exposures, and clean images with deep blacks. Various methods of polishing are used and range from historic buffing paddles to contemporary buffing wheels and random orbital sanders.
Main Article: Sensitizing
Once a daguerreotype plate has been polished, it must then be sensitized. This is accomplished by exposing the plate to the vapors of iodine and bromine. For daguerreotypes using the Becquerel process, the plate is only sensitized over iodine.
Main Article: Exposure
Daguerreotypes are not as light sensitive as other photographic processes and thus require longer exposures in the camera. Plates are also predominantly sensitive to blue and UV light which makes it more difficult to predict their exposure time.
Traditional mercury daguerreotypes that have been sensitized to iodine and bromine are generally exposed for a few seconds. Becquerel plates which have only been sensitized to iodine tend to be much slower and require exposures of several minutes.
Developing brings out the latent image that has been exposed onto the plate. This aspect crucial to the majority of photographic processes was first discovered and published by Daguerre.
Main Article: Mercury Development
This is the original method used by Daguerre and the majority of historical daguerreotypists. It consists of using a device which allows the fumes from warmed mercury to develop the image on the plate. A common design of the mercury pot is the inverted pyramid. The mercury sits on the bottom, narrow end and is heated from below using an alcohol lamp or electric heater. The plate is then placed in a holder on top of the pot for a specified time. The mercury must be kept at a constant temperature, if the mercury is too hot it will condense on the plate and ruin the image. If it is too cold the plate will not develop. Over development can also result in frosting of the plate where small mercury droplets form inthe shadow areas of the plate.
Main Article: Becquerel Development
Becquerel daguerreotypes are developed using orange or red light over a period of a few hours. Often the film or plate holder used during exposure is covered by a red or orange film such as Rubylith. This is then exposed to the sun or under an incandescent lamp for several hours. With a well prepared and exposed plate the image can start to be seen within the first 15 minutes of development.
Main Article: Fixing
Historically called clearing, fixing is required to remove the remaining light sensitive coating of the plate. Daguerre originally used a saturated solution of sodium chloride (table salt) but the discovery of the use of sodium thiosulfate by John Herschel was more effective was widely adopted. Today a number of chemicals are used including sodium thiosulfate, ammonium thiosulfate, and potassium cyanide.
Main Article: Gilding