A Brief Guide to Becquerel Daguerreotype

A description of the daguerreotype process by Jason Greenberg Motamedi.

Always be careful when handling chemicals. Read the health and safety instructions.

Daguerreotypy is back in fashion. Contemporary daguerreotypes are featured in high circulation magazines, major museums, and galleries. Perhaps we can understand this odd resurgence as reaction to the digitalization and apparent sterilization of photography or perhaps some other early twenty-first century ailment. Yet, despite the sudden growth in interest, there are very few practicing Daguerreotypists in the world. There is a reason for these scant numbers; our Daguerre is a generous but fickle muse.

Despite their ineffable and elusory beauty, Daguerreotypy is a very difficult and expensive endeavor, yet the rewards are spectacular.

For me the most gratifying aspect of the Daguerreotype is its presence or–to make up a word–its thingness. This seems particularly important in this age of digital reproduction. A Daguerreotype, unlike a screen image and even the most perfect silver, platinum, or albumen print, is foremost a three dimensional object. Made of copper, silver, and glass they are surprisingly heavy, yet seem to fit perfectly in the palm of a hand. Finally, Daguerreotypes are all flawed. Producing a perfect blemish-free image is near impossible. I find something comforting in being forced to leave so much to chance.

A STERN WARNING: Daguerreotypy employs toxic chemicals that improperly handled can do irreparable damage to your lungs, nervous system, environment, family, pets, and neighbors. The author or website AlternativePhotography.com owners assume no liability for the risk to, or because of, persons handling any materials or chemicals mentioned below. You alone are responsible to insure that chemicals are handled, stored, and disposed of in a safe and ecologically appropriately manner according to local regulations.

A SECOND ADMONITION: Before attempting Daguerreotypy on your own, please consider attending a workshop with a practicing Daguerreotypist. Although the cost of these workshops may seem high, I believe that they will actually save you both time and money by reducing the learning curve and preventing costly mistakes. A number of workshops are taught every year. Call a craft or photography school near you and ask; if they don’t offer one suggest that they do!


Plate Making: Obtaining high quality plates is the first of many hurdles the contemporary Daguerreotypist will face. Preparing one’s own plates is not difficult, but like all things Daguerreian does take some effort. Daguerreotype plates are highly polished silver. Only pure silver will work for our purposes. Traditionally, copper plates were clad with silver and then polished. Contemporary plates are primarily electroplated copper.

Preparing Copper: Take a sheet of mirror finish engravers copper, and polish it using a slurry of extra fine grain pumice powder to a flat matt surface with no lines or marks. Taping the plate to an acrylic polishing platform will help secure it. Once polished, wrap the plates in a piece of heavy cloth or flannel and have them plated with pure silver to 1/2 mil (.0005"). Your plater may require that you drill two holes in your plate for their plating racks.

Plate Polishing: Find yourself a 6" bench grinder with at least 1/2 horse-power. Remove the grinding wheels and fit tapered spindles purchased from a jewelry supply. Next, find a solid mount, and locate the grinder somewhere that you don’t mind getting really dirty. After polishing few plates, red rouge will be everywhere. Attach the plate to a piece of 3/4" plywood slightly larger than the plate using small nails. Carefully nail the plate down, using at least six, if not eight nails.

Polishing Method: Before polishing you must first decide whether your image will be vertical portrait-orientation or horizontal landscape-orientation. We can never completely erase polishing marks; only lay down finer and finer ones. To prevent polishing from being a never-ending task it is best to situate the polishing marks in a way that they are difficult to see in ordinary light. To do so, make sure that the polishing lines always run up and down the plate, not side-to-side.

First, attach a 60-ply tight-weave fine muslin buffing wheel on one spindle and a 54-ply unstitched fine-finishing buffing wheel on the other. Using a propane torch heat up the plate until all moisture is gone, about 10 seconds. Before the plate cools down turn on the grinder, rub a bit of the rouge on the tight-weave buffing wheel, and beginning from the top rub the plate quickly back and forth horizontally on the wheel while moving the plate slowly upwards. Always begin polishing from the top of the plate; if you begin from the bottom the plate will be thrown from your hands. Once you reach the bottom, flip the plate 180 degrees. Repeat to a total of four times. Add a bit more rouge to the wheel, turn the plate 90 degrees and repeat with four passes. Once completed, move quickly to the finer wheel and repeat four passes in the same orientation as you ended.

After finishing with machine polishing carefully remove the plate from its mount, clean the edges and back of excess rouge, and place somewhere safe to cool off. At this point even the smallest amount of moisture or the lightest touch on the polished surface will send the plate back to the machines for re-polishing. Tarnish and other contaminants quickly build on the surface of the silver, contributing to fog, so sensitize your plates immediately after polishing.

Hand Polishing: While it is not necessary to hand polish, it does serve to lay down very fine polishing marks. The polishing planks are two wooden boards, for half plate or smaller use 7" x 30". Each board has two layers of very soft clean velvet stretched over several layers of heavy felt or flannel. One plank is dusted with dry powdered rouge, and the other is left without rouge. Both planks must be kept clean and dry. Move the plate up and down the buffs with a light amount of pressure. Hold the plate in the same orientation as your future image, to follow the fine polishing lines you left with the machine. Beginning with the rouged board, slide the plate up and down the board 100 or more times with light pressure. Repeat 100 or more times on the rouge-free board, starting with light pressure and slowly reducing to the weight of the plate itself. Carefully remove the plate, and sensitize immediately.

From this point on, the Becquerel process differs from the traditional Mercury process.

Sensitization: The polished plate is carefully carried into the darkroom; any marks or fingerprints will send you back to the machines. The darkroom can be safely lit by red or amber safelights, and should be very well ventilated. Standard darkroom ventilation is not sufficient. I recommend a laboratory-grade fume hood, although buying a small demonstration hood and a powerful extractor will work for small plates. If you build your own hood make sure that it extracts evenly all sides. In all cases, buy a vaneometer to test your hood, even if you purchased it new, insuring that the fume hood extracts air from ports or doors at least 100 feet per minute.

The plate is exposed to the fumes of elemental Iodine. At room temperature Iodine creates fumes that rise and react with the silver in your plate to form Silver Iodide (AgI), a light sensitive compound. The traditional Mercury developed method uses other halogens in addition to the Iodine, notably Bromine or Chlorine, to increase the spectral sensitivity and consequently the speed of the plate. Unfortunately these "quick-stuffs" do not work with Becquerel development.

Iodine fumes reacting with silver cause a beautiful color shift in the plate. Charlie Schreiner, the owner and editor of newdags.com, a wonderful reference site for all Daguerreotypists, describes these changes; "First, a pale yellow, then a darker yellow and a sequence follows that progresses through the natural color spectrum–orange, red, purple, blue, green then back to yellow" (http://www.newdags.com/becquerel.html), repeating the cycle.

The color is a good indication of how much Silver Iodide has been formed. The plates function and look best with a moderate amount of silver iodide; too little will create a faint and very contrasty image, while too much will produce a gray and flat image. Generally, I have found that the colors towards the end of the first cycle–magenta in particular–works best for me. While the second cycle colors will produce an image, I find them to be too muddy for my tastes.

Fuming Boxes: Unfortunately there are no commercially available fuming boxes. A few individuals do make them to order, but it is not difficult to make your own. I base all of my fuming boxes around glass food storage containers. These are readily available, cheap, and glass is highly resistant to the corrosive action of the halogens. A Pyrex 11 cup Food Storage Dish is perfect for full-plate. The material you choose to make your boxes must be resistant to corrosive fumes. Teflon, glass, and acrylic are excellent. Plywood is also surprising resistant. Do not make your box out of any sort of metal. If possible, do not even use nails or screws in your box. In general, I have built my fuming boxes from plywood or acrylic, holding the Iodine in a glass dish and stopping the dish with a glass or Teflon slide.

Fuming: Heat up the polished plate with a hair dryer, removing any condensation that may have formed on the plate. Slide the plate into the box, exposing it to the Iodine fumes. After about 20 seconds, pull the plate out and examine the color by looking at the reflection of a white light off a white surface. If the color is not where you would like it, slide the plate in again for another 5 to 10 seconds. Repeat if necessary. Once the plate reaches the desired color, turn the white lights off, safelight on, and slide the plate over the Iodine for eight second, just enough to erase the effects of the light. It is then removed and placed in a plate holder, making sure not to touch the place or expose it to white light.

Warning: Iodine and its fumes are very powerful oxidizers. It will not only corrode metal, but also will cauterize your lungs and burn your skin. Iodine should always be handled in a fume hood and stored in proper containers. Never touch Iodine crystals, even with a gloved hand. Finally, never heat the Iodine crystals. This is incredibly dangerous and could result in billowing clouds of corrosive and toxic Iodine gas. You should always wear safety glasses and gloves when handling Iodine or fuming.

Exposure: Daguerreotypes are considered "color blind"–sensitive only to blue and UV light–so metering in any regular manner is futile. Unfortunately for the beginner there is no easy way to determine exposure: Prior experience reigns supreme. It is very helpful to keep a detailed record of your fuming times and colors, exposures, as well as development times. Here are a few recent examples of Becquerel exposures:

  • Landscape, overcast day, 18% Gray (zone V) reading of 12ev:
    6 min @ f/5.6
  • Landscape, sunny day, 18% Gray (zone V) reading of 14ev:
    2 min @ f/5.6
  • Head and Shoulders Portrait, overcast day, skin (zone VI) reading of 12.66ev:
    1:45 min @ f/2.8.

Developing: no one has been able to explain exactly how Becquerel development works. The exposed plate is covered with an Amberlith printing screen, and is placed under bright light. The red light, to which the plate is insensitive, reacts with the Silver Iodide and enlarges Silver crystals, which make up the image. Becquerel developed plates are about 10 times (2.5 stops) slower than traditional plates, and usually have a color cast, most often blue.

After exposure, place your plate under the Amberlith printer’s screen. To make a mask, use lightly colored cardboard or matt board a few inches larger than the size of your plate. Cut a window slightly smaller than the plate and tape a piece of Amberlith over it. Then, tape strips of board on the opposite side of the mask, surrounding the plate, insuring that it can’t move during development or touch the screen. I usually tape the plate to the mask from the back. Certainly there are more elegant ways of making a mask, but none easer or more convenient.

As a light source the sun works best; on a sunny day development should take one and a half to two hours depending upon the light. Work-lights with 500-watt halogen bulbs also work well, and take about two hours. Becquerel plates are quite sensitive to heat, too much will fog them. It is best to make your mask from light colored board, although my poor example shows otherwise. Keep the mask and plate off the ground so that air can move and cool the plate. Having a powerful fan blowing on the plate is a good idea.

Fixing: Remove the developed plate from the mask in subdued light and submerge the developed plate into a fresh solution of 15g of Sodium Thiosulfate and 15g of Sodium Sulfite in 500ml distilled water. Be sure that the solution hits the plate at the same time; otherwise waves of discoloration will form on the plate. Fill an 8×10 tray with 500 ml of solution; tip the tray so all of the fluid is in one end, and place the plate on the dry end. Quickly and evenly lower the tray and rock it back and forth for twice the time it takes to completely clear the plate of Iodine. Wash the plate in slowly running tap water for five or more minutes and let sit in distilled water. The image is very delicate at this stage, and you must be very careful not to touch the image with fingers or a direct stream or spray of water.

Gilding: Gilding is the most difficult stage of Daguerreotypy. Gilded plates are more archival, much more resistant to damage, and have more apparent depth and richer tones. However, gilding is expensive and accentuates latent imperfections, apparently creating stains where there were none.

Gilding solution:

  • Part A: 1 gram of Gold Chloride dissolved in 500ml of distilled water.
  • Part B: 4 grams of Sodium Thiosulfate dissolved in 500ml of distilled water.

To make the gilding solution, add one Part A to one Part B. This means add the Gold to the Sodium Thiosulfate, the other way will precipitate the gold and ruin the solution. Allow it to sit for a full day. Keep the solution stored in a brown bottle.

How to gild: Placed the fixed and washed plate on a level laboratory stand, and quickly cover with gilding solution before it dries. Carefully pour the solution on the plate so it forms a meniscus that covers the entire surface. It is not difficult to do, but does take some practice. Make sure the plate is level or the gilding solution will run off.

Once the plate has a good meniscus, light your propane torch, and begin smoothly moving the flame over the bottom of the plate. The goal is to bring the solution just under the boiling point. It should steam and produce small bubbles, but never actually boil. Keep the torch moving so the heat is evenly disbersed.

Carefully watch the plate for the stains that will appear about halfway through the process. The whole plate will become darker, and a few stains will appear on your plate. Keep heating until the plate lightens and the stains disappear. This is a judgment that requires lots of practice and careful observation. It is far better to slightly over-gild, which creates a pleasant yellow-gold tone, than to under-gild, which leaves behind those nasty stains and a dark plate. Watching the plate in negative form, with a white wall behind or outside with the sky above, helps tremendously. An easier but more expensive way of gilding is to dedicate a small frying pan, stainless steel, or Pyrex-type glass container that can be placed directly onto a hot-plate or other heat source. The plate and enough solution to completely cover are heated until gilded, following the instructions above.

Washing: Once gilded the plate should be washed for five or more minutes in slowly moving tap-water. After washing in tap water, allow the plate to sit in distilled water for a few minutes before drying. If you don’t gild you may want to consider adding a bit of Photo-Flo or other drying aid to reduce drying marks.

Drying: Remove the plate from the distilled water, and holding it at an angle, use the hot air from a hairdryer to push all of the water to the end of the plate, where it can be soaked up by a rag or paper towel. Careful not to touch the plate with the dryer!

Mounting: Once dry immediately mount the plate behind glass using a high-quality pH-neutral tape. A thin matt between the glass and the plate’s surface will prevent the glass from scratching the plate. Once mounted, keep your Daguerreotype dry and out of direct sunlight, and it should outlast any of us.

Secure the Shadow
‘Ere the Substance Fade
let nature imitate what nature has made


Suggested Readings and Research Resources

  • Daguerreian Annual (Daguerreian Society, Pittsburgh, PA. 1990)
  • Hill, Levi L., Treatise on the Daguerreotype (1850)
  • Humphrey, S.D., American Hand Book of the Daguerreotype (1858)
  • Nelson, Ken. A Practical Introduction to the Art of Daguerreotypy in the 20th Century. (Arizona State University, Tempe, AZ 1977)
Scientific Studies:
  • Barger, Susan and William White, The Daguerreotype, 19th-century Technology and Modern Science (Smithsonian Press, Washington DC. 1991)
  • Pobboravsky, Irving. A Study of Iodized Daguerreotype Plates. (Rochester Institute of Technology, Rochester, NY 1971)
Image credits
  • Image 1: Daguerreotype Portrait of Louis-Jacques Mandé Daguerre by Jean-Baptiste Sabatier-Blot, 1844
  • Image 2: Truper 6" Bench Grinder with Spindles and Buffing Wheels by Jason Greenberg Motamedi, 2006.
  • Image 3: Fuming Box Diagram (Motamedi, ibid)
  • Image 5:Amberlith Mask (Motamedi, ibid)
  • Image 6: Glass Spirit Lamp, Bland & Long Photographic Apparatus and Chemical Preparations, 1856
  • Image 7: A Nice Meniscus (Motamedi, ibid)

Camera Equipment: I am using relatively modern equipment, most of which was purchased second-hand.

Camera: For images 5×7 or smaller I use a modern 5×7 field-camera. For full plate images I use an 8×10 field-camera as well as a traditionally designed daguerreotyping camera fitted with a period lens.

Lenses: Due to the Daguerreotype plate’s low sensitvity very fast lenses are important. If you plan on portraiture you should try to get as fast a lens as possible. I have found the Schneider 150mm f/2.8 Xenotar to be the best compromise between speed and sharpness. The Dallmeyer 8" f/2.9 Pentac, while a mediocre performer, is an affordable lens. Do not be tempted by the cheap surplus Kodak 7" f/2.5 Aero-Ektar, they are useless for Daguerreotypy due to the brown staining of rear element. I would also recommend considering Petzval portrait lenses.

Plate holders: For 5×7 and smaller I use Linhof 4×5 and 13x18cm double-sided glass plate holders, which use a clever pressure plate to make sure the plate the proper distance in relation to the plane of focus. I have a number of adaptors for these holders to I can use them with 1/4 and 1/2 plates. For whole-plate I use a Graphic 8×10 plate-holders with reducing adapters.

Accessories: Due to insensitivity to red and yellow, it is not possible to directly meter with daguerreotypes. However, I use 1° Pentax digital spot-meter to get an approximate reading, and adjust the exposure according to experience. A compendium lens-hood should be considered a necessity, as they reduce flair, a serious problem with fast lenses.

Chemicals and Lab Equipment:


Plates and Platers:

Daguerreotyping Equipment:


  1. Posted August 22, 2010 at 10:54 am | Permalink

    Great! thank you for sharing this information!

  2. mark welling
    Posted November 3, 2013 at 2:55 am | Permalink

    I have a large oval picture that appears to be on lead and it has a felt like serface. its not exactly a photograph, but its also not a painting. the subject is of a man in a suit. its well over 100 years old. can you tell me what I have exactly?

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