The wetplate collodion process

Ken Watson, a serious “wet head” shares his joy and experience of making wet plate collodions.

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

Writer and Photographer / Ken Watson

Ken Watson Winter Carriage
Ken Watson Winter Carriage
Note: Not for beginners!

This description of the wet plate process is the procedure to make a wet plate image ASSUMING that one has collected the special equipment to do the process AND that one has gathered and mixed the chemistry necessary to the process. This is not anything like going to the local photo store and buying packaged chemistry that one mixes with water. But it is not beyond most folks who are careful and understand how to accurately weigh and measure small amounts.

I was assisted in learning the wet plate process from a publication and support via email from Mark Osterman. I also have a now good friend Eric Lowe who was also learning the process at the same time. We collaborated together and assisted each other to where we became successful (wet heads).

Image right: Winter carriage: done as an experiment that arose out of discussions of “could wet plate work in the winter and at cold temps”. I think snow on the ground answered that one.

The wetplate collodion process

This process is used to make different image types: The Ambrotype, the Tintype (also known as the Ferrotype), and a negative. In fact while the first three appear to be auto-positive images they are in fact thin negatives that via the wet plate process are able to be viewed as positives.

There are four basic sets of chemistry. The collodion (wet plate collodion process ), the Silver Bath, the Developer, and the Fixer. I will place a description of these later.

To start one needs either very clean glass, a prepared tintype sheet or black anodized aluminum plate the correct size that will fit into a plate holder.

1Pour the Collodion on
For small plate sizes (5 X 7 & down) the plate can be grasped at the lower left corner between the thumb and first finger. The collodion is poured on and then off in one smooth motion to get an even coating of the plate. There are two techniques. The first is to pour a puddle in the very center of the plate and then rock the plate to move the collodion to each corner, the second is to start pouring in the upper right corner, flow the collodion down and to the left to cover the upper left and left side of the plate and finish by flowing the bottom right corner where excess collodion is poured off. If this pouring is not done in one smooth even flow there is a great possibility that there will be ridges in your image.

2Place in silver bath
Once poured and the excess collodion is drained off of a plate and it is then placed into a silver bath. This is a solution of silver nitrate and distilled water. I have seen simple trays used but to do so one needs to remain in a completely darkroom while the plate sensitizes…about two minutes. I use a vertical bath that is light tight so that I can leave my portable darkroom (something all wet plate photographers need in the field).

3Place in plate holder
After the two minutes the plate is removed, excess silver nitrate solution that adheres to the back of the plate is wiped off by a paper towel. The sensitized plate is placed into the plate holder with the collodion side facing the lens…You did remember to make sure it is truly dark in your portable darkroom before removing the plate out of the bath and into the plate holder?

4Make exposure
One then loads the holder onto the camera, draws the dark slide, makes the exposure and closes the dark slide. The exposure that seems to work well with new collodion is F11 or F16 at three seconds. Did I mention that the speed of the collodion changes over time? How about that you have no control over temperature? Your chemistry could be anywhere between 40 to 90 degrees F and you just have to make it work correctly. Can you do this with modern materials?

Depending on the temperature, one has from two to ten minutes to make the exposure and start development. Because once the collodion dries out on your plate, that area will not develop.

5The developer
My friend John pointed out that the developer smells like apple vinegar with a bunch of nails thrown in. In fact this is about what it is. Contrary to modern photography, we want to just use the minimum amount of developer. About 14 ml for a 5 X 7. Once you have the plate out of the holder ( in the Dark room again) the correct technique is to smoothly and rapidly pour your developer onto and across the plate to completely cover it in one motion. Any place the developer stops; it will deposit a silver line that will be a streak in your image. Once the plate is covered by developer (in less that three seconds) start counting seconds in your head while watching and slowly rocking the plate. The intent is to count to 15 and to keep the developer moving. By 10 you should see a definite image. At 15 pour regular stream water over the plate. If the stream is kind of brown then be sure to get some water and let it stand overnight taking the clear stuff off the top. The water stops the development.

There are two fixing methods. One is to use Hypo or Sodium thiosulfate, the other is to use potassium cyanided. The cyanide has the added opportunity of gassing ones self if you do not completely get all the developer off the plate (cyanide gas is released by the acid). Or you could just poison yourself by having some of this material on your fingers and decide you need a sandwich. I use Hypo. The are others who use Cyanide for the image “quality”. This is a hobby for me. I do not need to risk anyone’s health close to me for a hobby.

Fixing takes as long as it takes. In most cases the rule of thumb is to watch until the image clears. The milky Iodides will be removed. Then fix for another similar length of time to completely remove the “halogens”.

As with all hypo fixed materials, the more water the better for rinsing.

Once rinsed the plates are set out to dry. Some people coat their plates with a varnish, others do not. This is poured on just as the collodion was except the varnish and plate need to be at 110 degrees F for things to work correctly. Some people also paint the collodion on ambrotypes black to protect it and to give the classical black background that these images require to become positives.

Ken Watson Poudera
Ken Watson Poudera

Collodion is a mixture of Ethyl Ether, Ethyl Alcohol, nitrocellulose and trace amounts of an iodide and bromide. Almost any water-soluble version of these will work. Those combined with heavier elements allow the collodion to last longer before going bad. This is months to a year. The lightest elements in combination may only be good for a month. You will need non-flexible collodion, additional Ether and Alcohol to dilute the collodion. Ether is explosive when allowed to pool / leak out of its container. It will also put you to sleep. Mix this stuff outside. I use everclear for the alcohol.

Image right: Poudera: one of Ken’s first 8 X 10’s, with the wind blowing so hard it about blew his camera and portable darkroom over. When he set up all was calm. Taken at about 7000 ft. The “haze” comes from the fact that a lot of UV is present at altitude and sensitized collodion is very sensitive to it. Unfortunately the lens does not focus UV on the same plane as visible light. Of course using a lens from the late 1800’s for these images might be considered an added handicap.

Silver bath

Silver nitrate crystals and distilled water. Silver nitrate will turn your skin black as well as any part of your eye it comes into contact with. Be careful or become blind.


This is usually Ferrous sulfate, acetic acid and water. I have also added Pyro from time to time.

Fixer we have talked about.

I have not included detailed chemistry amounts or the places to by this material. If you have further interests there are whole forums devoted to wet plate.

Reader’s comments on the wetplate collodion process article

Cyanide & Hypo fixing
Ken is quite correct, you don’t need to use cyanide for fixing positive images, ambrotypes and ferrotypes, produced by the wet plate process. I am a wet plate worker here in England and I use a strong ammonium thiosulphate solution for fixing images. A ferrotype will clear in fifteen seconds.

– comment by Sean MacKenna

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15 thoughts on “The wetplate collodion process”

  1. I have that Quinns Chemical pictures book on a e-book version, that is worth of reading. I have done this same process over ten years now and there’s no turning back. Next summer I will have my dark room trike ready.

  2. Can anyone help me out by provide exact chemical composition of Collodion, Silver Nitrate, Developer and Hypo. I shall be highly obliged.

  3. ken watson, i have a related process which i would like to discuss. also henry p bosse the cyanotyp photographer is my great uncle. i am in minneapolis 4008 39 avenue south 55406 612 871 4062

  4. I wonder if anyone can help I have a collection of what I think are ambrotypes would anyone be able to point me in direction of an apraiser as would consider seeking these

  5. Hi,

    I am a photography student. Can you please tell me how exactly can I make collodion? The steps mentioned here are not clear in terms of measurement, right methods of mixing chemistry.

    thank you.


  6. I wonder if someone can help me with something I need to find out for a historical novel I am writing. If a person dropped a Wet Plates / Collodion plate into a fireplace, of course the glass would break, but what would the reaction of the collodion, the silver nitrate and the black varnish be? This particular plate is only a couple years old in the novel. My character chooses to destroy it, but i want to describe what happens. hopefully he doesn’t kill himself with the fumes. This is new Orleans in 1861.

    If you can email me as well as posting here, I would be grateful.


    Nan Hawthorne

  7. Hello I am a current student studying Art and Design and i’ve worked with dark room techniques before but this process I came across after visiting the Walter Hugo exhibition in London and I needed this wet plate technique for my final major project for university, Im a total beginner for this process and Im looking to buy the chemicals to start testing out now, i’ve got 8 weeks to finish my project and by then hopefully i’d be decent enough in producing negetives.


  8. I am the author of New Dimensions in Photo Processes, and I would like to respond to post #6 by Erin.
    The method of using Liquid Light/Rockland emulsion is relatively simple and really not a big threat to your health or the environment. The results can be stunning, as the examples in my book attest, but they are slightly different in actual appearance to wet plate.
    If you want to try it before you invest a lot of money, Rockland makes a tintype kit that includes the emulsion with extra silver (“”) and 4 small plates. You use it in the darkroom with normal black and white chemistry. Information on contacting the company is in the back of my book.
    Hope this helps.

  9. @ Malin (Admin) the book is called “New Dimensions in Photo Processes” by Laura Blacklow. You coat the tin with a matte paint spray then melt liquid emulsion and coat it on a warm sheet of aluminum and let it dry (unlike collodion). Then you expose it and develop it in a mixture of paper developer and exhausted fixer.

    Has anyone ever tried it? The images in the book are stunning.

  10. @William
    Do you mean you have a description of the process? If so, let us take a look at it.
    Kind regards,

  11. i have an early color photo process with collodion although i am not a photographer but a painter. any interested persons may contact me, i am in minneapolis minnesota

  12. i have read about a non ether collodion process perhahs in book title “alternative photographic process” but cannot find an account of it now.

  13. Nice introduction to the process. I personally use potassium cyanide as a fixer because I like the look and the fact that I do almost everything out in the field where I often have limited supplies of water. I take a lot of precautions. Both chemicals work though. No one should miss out on the fun because they are afraid of cyanide.

  14. Fascinating account. I’d be interested in any photographs of ‘Dark tents’ and ‘Portable darkrooms’ in use for an exhibition I’m bringing together for Luminous-Lint. Many thanks, Alan

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