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Writer / Ken Watson

The wetplate collodion process

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

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).

The 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.

6Fixing
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.

Chemistry

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.

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.

Developer

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 process

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