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The Wizard of Photography | Article

Wet-Plate Photography


Let's imagine that you're hiking with friends to the summit of a nearby mountain or hill, and you'd like to capture the excursion on film. Today, you would just need carry along a small camera — the kind that you send back with the film inside would work just fine. But what about in times past? Well, it turns out that you could have done the same 112 years ago with your Kodak camera, which you also sent back to the factory for processing (although the original Kodak camera was return to you with new film loaded).

But if you went back more than 112 years — to, say, 1880 or so — the story would be quite different.

For one thing, you'd be dealing with heavy glass plates. The camera, too, would be heavy, as well as bulky. And chances are you'd be working with wet-collodion plates, which would mean that, in addition to your camera and glass plates, you would also need to carry on your back a complete darkroom, with all its chemicals, and in your head a fairly in-depth knowledge of chemistry.

As if all of that wasn't enough, every time you decided to take a picture, you'd have to set up your darkroom tent, prepare a glass plate, then expose and develop the plate while it was still wet.

For a detailed description on how to make pictures using the wet-plate process, check out the following step-by-step instructions. When you're through, you'll know what's involved in making a collodion negative.

Step 1: Coat with Collodion
The first step in making a collodion negative begins with a solution called, not surprisingly, collodion. 

Photographic collodion is a mixture of raw cotton (which has been treated with nitric and sulfuric acids) dissolved in ether and alcohol, with a little iodide and bromide mixed in. What exactly it's made out of doesn't really matter that much, though -- in 1880 you can buy it pre-mixed. What matters is that this solution is transparent and sticks to nearly everything.

Pour the collodion onto a glass plate, then the tilt the plate until its entire surface is coated with the solution.

Then pour the excess collodion back into its bottle.

Step 2: Dip in Silver Nitrate
Now it's time to move into the darkroom (or, if you're in the field, the dark tent).

While the plate is still wet, dip it into a solution that contains silver nitrate. The silver nitrate binds with the iodide and bromide to make a silver halide coating, which is sensitive to light.

Wipe the silver nitrate solution off the back of the plate with a clean cloth.

Step 3: Plate to Camera
While still in the darkroom, insert the plate into a light-proof holder, which is constructed to fit in your camera.

Take the holder to the camera and insert.

The silver nitrate solution will drip from the holder, even when it's in the camera. This is normal.

There's a slide in the holder that covers the glass plate. Remove the slide. The collodion plate is now ready for exposure.

Step 4: Expose
Expose the plate by removing the lens cap. This will allow light to enter the camera and strike the light-sensitive collodion.

Expose the plate for 20 seconds to 5 minutes. (Exposure time depends on how fast the silver halides react to light, how much light enters through the lens, and the amount of light hitting the subject.) Replace the lens cap to end the exposure.

Reinsert the holder's slide. The holder can now be safely removed from the camera and taken back to the darkroom or dark tent.

Step 5: Pour on Developer
Remove the glass plate from the holder.

While holding the plate over a tray, pour the developer over the plate. The developer is a solution of iron sulfate and acetic acid. It turns the silver-halide grains that have been struck by light into a metallic silver.

Rinse the glass plate with water to remove the developer.

You can now take the plate out of the darkroom.

Step 6: Fix the Plate
The grains of metallic silver are still on the plate, as are the silver halide grains not struck by light. 

Remove the unexposed silver-halide by placing the plate in a tray of sodium thiosulfate, which acts as a fixing agent.

Step 7: Wash and Varnish
Wash the plate one last time in water to remove the fixing agent, then dry.

To protect the delicate image, apply a coat of varnish to the plate. Application is conducted in much the same way that the collodion was applied to the plate. 

First, heat the bottle that contains the varnish over a flame. Also heat the glass plate over a flame. When both are blood warm, pour the varnish onto the emulsion side of the plate, tilt the plate until it is fully covered, then pour the excess back into the bottle.

On the glass plate is a visible negative image. There is a dark coating of silver where light has struck the plate; the plate is clear where it was not exposed to light.

Step 8: Make a Print
To make a albumen print from a collodion negative, float a sheet of paper on a solution of albumen (egg white) that contains a cloride. Dry.

Float the paper on a solution of silver nitrate. This produces a coating of silver chloride. Dry again.

Within a printing frame, align the negative over the paper, then place both in direct sunlight. The sun will print the picture.

Wash the print in water, then tone in gold chloride. Wash again.

"Fix" the print in sodium thiosulfate, then give it a final wash.

Your print is now ready for mounting.

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