A BRIEF DESCRIPTION OF THE WET PLATE COLLODION PROCESS

by Eric Taubman

The rediscovered 19^th century process of wet plate/collodion photography has gained a great deal of popularity in recent years.  Through a variety of workshops and instructional manuals, the process is becoming accessible in a way it wasn’t during its heyday (1850’s-1870’s).  Availability of chemicals and reproduction cameras and accessories make this a unique alternative to conventional and digital technologies.

Wet plate/collodion photography can be defined as encompassing glass negatives, glass positives known as ambrotypes, and tintypes or positives on blackened tin.  It is called “wet plate” and distinguished from the later “dry plate” because the plate cannot be allowed to dry during the entire procedure.  It is a process first introduced by an Englishman, Federick Scott Archer in the year 1851.  Much of the work of photographers like Mathew Brady, Carleton Watkins, and W.H. Jackson in the U.S., and Nadar, Gustave Le Gray, and Roger Fenton in Europe, was done in wet plate.

While wet plate/collodion photography requires a substantial commitment it is not as daunting as it may first seem.  Outlined in this article are many of the steps in this technique.  They are the rough and broad steps and are not intended to be a working guide.  We can break down the technique into eight parts.

1. CAMERA & LENS

Though original wet plate cameras do sometimes come up for sale, they are usually too fragile and impractical to use.  Modern reproductions are available as are adapted wet plate backs for modern view cameras.  One of the most well known of modern day wet plate practitioners, John Coffer, has even shown how to adapt a Brownie camera for wet plate use.  Modern view camera lenses can be used but for that swirly, distorted look many desire, a period lens is more suited and can be found on eBay. Lens manufacturers such as C.C. Harrison, Dallmeyer, Ross and Darlot are some of the more reputable makers.

2. PORTABLE OR FIXED DARKROOM

In wet plate/collodion the plate must be prepared, shot, and developed all within minutes.  A darkbox (portable darkroom) must accompany anyone shooting in the field.  A standard black and white darkroom with good ventilation is suitable for home or studio shooting.

3. COLLODION

Collodion is a syrupy like substance that permits the silver emulsion to adhere to the glass or tin.  Collodion is comprised of gun-cotton, grain alcohol and ether.  It must be iodized for use.  It is poured onto the plate and “floated” to cover the entire surface.  Collodion is not only the “glue” that holds the image onto the plate but depending on the specific “mix”, also responsible for certain image traits like contrast and tonality.  Collodion largely determines the “look” of the plates. Standard single weight glass can be purchased from a glazer or at a frame shop. It can be cut down to any desired size. Tin is more difficult to obtain and blacken (“or japan”). Many wet plate photographers have opted for a replacement which is blackened aluminum, available from trophy supply shops.

4. SILVER NITRATE BATH

Once the plate is coated with the collodion and allowed to set for some seconds, it is quickly plunged into a bath of silver nitrate for approximately three minutes.  Silver nitrate is the light sensitive solution that forms the image. The purpose of the silver bath is to make the collodion sensitive by changing the metallic iodides and bromides into iodide and bromide of silver. Great care must be taken in maintaining its purity and to avoid contact with skin and eyes

5. SHOOT THE PLATE (& LIGHTING)

Once the plate has remained in the silver bath for the required time, it is removed, wiping off the excess solution on the back (non-collodion side) and placed in the wet plate camera back (same basic idea as a sheet film holder).  The photograph will need to have been composed prior to these steps as once the plate is removed from the silver bath, there are but a few minutes to actually take the picture and return to the darkroom before the plate starts to dry.  Wet plate/collodion requires fairly long exposure times from several seconds up to minutes and so the use of period lenses of large diameter and fast speed are desirable to keep exposure times as short as possible. The exposure is made by removing and returning the lens cap.  It is at this time that an exposure time is determined based on whether a negative or a positive is being created.  In general terms, negatives require much longer exposure times to be successfully printed, than positives do for viewing under reflective light.

Wet plate is mostly sensitive to ultra violet light so daylight is the most desirable source. UV light can be found in sufficient quantities in fluorescent (balanced for daylight) as well. Tungsten and strobes are low in UV and are more difficult to work with. It is not practical to estimate film speed (ASA) with wet plate since it is not visual brightness but UV brightness that matters.

6. DEVELOP THE PLATE

the exposure has been made, the wet plate camera back is returned to the darkroom and developed.  This is done by pouring on only enough developer to cover the surface of the plate.  There are many developer formulas but they are mostly formulated to produce results suited to create either a negative or a positive.  Normally development times do not exceed 30 seconds.  The developer is then poured off.

7. RINSE-FIX-RINSE

Once the developer has been poured off, it is quickly rinsed in water, which stops the action of development and makes the plate insensitive to light.  The plate must be rinsed until the water runs smoothly off the plate. It is then lowered into the fixing bath or tray for approximately one to five minutes depending on the type and strength of the fixer being used.  There are basically two types of fixer used depending on whether a positive or negative is being created. Sodium Thiosulfate  (plain hypo) is more suited to negatives and Potassium Cyanide is more suited to positives.  Sodium Thiosulfate is often used for both since Potassium Cyanide is a potentially deadly chemical.  Once the plate is fully fixed it is given a wash of five to ten minutes and then placed in a rack to dry.

8. VARNISH

The final step involves coating the plate with a varnish made of gum sandarac, Canada balsam, lavender oil and alcohol.  It is poured on a heated plate in the same way as the collodion was poured on.  Without the varnish the plate is easily scratched and tarnished.

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These aspects of wet plate/collodion photography are a brief description of what is involved.  The best way to get started is through a workshop or private instruction.  A more challenging and time consuming way would be to learn the process by studying period or contemporary manuals.  What is really impossible to communicate in words is the uniqueness and mystery of images created by this process.  They seem to have a life of their own.