Wet-Plate Collodion Process – Ambrotypes

Writer and photography / Alexey Alexeev

Alexey Alexeev talks us though the wet plate collodion, or ambrotype process. From history to final print.


Wet-Plate process was invented by, an English sculptor and photographer, Frederic Scott Archer in 1851. He experimented with collodion in the hope of producing a photographic negative on ordinary glass plates.

He also found that underexposed very thin negative looks like good positive being placed on a black background. Such photographs on glass with black paint on one side called ambrotypes and on metal with black varnish called tintype (or Ferrotype).

The process is rather simple: bromide and iodide salts dissolved in collodion, which is a solution of pyroxylin in alcohol and ether. This mixture poured onto a cleaned glass plate, and allowed to sit for a few seconds. The plate then placed into a solution of silver nitrate in water, which would convert the iodide, bromide salts to silver iodide, bromide, respectively. Once this reaction complete, the plate removed from the silver nitrate solution, and exposed in a camera while still wet. It developed with a solution of iron sulfate, acetic acid and alcohol in water. Then plate fixed with sodium thiosulfate. After that the plate washed with tap water. Finally it protected with gum sandarac varnish.

Process in details (Ambrotype)


To make Wet-Plate collodion ether negatives or ambrotypes you have to find:

  • Plain Collodion 4%
  • Alcohol 190 Proof (95o)
  • Ethyl Ether
  • Potassium Iodide
  • Cadmium Bromide
  • Silver Nitrate
  • Ferrous Sulfate
  • Glacial Acetic Acid
  • Sodium Thiosulfate (Hypo) or Ammonium Thiosulfate
  • Distilled Water
  • Lavender Oil
  • Gum Sandarac

You also need to buy:

  • Bottles (glass and plastics)
  • Weights
  • Measurements
  • Coffee or Lab filters
  • Hydrometer

Then you should prepare all solutions for the process.

Salted Collodion

To prepare salted collodion first of all dilute plain collodion with the same amount of alcohol and ether mixture, then add some salt of bromide and some salt of iodide (see formula below).

Photographic collodion 2%

1Take 200 ml of Plain 4% Collodion

2Add 50 ml of Ethyl Ether

3Fill with 150 ml of Alcohol 190 Proof (95o)

WARNING! Use only glass bottles and measures for Ether and collodion. You have to use lab hood or work outdoor. Collodion and Ether is flammable. Ether is self-explosive. Work with great care.

You can store it in a big black glass bottles. It stores almost indefinitely.

To prepare salted collodion you need:

  • Photographic collodion 2%
  • Potassium Iodide
  • Cadmium Bromide
  • Distilled water
  • Measure for 500 ml
  • Weight
  • Plastic glass and spoon
  • Syringe
  • Glass bottle made from dark or green glass with good seal to store salted collodion

Salted collodion formula

Part A

  • 280 ml Photographic Collodion 2%

Part B

  • 3 ml Distilled Water
  • 2 g Potassium Iodide

Part C

  • 3 ml Distilled Water
  • 1.5 g Cadmium Bromide

Salted Collodion

  • Add Part B and Part C into Part A

Salted collodion preparation

1Measure 2 g of Potassium Iodide and dissolve it in 3 ml of Distilled Water (Part B). Measure 1.5 g of Cadmium Bromide or Potassium Bromide and dissolve it in 3 ml of Distilled Water (Part C)

2Measure 280 ml of Photographic Collodion 2% and pour it in a glass bottle with good seal (Part A). Add Part B into Part A and shake very well. Add Part C shake one more time.

3Collodion became orange in color and muddy like a milk – this is normal. Place this bottle in a dark cool place until collodion became clear. Let collodion set for 1-2 weeks before use.

WARNING! Use only glass bottles and measures for Ether and collodion. You have to use lab hood or work outdoor. Collodion and Ether is flammable. Ether is self-explosive. Work with great care.

Sensitizing (Silver) Bath

Chemicals list:

  • Silver Nitrate
  • Distilled Water
  • (optional) Nitric acid

And other stuff:

  • Weights
  • Graduate
  • Hydrometer
  • Plastic or glass beaker for 1000 ml and more

Sensitizing Bath Formula

100 g Silver nitrate
Distilled water up to 1000 ml

We have to sensitize a plate with the collodion in the solution of Silver Nitrate in Water to make it light-sensitive. To make this solution you have to measure 800 ml of distilled water and add 100 g of silver nitrate. Then dissolve silver nitrate and add distilled water to make 1000 ml total.

* Before dissolve silver nitrate it’s best practice to test a distilled water. Pour 20 ml – 30 ml of distilled water in to plastic glass and add a few crystals of silver nitrate salt. If the solution became clear that is means that water is good for use but if solution turns milky that this water is bad for our purposes.

Prepare sensitizing solution

1Measure 100 g of silver nitrate and add it to 800 ml of distilled water. Dissolve it. Add distilled water up to 1000 ml.

2Check specific gravity with help of the hydrometer. Check acidity. It should be Ph 3-4. If too high then add a few drops of nitric acid.

Specific Gravity should be 1065-1080.

After you make a number of plates (let say 50) silver nitrates concentration became low and there became an Ether and Alcohol in it as well as collodion particles. So you have to “sunning” (clearing) your silver bath.
For this process you should pour your solution in a big glass jar, cover it with the paper towel and place it on a window for sunning for a week or two.

After sunning process you should filtered silver nitrate solution once or better twice. Then check specific gravity and add silver nitrate or distilled water to make it around 1065-1080.

You should know one more very important thing which about sensitizing solution. Before make first plate you have to stabilize the solution. You have to do this after preparing fresh solution or after sunning process. To stabilize the solution just put a plate with the collodion overnight. After this step you should store silver nitrate in full dark (for example, in black plastic bottle).


To make developer solution you need those chemicals:

  • Iron (Ferrous) Sulfate
  • Glacial Acetic Acid
  • Alcohol
  • Distilled water
  • (optional) White Sugar

And some other stuff:

  • Weights
  • Plastic glasses and spoon
  • Plastic bottle to store solution
  • Measured

Formula I (Normal developer)

15 g Iron (Ferrous) Sulfate
355 ml Distilled Water
24 ml Glacial Acetic Acid
16 ml Alcohol 190 Proof (95o)

Formula II (Sugar developer)

15 g Iron (Ferrous) Sulfate
355 ml Distilled Water
20 ml Glacial Acetic Acid
20 ml Alcohol 190 Proof (95o)
20 g White Sugar

Measure 355 ml of Distilled water and add 15 g of Iron (Ferrous) Sulfate. Then add other ingredients. Stir well. And filter the solution into storage bottle. Developer solution will store almost indefinitely. Actually you will use it all before it became bad.


Chemicals list:

  • Sodium Thiosulfate (Hypo) or Ammonium Thiosulfate
  • Distilled Water

And other stuff:

  • Weights
  • Plastic or glass beaker for 1000 ml and more

Formula I

200 g Sodium Thiosulfate (Hypo) or Ammonium Thiosulfate
Distilled Water up to 1000 ml

Formula II

200 ml Rapid (Ilford, Kodak, etc) fixer
800 ml Distilled Water

Sandarac Varnish

We use historic sandarac varnish to protect surface of a plate. This is heat type varnish. This means that before cover the plate with varnish you should warm it as well as varnish. You have to warm plate one more time after you pour off excess of varnish. This helps to sets the varnish layer.
Materials list:

  • Sandarac
  • Alcohol 190 proof (95o)
  • Oil of Lavender

And other stuff:

  • Weights
  • Glass jar for a 500 ml with cover
  • Storage bottle
  • Lab or Coffee filters


57 g Sandarac
415 ml Alcohol
47 ml Oil of Lavender

Measure Sandarac into Glass Jar and add alcohol and oil of lavender. Cover it. Let it sit for a two or more days.
Shake it periodically.
Filter minimum three times after sandarac fully dissolved.
You should get a pale yellow – pale straw in color varnish.

Glassware and lab stuff

1For different dry chemicals you need some lab glass and plastic jars

2You need weights. This can me manual or modern weights

3To measure liquids you need some measured


Sensitizing Tank

It’s better to use special box or vertical bath to sensitize a plate with the collodion. This vertical bath consists of wood box and glass or plastic container. Such type of box needs smaller area to stand. Moreover you can turn on light while sensitize a plate.

Plate drying rack

We have to dry plates a number of times:

  • After initial washing a glass plate
  • After final washing
  • After varnishing

It’s better to use historic drying rack for drying purpose. This is simple construction made from wood.

Camera and lenses

You have to find any Large Format camera for start to make ambrotypes. This can be either old wood or modern metal camera. But before buying a camera you should know that the size is fixed and you could not make a plate larger than the size of the camera, for example if a camera is 8×10″ your maximum ambrotype will be 8×10″ and not large.
We use rather modern cameras: metal Calumet and wood Burk and James.

Modern camera has a lot of movements. This helps to manipulate with a DOF and focus.

Actually you can use all lenses for large format camera. Just remember that to focusing on infinity you need a bellows length equal focus length of your lens. But to focus closure you need longer bellows.

First Row: Dallmeyer 3B 11″/3, Dallmeyer 4B 17″/3.8; Second Row: Kodak Commercial Ektar 12″/6.3, Industar 300/4.5

First Row: Dallmeyer 3B 11″/3, Dallmeyer 4B 17″/3.8; Second Row: Kodak Commercial Ektar 12″/6.3, Industar 300/4.5

For a portraits you need bright lens F/3 – F/4 and not less. For this purpose Patzval type lenses a very useful: Darlot, Dallmeyer, Hermagis and so on.
For Still-Life and landscapes you can use any lens which you like even modern lenses.


“Albums” (storage boxes)

To store results images you need a number of storage boxes. Usually such boxes are made from plywood or wood. Such album can hold up to 50 plates.


Plate Holder

You also need to obtain a special holder for glass plate. You can buy one or make by yourself. Just cut off a central part of usual film holder and glue plastic corners.

Process stages

Deburring and washing glass plate

First of all you need to deburring a glass. Use grindstone for this operation on each edge of the glass. Wash glass plate under tap water with soap or washing liquid after that. Rinse well and place on the drying rack. You can wash a number of plates before photo session.

Cleaning glass plate

This step is very important. You have to remove all grease from the surface. It’s best to use a mixture of alcohol and whiting for this purpose. Use proportion alcohol : whiting : water 1:1:1.

Pour a small puddle into the center of the glass and rub it with a paper kitchen towels. Then clean glass with the new paper towels. Last step is to rub a surface with the alcohol using one more paper towel. Do not touch the surface which you just cleaned.


Pouring collodion

Pour a good puddle of collodion in the center of the plate. The puddle should be not very large but not very small – about 2 cm from each edge of glass.

Then you should spread the collodion by each corner and pour off excess from the last covered corner into bottle.
After pour of last drop of collodion you have to place a plate in vertical position lower the pour off corner and rotate. You need to rotate a plate to avoid a lot of parallel lines on a plate.
Right after you should wait a little about 20-30 seconds. Collodion should “set”. Check it by tap the plate from a corner. Your finger should leave a park on collodion but collodion has not to be moisture your finger. Right after that you should place the plate into sensitizing bath for 3-4 minutes


Sensitizing plate and load it

Work in a darkroom under safelight.

You should put a plate with collodion layer in sensitizing bath with silver nitrate solution right after collodion has been set. Sensitizing is sufficient when the silver nitrate flows off the surface of the plate uniformly without beading or forming irregular rivulets. Upon sufficient sensitization, the originally transparent collodion film will take on an opaque creamy appearance.
Remove the sensitized plate from the silver bath. Wipe off the reverse carefully to remove excess fluid.

Hold plate by one corner in vertical position. Use paper towel for this operation.

Load a plate into special plate holder.


Exposing the plate

Load the holder into camera and make exposure. Exposure times depend on light type, light intensity, object, lens, etc. Usually for portraits we want to obtain 3-10 seconds.
Collodion is blue light-sensitive. It means that you need a strong day light or blue light. You can use Sun or a bunk of special big fluorescent energy savings lamps.


Here is an example of making a portrait in studio. It’s helpful to use a special tool for portraits known as “Posing Stand” or “Head Rest”. This is a iron tool with massive and heavy base which allow to fix a head of a sitter.



Hold a plate in one hand by a corner and pour a small amount of developer on it. You should pour enough developer to cover entire plate but not more. It’s best not to allow developer to pour off from the plate while developing. Rotate the plate and slightly rock it to allow the developer to flow over the plate.
The image starts appears after about 5 seconds. If image come up very early and very quickly it seems that you overexposed and if image come up too slow and too long that means underexposure. Total development time should be about 20 seconds for ambrotypes.
You should stop development process before shadows appears by pouring tap water onto the plate. Then wash the plate carefully.

Fixing the plate

Place a plate into a tray with the fixer. Gently agitate a tray. This step can be done under normal light. You should fix twice longer than image became clear.

Wash the plate for 15 minutes in a 3 changes of fresh water. Then rinse it with distilled water and place to drying rack.



It’s better to varnish the plate to protect a delicate surface of the collodion image. Warm the plate on alcohol or oil lamp and warm varnish as well. Cover the plate with varnish in the same way as you covered it with the collodion. Drain excess in different bottle. Warm one more time. Be careful and avoid of burning a plate.

Black the back

We have to paint back of the plate with the black color to see the positive picture. We use glossy acrylic paint for this purpose. Cover the back with two layers. Dry it overnight after each layer.

Alexey Alexeev is a photographer and researcher of alternative and historical photographic processes and the first to learn the Wet-Plate Collodion Process in modern Russia and is using it at a professional level.

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11 thoughts on “Wet-Plate Collodion Process – Ambrotypes”

  1. May I ask how to dilute the 10% 24ml gun cotton into 4% 60ml? After first mixing 18 milliliters of ether and ethanol, pour it into 24 milliliters of 10% collodion? Thanks.

  2. Do you have to use salted collodion or can you just use regular collodion and what is the difference between the two?

  3. A hairdryer can blow dust into the plate. We prefer using a flame heat the plate after varnishing (and have for 25 years). It just needs to be warm. The plate is not tempered glass, but as long as you heat the plate evenly, it works well and gives you a glossy finish.

  4. Tap water is fine for fixing and washing. Good advice with the hairdryer but I wouldn’t use a naked flame as it can crack and break glass and the sandarac varnish is flammable.

    Ethanol isn’t explosive, it’s flammable. Methylated spirits, either the regular purple variety or the purer form (IDA/IMS in the UK) is mostly ethanol but with methanol to prevent consumption. The more dangerous solvent used in wetplate is diethyl ether. This is very flammable, potentially forming explosive peroxides if inadequately kept and I always recommend to my students and other to use it all up and dispose of the rest safely.

    Likewise silver nitrate isn’t explosive either. Or flammable. You maybe confusing the flammable warning sticker with the oxidiser sticker. They are very confusingly similar. As well as being an oxidiser silver nitrate is also very corrosive.

  5. Hi, nice page, couple of things though… use only distilled water for the final wash not tap water, much better to force dry with a hairdryer or flame before and after varnishing, and if you use glass for storage bottles be mindful that breakages can be a disaster, i dont store ethanol i make my solution with the total of what i have its explosive as is dry silver nitrate crystals. flickr username silvermachine

  6. Very informative. Well laid out, expertly illustrated and explained in very fine detail.
    Bravo Kerik!

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