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Page Contents:
A Special Note About Potassium Cyanide Use:
Material Safety Data Sheets (MSD):
Standard Lab Practice:
Standard Plate Dimensions:
Film Holders:
Collodion Optics:
A Basic Collodion Formula:
Developers for Collodion:
Plate Prep: Tin
Plate Prep: Glass
Pouring Collodion:
Sensitizing the Plate:
Making Your First Exposure:
Developing the Plate:
Fixing the Plate:
Varnishing the Plate:
Using a Light Meter:
Troubleshooting Peeling:
Troubleshooting Comets:
Troubleshooting Developing:


A Special Note About Fixers and Potassium Cyanide Use:

Hypo (sodium thiosulphate) is an equally effective alternative for removing undeveloped silver salts from collodion film and involves none of the hazards of potassium cyanide.
Please be safe. There is no reason whatsoever to use Potassium Cyanide.

Before we go any further...If you're one who still insists on using Potassium Cyanide instead of Hypo as a fixing agent for collodion films, please recognize the hazards involved. This stuff is deadly. The following is an excerpt from an AMES research safety document regarding Potassium Cyanide. The term LD50 references the Lethal Dose required to produce a 50% death rate in a test population (in this case rats).

Potassium Cyanide Health Effects:

Acute toxicity is high.
Ingestion of NaCN or KCN or exposure to their salts or their aqueous solutions by eye or skin contact can be fatal.
Exposure to as little as 50-150 milligrams can cause immediate collapse and death.
Symptoms of nonlethal exposure to cyanide include weakness, headache, dizziness, rapid breathing, nausea, and vomiting.
Cyanide salts are corrosive and toxic.
Decomposition products of HCN and nitrogen oxides are extremely hazardous.
LD50 (Lethal Dose for 50% of test subjects) is:
KCN (potassium cyanide), 8.5mg/kg (of body weight), orally injested, rat
NaCN (sodium cyanide), 6.4 mg/kg (of body weight), orally injested, rat

The above excerpt refers to "decomposition products of HCN...". HCN is hydrogen cyanide GAS. This is released if potassium cyanide comes in contact with acids (among other things). Remember that your developers use acids as restraining agents... mixing developers and potassium cyanide is a recipe for trouble.

In closing, please consider using Hypo for fixing your plates. It's a tried and true method with minimal risks.

Now, on with the show...

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Material Safety Data Sheets:

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Standard Lab Practices

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Standard Glass Plate Dimensions
Traditional dimensions for glass plate collodion work are:

Whole Plate: 6.5" x 8.5"
Half Plate: 4.25" x 5.5"
Quarter Plate: 3.25" x 4.25"
1/6th Plate: 2.5" x 3"
1/9th Plate: 2" x 2.5"
1/16th Plate: 1.625" x 2.125"
Gem: 0.5" x 1"

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Film Holders

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Collodion Optics

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A Basic Collodion Formula

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A Collodion Developer

Here is a good general purpose ferrous sulfate developer for collodion. (and it's easy to remember!) The total volume is approximately 7.5 ounces.

In an 500 ml beaker, Pour:
  210 ml Distilled Water
  10 gm Ferrous Sulfate
Stir the Ferrous Sulfate into the distilled water until it's completely dissolved, then add:
  10 ml Acetic Acid
  10 ml Alcohol

Mix thoroughly, and filter the solution into an 8 ounce bottle.

To better understand what the developer is actually doing and to make the recipe a little less mysterious, let's look at the function of each component individually and see what it does.

The first ingredient is water. This is merely the solvent which allows the various chemicals to blend and provides a measure of dilution.

Next on the list is Ferrous Sulfate. This alone, is the developing (or reducing) agent. It acts to reduce the exposed metallic salts (silver iodide) into metallic silver. Ferrous sulfate is an aggressive developer, and by itself, without dilution or restraining, would begin reducing silver salts that had not been exposed by the image forming light, thus resulting in a fogged plate.

The action of the developer can be restrained by the addition of an acid. The usual choice for this is acetic acid, although other acids (such as Nitric Acid which tends to brighten the surface of the metallic silver deposits) can also be used. Although if the amount of silver iodide in the collodion is too little, or if insufficient silver nitrate is present on the plate at the time of development, the use of nitric acid may prevent the deposition of metallic silver in various regions of the plate.

Another commonly used restraining agent is sugar. When dissolved into the developer, the sugar acts to thicken the fluid slightly, making it more viscous and thus slowing the physical agitation of the developer on the plate, thereby slowing the rate at which the developer comes in contact with the exposed silver salts. If you'd like to see this in action, the next time you make a cup of hot tea, make two, one with sugar already dissolved in the water before inserting the tea bag, and the other with just water alone. You'll notice the tea using water alone colors up quicker than that which had the sugar dissolved in it.

Alcohol can be also be added to the developer as necessary to act as a "wetting agent" if it is found that the developer has an oily appearance when poured onto the surface of the plate.

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Plate Prep for Tin

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Plate Prep for Glass

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Pouring Collodion

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Sensitizing the Plate

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Making Your First Exposure

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Developing the Plate

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Fixing the Plate

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Varnishing the Plate

The traditional method of finishing a plate is to varnish it after it's thoroughly dry. This is done by carefully pouring a sandarac varnish over the warmed plate and drying it over a lamp or heater. It's fairly delicate work and provides all sorts of opportunities to ruin a great plate. With this in mind, always always always (did I say always?) scan your plate before you varnish it. That way you at least have a digital back up. In spite of the potential difficulties in learning the techniques of varnishing plates, it is a proven technique for sealing and preserving collodion images. It's worth the effort to master these skills.

Now, getting back to varnishing...First, pour a small amount of varnish into a pouring bottle and warm it in a beaker of water. Warm your plate over a hot plate, alcohol burner, or kerosene lamp (not hot! if you can't touch it to the underside of your wrist, it's too hot) Keep the plate moving so it heats evenly. Pour the varnish as you would pour collodion, beginning with a circular pool of varnish in the middle of your plate, then tipping the plate to the left, then away, then to the right, then finally toward you and draining the excess back into a second bottle which you will then filter again before reuse. Blot the edges of the plate on a clean paper towel, while rocking the plate toward and away from you to remove any excess buildup of varnish from the edges of the plate. Heat the plate again over an alcohol burner until the varnish has set. Place the plate in a drying rack and allow it to cure for at least 24 hours.

Now, if you're not that concerned with traditional methods, and you're feeling a little experimental, you may want to try spray polyurathane. I should offer a disclaimer here: these materials have not been tested over time, and may, or may not, cause harm to the image in years to come. There have been anecdotal reports of peeling or flaking of the collodion many years after it's been coated with paint, but I'm unaware of the details regarding the materials used in these cases. There are some differences between brands of polyurathane and the best I've seen to date is Minwax Premium Spray Polyurathane. This seems to level uniformly, provide the smoothest coat, and produce a beautifully glossy finish. As with traditional varnishing, you need to warm your plate to drive off any moisture that may be in the collodion. If you don't do this, you will see cloudy white areas show up in your image. Apply 3 or four very light coats crossing the plate in various directions. The idea here is not to leave a spray pattern in the finish.

If you're shooting clear glass ambrotypes, you have yet another method available. Black spray paint. Eeeekkkk!! Black? Yes, black. The beauty of this is, you'll be viewing your image from the glass side of the image which provides a pristine perfectly smooth and glossy surface to the front side of the image while the black paint now does double duty by sealing and protecting the collodion while it forms the black backing that you would normally mount behind the image. The advantages here are several: you no longer have to worry about the slightest bit of dust showing up in your finish, keeping a glossy texture is not important at all, and you've eliminated the air gap between the image and the black surface, thereby eliminating reflections between the glass and the background which gives you a much deeper black in the shadow areas of your image...yummmm!!! It really makes the image pop. Secondarily, you may even want to experiment with different colors of paint! If you do this, remember to stay on the dark side, since lighter tones will make your image appear as a negative. But this could be interesting too, depending on what you're looking for.

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Using a Light Meter

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Troubleshooting: Collodion Peeling or Lifting from the Plate:

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Trouble Shooting - Comets:

Comets are streaks that show up on the plate that can originate from either chemical or physical causes.

One type originates at a point or grain of contamination in or on the collodion film. As the plate is dipped into the silver nitrate, this contamination is drawn away from the original point by the relative motion between the silver nitrate solution and the plate, forming the comet's swept tail.

A second, more common type of comet is the result of undissolved ferrous sulfate (from the developer) touching down on the collodion when the developer is flowed across the plate. This undissolved (concentrated) developer immediately fogs the film wherever it comes in contact. The tail extends in the direction of developer flow

To minimize the possibility of forming comets, filter your developer, and be sure to handle the collodion gently. Avoid mixing or shaking the collodion prior to use. Allow any particulate matter to settle out of the solution before using.

   
  This is a magnified view of a comet that appears to be a physical obstruction imbedded in the collodion film. Notice the bumps sticking up above the collodion surface.   This is a magnified view of a different comet that appears to be chemical in nature and one that is located within the collodion film and not distorting the surface of the film as seen in the first image. Notice the central "grain" that's resides in a very well defined region completely devoid of developed silver.


 
  This is a magnified stereo image of a comet protruding above the collodion's surface, taken in reflected light.


 
  This is a magnified stereo image of a comet caused by a chemical grain within the collodion film, illuminated by transmitted light.


 
  This is the same comet as shown above, illuminated by reflected light.

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Trouble Shooting - Pouring Developer Directly onto One Spot:

Development is both a physical and chemical process. The chemical part of the process involves reducing the exposed silver iodide in the collodion film into metallic silver through the action of the developing agents. The physical aspect of the development comes into play because the presence of free silver nitrate is necessary for the chemical action to occur. An aqueous solution of free silver nitrate normally coats the surface of the plate after sensitizing it. This is the "Wet" in wet-plate. Because it's a liquid, it can easily be moved around on the plate.

The reason we use as little developer as possible during development is to keep the concentration of the free silver nitrate high enough to do it's job, and bring out an image. If, the free silver nitrate is washed away by physically "splashing" the developer onto the plate, the image won't form properly.

The most obvious way of pushing this free silver nitrate away is by pouring the developer directly onto the plate in one spot, causing the stream of developer to strike the plate with some force. This effectively pushes the free silver nitrate away from this spot, producing a somewhat circular region that has little or no image.

   
  This image was produced by pouring the developer directly onto one spot on the plate. Artifacts like this are typically between 1/2 and 1 inch in diameter.


  This is the same artifact, but the speed of the pour was much greater. Notice the extra bands surrounding the central portion. These were caused by waves and ripples as the developer "splashed" away from the center. This artifact is about 2 inches in diameter.


Errors like this, can be corrected by allowing the developer to flow as smoothly and evenly as possible across the plate.

Trouble Shooting - The Hazards of Over Development:

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