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Bill Winkler

Glass Preparation for Alternative Photographic Processes

by Bill Winkler

Background: Ever since I saw my first 8x10 color transparency I have been focused on multi-layered clear images on clear backing. I have looked at everything from Physautotypes to digital images on clear backing. Upon taking my first workshop in platinum printing I became determined to print platinum/palladium/gold on glass. About ten years later, I have a method that allows consistent printing on glass, not only of Pt/Pd/Au but also a modified gum/dichromate/pigment system for adding color to my images. Here I will address only the preparation of glass for these processes.

Goal: To consistently support any photographic medium, a piece of glass must be able to support a sheet of water. Upon rinsing, the glass should be held vertically and observed for any breaks or beading of the water. The sheet of water should evaporate in one sheet. Any breaking or beading, even minutes after wetting, will lead to image breakdown during development or clearing. Here is my standard cleaning procedure for every piece of glass I use, no matter the process:

Which Side of the Glass?
Most sheet glass is "float" glass. This means that the sheets were formed by pouring molten glass over a layer of molten tin. Therefore one side will be smoother than the other. The "up" side will not have been contaminated with hot tin and will be rougher than the "down" side. I always use the "up" side. If a wet cloth is rubbed over both surfaces the "up" side will feel and sound rougher than the "down" side. This may take a little practice, but will become obvious.

Scrub: With a wet cloth and cleanser, such as Bon Ami or Barkeeper's Friend. (I use the latter).

Rinse: In flowing tapwater.

Apply: Lime-A-Way or any cleaner containing phosphoric acid. This removes inorganic contaminates such as iron.

Rinse: In running water.

Apply: Clorox Cleanup Bleach for removing organic contaminates. (May) also form a thin layer of sodium silicate, which could promote adhesion.

Rinse: In running water,

Soak: in OxiClean or equivalent. Tap water as hot as you can get it. 2oz. OxiClean to a gallon of water. 10 minutes.

Rinse thoroughly under running water.

Rinse in distilled or filtered water.

Bake dry: At least 215 degrees F for at least 10 minutes. Test one piece for beading water.

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