Analog Photography—Chemicals and Processing

Winter Quarter 2022, Kalamazoo College

Richard Koenig, Professor

 

 

Light Sensitive Materials and Basic Chemistry

 

Silver halide is the material in both film and paper that is sensitive to light.  It is metallic silver in chemical compound with a halogen (iodine, chlorine, or bromine).  It is also called silver salts. When light strikes the silver salts it reduces, or breaks down, some of the salts to their components—metallic silver and the halide.  It is this metallic silver that will form the image. At this point, with the film exposed to light, we have a latent image: a slight change, not visible to the eye, but we can build on it.

 

á                Developer—The main component of the developer is a reducing agent.  It further breaks down the silver salts in the exposed area. This increases the metallic silver around the latent image, building it up, making it visible. The halide in this exposed area combines with the developer and is therefore removed when we discard the chemical.

 

á                Stop Bath—Like its name says, this bath stops the development. Developer is alkaline while stop is acidic—usually a diluted form of acetic acid. It neutralizes the developer, making for more accurate developing times as well as preserving our next chemicalÉ

 

á                Fix—At this point, the unexposed (and therefore undeveloped) silver halide particles are still on the film. These are sensitive to light and must be removed. Fixer contains a silver halide solvent, which will dissolve and remove it out of the emulsion. Now only the portion of the negative that was exposed has silver remaining. This area is called density.

 

á                Wash—The remnants of fix and silver halide must be removed or it will deteriorate the film or paper. Simply washing with water will do this but using a washing aid (ours is called hypo-clear) prior to the wash saves water and does a better job.

 

 

Development—Generally Speaking

 

The development phase is the most critical step here: what are some variables that can affect your success?

 

á                Time—Look at chart for development time for your particular film (on the bottle of Edwal FG7), allow for pour time.

 

á                Temp—Again, the developer temperature is the most important: 70o. Other chemicals should be plus or minus 5o F (or room temp). Beware: adverse wash temperature can cause reticulation.

 

á                Agitation—Invert (abrupt but not violent) five seconds every 30 seconds while in the developer. Remember to tap tank after each agitation to dislodge air bubbles.

 

 

Processing Film

 

Put film on reel (in total darkness)—remember to keep lid on until after fix!

 

 

Developer

Dilute Stock Solution (Ilford Ilfotech HC) 1:7 (or 2:14)

See chart on wall

Stop

Water Rinse

 

1 minute

Fix

Straight from bottle under sink, when

done, recycle (pour back into bottle)!

5 minutes

Rinse

Fill and dump with water a couple

of times, remove lid

1 minute

Inspect

Open the tank and look at the film:

If it looks milky or really purple, then

put back in fix for several more minutes

 

Full Wash

Fill and dump with water (with lid off)

 

15 to 20 times

Photo-Flo

Mix 2.5 ml (use graduated eyedropper

per 16 oz water, discard

1 minute

 

 

Hang film to dry—pull film directly from photo-flo and hang up very wet. If you use the film dryer, do not turn on immediately—allow the photo-flo to sheet off the film for ten minutes first. When dry (about 20 minutes using dryer, an hour without) place on light table, cut into strips that are 5 or 6 frames in length (depending on the type of negative sleeves youÕve purchased), and place in sleeves.

 

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