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Litho Film and Developers
by Todd Walker

METHODS FOR MAKING COPY OR DUPLICATE NEGATIVES
USEFUL IN ALTERNATATIVE PHOTOGRAPHIC PROCESSES
The following formulae are useful in making copy or duplicate negatives from an original. By the use of the various alternatives it is possible to nearly equal the quality of the original or to depart from that in a variety of ways.

Film designed for use in the graphic arts for line or halftone work is well-suited for this work. Litho film, such as Kodalith, Ilfolith, etc., are designed and generally used for high contrast ("yes/no") work.

To achieve the highest possible contrast that the Lith film is designed for, as a "yes or no" material, negative or positive, the film must be properly processed. The developer for this purpose is Kodak A-B Litho developer (or equivalent). This is used undiluted with equal parts mixed just before use in only quantity needed. It has a limited life after the combining of the A and B solutions. For each 200 ml. of the mixed developer, 100 square inches of Litho film may be processed with no loss of quality. Development time in a tray with gentle, continuous agitation is 2.5 minutes for maximum contrast at 68 degrees F., or 2 minutes at 72 degrees F.

Kodak D-19 and D-11 developers are also useful for this purpose but are not capable of as high contrast as the Litho-type developer. The manufacturers information should be followed.

If it is necessary to use the Litho A-B developer at elevated temperatures, especially when making halftone negatives, the following restrainer is very useful for with any A-B litho-type developer.

RESTRAINER FOR LITH FILM
(modified from the Kodak formula)

Sugar (or Sodium Sulfate)   180.0grams
Potassium Bromide10.0milliliters
Acetic Acid, Glacial
or
Acetic Acid, 28%		 8.75
 
31.25		milliliters
 
milliliters
Water to1000.0     milliliters

==========================================================

For high-contrast work, use the restrainer formula as follows:

Temperature:              
 
 
 
 
Development Times,            
Solution of
10 parts each of
Lith developer A & B
and 3 parts Restrainer		Development Times,
Solution of
10 parts each of
Lith developer A & B
and 5 parts Restrainer
   
75 degrees F.     3:15 minutes/seconds     ----     minutes/seconds
80 degrees F.2:30 3:15    
83 degrees F.2:15 2:50    
85 degrees F.2:00 2:30    
88 degrees F.---- 2:15    
90 degrees F.---- 2:00    
95 degrees F.---- 1:30    

Continuous tone copies and duplicate negatives:

In order to retain shadow information, a minimum flashing exposure, to provide a just-perceptible fog density at the full development time chosen, is necessary to overcome the threshold of the film.

As a general rule, the higher the contrast desired, the more critical will be be necessary exposure. The required exposure will be different with each change in the vigor of the developer.

To use such high-contrast material to make continuous tone steps, normal print and negative developers are used with the Lith film, the resultant contrast then being dependant on the time/temperature of development and the vigor and strength of the developer in the following manner. To avoid mottling and uneven development these variables should always be adjusted to give a development time longer than two minutes. Agitation should be gentle and continuous.

Maximum:     Dektol or Selectol 1:1, 2-3 minutes, progressively diluted to 1:10 at 5 minutes.
Minimum:For less contrast, D-76 1:1, or 5 minutes, or even more dilute.

It should be remembered that all the detail desired in the final print must be well above the threshold exposure on each generation in order to be available on the final print. It is far easier to gain contrast on succeeding steps than to reduce it. Earlier steps should be of less contrast that is finally desired.

The safelight used must relate to the material. Most list film is orthochromatic and requires a #1 RED safelight.

The preceding information is from a class handout in the Non-Silver Photography class, ART 444, taught by Todd Walker at the University of Arizona in the Fall semester of 1984.

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