Kodak D-31 manual Squeegees, Drying, Protective Coatings

Squeegees

It is important to use an adequate squeegee where the film leaves the water wash and enters the drying section. Otherwise, residual water droplets will dry and form visible surface defects and, in some cases, cause physical sticking of the film laps. In wound-up rolls, these spots may provide places where microscopic blemishes can form. Inspect squeegees regularly (particularly blade and roller types) to make sure that they do not cause film scratches.

Drying

Drying should be uniform. The drying air should be filtered so that airborne particles of dirt or potentially harmful chemical dusts, often present in processing laboratories, will not become imbedded in the emulsion while it is tacky.

In machine processing, the recommendations of both the equipment and film manufacturer for operating conditions and processing chemicals should be followed.

In other modes of processing, the following factors are involved.

Washing Aids

Using a washing aid, such as Kodak Hypo Clearing Agent (CAT No. 146-4254—5 gal.) or Kodak Microfilm Clearing Bath and Replenisher, greatly increases both the rate and thoroughness of hypo removal during the washing step.

After fixing, the film is first rinsed to remove the major portion of hypo; next, the film is treated in a Kodak Microfilm Clearing Bath and Replenisher; then it is given a final wash.

NOTE:The use of hypo eliminators, such as Kodak Hypo Eliminator HE-1, is not recommended for microfilm because some hypo eliminators contain oxidizing agents that can contribute to the formation of emulsion blisters and microscopic blemishes.

Residual Hypo Test

The accepted criterion for adequate washing is the methylene blue method described in ANSI/ PIMA IT9.17-1998.19IT9.17-1998 also describes the silver densitometric method, which has been suggested by the Association for Information and Image Management (AIIM) as a simpler and less expensive alternative. If the silver densitometric density difference is 0.02 or less, AIIM considers that the methylene blue requirements for extended-term storage record films have been met. In both methods, a clear area of the film is tested and residual hypo tests may be run up to two weeks after processing. A simpler, but less sensitive, method is the use of the Kodak Hypo Test Kit (CAT No. 196-5847). This test gives an indication of residual hypo, but it should not be used as a measurement for meeting the requirements of the ANSI specification.

NOTE:For satisfactory residual hypo levels in films, both fixing and washing must be acceptable—inadequacies in one cannot be compensated by the other.

Residual Silver Compound Test

ANSI/PIMA IT 9.17-199819and ISO 18917-1999 contain a test designed to indicate residual silver salts in the film. Such salts are an important cause of image layer degradation in aged-processed photographic films.

Protective Coatings

It should be recognized that while lacquers and other coatings have advantages for working prints receiving hard use, they are not within the scope of the ANSI long-term storage specifications.

12 D-31 June 2002