Kodak Module 9 specifications Filters, Crossover Squeegees, Dryer Cabinet, Film Lubrication

Filters

Filters are used to remove any insoluble material in the form of solids and tars from processing solutions and wash waters. If this material is not removed, it can adhere to the film being processed, machine tank walls, rollers, lines, etc. Filters are required in replenisher lines, recirculation systems, and wash-water lines.

The ideal porosity rating for filters is 10 microns, but the back pressure of a 10-micron filter is sometimes too great to permit adequate flow unless oversize pumps or parallel filters are used. Increasing the filter area will decrease the back pressure, but also increase the cost of filters. Filters with porosity ratings larger than 30 microns will produce low-back pressure, but are of little value in removing insoluble material. Another option is using high-porosity filters in series. The high-porosity filters will slow the clogging of the low-porosity filters.

Establish and follow a definite replacement schedule for filters. Change filters every week or two, or whenever the pressure differential across the filter housing exceeds 10 psig (69 kPa).

Polypropylene, fiber glass, or bleached cotton are acceptable filter media for all Process ECP-2E solutions. Viscose rayon is not recommended for use with the developer since it can cause adverse photographic effects. Table 9-2lists acceptable construction materials for filter cores. Test all filters for adverse photographic effects before use, as described in KODAK Publication No. K-12.

Crossover Squeegees

Processing solution loss and dilution are minimized by crossover squeegees. They wipe solution off both sides of the film strand using plastic blades, air streams, vacuum, buffer plush, or other mechanical means, and direct it back into the originating tank.

A crossover squeegee should be located on the exit strand between stages of all countercurrent washes, and on all Process ECP-2E solutions. Wiper-blade squeegees* (30- to 40-durometer hardness) can be employed, but must be carefully maintained to make sure they do not scratch the film. A general discussion on the use of squeegees is in “A Review of the Effects of Squeegees in Continuous Processing Machines,” Journal of the SMPTE, 79:121-123, February 1970. Squeegee design details are given in Module 2, Equipment and Procedures.

*A description of suitable wiper-blade squeegees is presented in “Spring- Loaded Wiper-Blade Squeegees,” Journal of the SMPTE 81:742-796, October 1972.

Dryer Cabinet

Carefully control drying of processed film. Insufficient drying may lead to a physical defect called ferrotyping. If the film is over-dried, the emulsion becomes brittle and the film tends to curl or flute. Satisfactory drying leaves the film dry without tackiness one half to two thirds of the way through the drying cabinet. Allow the film to cool to room temperature before windup. After cooling, the film should have a moisture content in equilibrium with air at 50 percent relative humidity.

Either an impingement or convection (nonimpingement) dryer can be used. The impingement dryer dries film in a shorter time and occupies less space than most nonimpingement dryers. Regardless of the type, the drying equipment must produce adequate and uniform drying to prevent deformation of the film support or emulsion. Filter the input air to the dryer to remove dust particles that can stick to the film. A high-efficiency particulate air (HEPA) filter, such as the Micretain Equi Flo filter (95 percent efficient at 0.3-micron particle size) is recommended. †

Film Lubrication

Edgewax 35 mm and wider films with a paraffin-based lubricant (approximately 50 g/L). Full coat 16 and 8 mm films with a less dense lubricant such as a 0.5 g/L PE Tetrasterate solution (RP 48-1984). See Module 2, Equipment and Procedures, for formulas and details.

†A product of Cambridge Filter Corporation, 7645 Henry Clay Blvd., Liverpool, NY 13088.

9-8 Process ECP-2E Specifications