Kodak Module 9 specifications Solution Mixing, Good mixing practices

Solution Mixing

1.Use the following mixing practices when preparing processing solutions with common mixing equipment. Mix solutions in the order in which the solutions occur in the process sequence. This order will minimize mixing time and oxidation, while providing consistent results. See Module 10, Effects of Mechanical & Chemical Variations in Process ECP-2E, for sensitometric effects of contamination and solution concentration errors.

The mixing area should be well ventilated and have a local exhaust over the mixing tank to carry off fumes and chemical dust. See Module 2, Equipment and Procedures, for exhaust specifications.

Good mixing practices:

1.Observe all precautionary information on containers and packages of each chemical, and on the Material Safety Data Sheets available from the seller of the individual chemical. Footnotes with some formulas provide further precautionary information.

2.Rinse the mix tank with water, and run fresh water through the pump. Drain the tank and pump.

3.Fill the tank to the mixing level with water at the appropriate temperature, and start the mixer. Be sure the mixer is large enough to provide adequate agitation for the volume of solution desired. The starting mixing level should be 80 percent of the final volume (if a water hopper is used, take care not to over dilute the solution). Allow one minute for agitating the water between the time the mixer is started and the first chemical addition is made. This action helps remove air from the water and disperse the first chemical addition.

4.Premeasure all chemicals,* but do not combine the dry chemicals together before adding them to the mixing tank. This practice can result in unwanted chemical reactions producing toxic and noxious fumes. The formula for each processing solution lists chemicals in the proper mixing order. Add and dissolve the chemicals in the order given, and dilute the solution to volume with water. When mixing sound track developer accelerator for persulfate bleach, ferricyanide bleach, and UL bleaches, observe the following special mixing instructions.

PERSULFATE BLEACH ACCELERATOR: Mixing with high agitation for extended periods of time can result in the loss of some PBA-1 due to aerial oxidation. Mix only until all solid chemicals have dissolved.

FERRICYANIDE BLEACH: When the ferricyanide bleach is made with ferrocyanide and persulfate, the solution should be allowed to sit approximately an hour before final adjustments are made. This allows for complete reaction of the two chemicals.

*When preparing processing solutions, use photographic grade chemicals (passing the ANSI or ANSI/ACS specifications). Kodak, as well as some other suppliers, provide such chemicals.

Caution

CORROSIVE: Avoid contact with solution and vapor. Avoid breathing vapor. Wear safety goggles and impervious gloves. Store in a cool place to prevent pressure build-up in the container.

UL BLEACH: When adding Ammonium Hydroxide to the mix tank, be sure to add it below, or at the surface of the solution to minimize the escape of Ammonia vapor. Careless handling may require evacuation of the mix room.

5.Agitate the solution for a few minutes after it has been diluted to volume, to promote complete and uniform dissolution of all the constituents. The prebath, developer, stop, and final rinse should be agitated for at least 5 minutes after dilution to volume; the fixer for 10 minutes; and the bleach for 15 minutes.

6.Analyze the solution for its critical constituents after mixing. Then place the certified solution into the appropriate storage tank.

7.Carefully rinse the mixing tank and any pump used to transport the solution. Clean the mixing equipment immediately after the tank is emptied, before salts and tars have time to form. The tank is more efficiently rinsed with numerous small-volume rinses than with fewer large-volume rinses.

Process ECP-2E Specifications 9-19