Chemical Storage and Mixing


CPAC's chemical product line should be stored in a cool, dry environment at 50° to 80°F (18° to 28°C).

All solutions have been freeze-tested to 40°F and most withstand temperatures as low as 20° without crystallizing. Most solutions will re-dissolve upon warming and all products will re-dissolve when mixed with water. If a solution has crystallized due to clod, add a small amount of warm water. Swirl the contents until it is completely dissolved and add it to the replenisher mix.

Heat is more damaging to the solutions than extreme cold. Storage for extended periods of time at high temperatures will break down the chemistry, especially thiosulfate in the fixer and bleach-fix.

Mixed developer replenisher may be stored at room temperature for up to four weeks in a covered tank with a floating lid. Secondary chemistry (all chemistry other than developers) may be stored up to six weeks at room temperature in a covered tank with a floating lid. Developer working tank solutions will last one week in the processor with no operation. Tank solution recommendations are based on periods of inactivity when heaters, circulation pumps, rollers, belts and chain drives are not operating.

In areas of extremely low humidity (<30%), floating lids should be used to prevent excessive evaporation.


Mixing instructions must be followed carefully. Add the concentrates of replenisher mix in the proper order – they are not interchangeable. Each process solution has its own specific replinisher solution, working tank and, if needed, starter solution. Use the proper amount of water, the recommended water temperature, and the specific mix times to ensure a consistent and properly mixed replenisher.

To avoid contamination, mix the developers and secondary solutions in separate mixers. Thoroughly rinse the mixer with water before and after use. Do not walk away from your mixer- this can lead to improperly and inconsistently mixed chemistry which will be reflected in your process control and finished product.