The composition, concentration and temperature of the cleaning solution depend on the substrate to be cleaned and the amount and type of soils to be removed. The compounds themselves will usually be a commercial or proprietary product. The supplier should be able to provide specific details required for use. It should be noted that in some areas, phosphates and chelating compounds cannot be used due to local effluent discharge regulations. Special proprietary compounds must be used in these areas.

1. The amount and type of soils introduced to the bath.
2. The drag-out rate.
3. Maintenance procedures and frequency.
4. Concentration, chemical makeup and operating conditions.

The first two factors can be highly variable, depending on factors such as prior process chemistry, part size, part geometry and production rate. These factors, in turn, determine the third. Graham (1971) and Spring (1974) describe a number of test procedures to determine cleanliness, including the widely used "water break test" in which the surface of the metal is examined. The test is based on the ability of a supposedly clean metal surface to sustain an unbroken film of water. However, as noted by Geduld (1988), the best and most commonly used method for determining cleaner life is to operate until problems arise, dump the cleaner, then devise a dump schedule in advance of projected problems.
Knowledge and control of soil type and drag-out rate, to the degree possible, will extend the solution service cycle and permit more efficient maintenance schedules. Unit cost for a cleaner can be determined by careful collection and analysis of daily operating data such as throughput, amount and type of chemical additions, type and frequency of waste treatment costs and dump frequency.

Pollution prevention techniques that are effective in reducing process solution drag-out tend to increase the concentration of contaminants. Alkaline cleaners, unlike plating baths, are designed to remove contaminants from the workpiece and retain them in the cleaning bath. Recovery of process solution or a reduction in drag-out may actually increase the need for removal of contaminants through more frequent maintenance by decantation, filtration or other purification process. It is generally more desirable, however, to contain contaminants in the cleaning bath than allow them to be carried to process solutions further down the line. Each application should be carefully examined. Cushnie (1994) discusses chemical solution maintenance in more detail.

Often, the same cleaners and methods can be employed for other common substrates. It is essential to recognize the specific differences imposed by the material being cleaned, make any necessary adjustments and implement the extra steps required. Typical adjustments include reducing cleaning process time, lowering temperature or adding a desmutting step in an existing bath.

In some cases moderate process changes may be required. Such changes may include the use of an alternate pickle acid formula, addition of a special activation or etching step, or the use of a strike bath. Some metals, such as aluminum, require a substantially different cleaning cycle.

In general, the same alkaline soak cleaners and operating conditions used for low carbon steel can be used for high carbon steels, cast iron, high strength alloy steels, stainless steels, nickel, nickel alloys, copper and copper alloys. Zinc and zinc alloy based die castings can sometimes be cleaned, but some adjustments (lowered temperatures and short immersion times) must be made to avoid etching. Etching of heavily soiled parts may occur when the workpiece remains in contact with the cleaning solution for an extended period of time. If etching occurs, either a pre-cleaning step prior to alkaline soak cleaning must be added or special purpose soak cleaners containing little or no sodium hydroxide must be used in the soak cleaning bath. Such situations require specific methods of preparation and additional information must be obtained.