Plating Q&A: Benefits of Different Soak Cleaners

Q. There are three primary types of soak cleaners: liquid, two-part liquid and powder. Which is the best one?

A. When selecting the best cleaner for your operation, it is important to consider each type’s benefits and disadvantages. I have listed some of the important things to consider when making your selection, but it will come down to working with a trusted vendor to test your options before making a final selection. Three categories should be considered: substrate (the surface or type of metal you are cleaning), the soils you need to remove and the number of stations you have to remove the soils.

Substrate. If you are cleaning only steel parts, any of three types may be viable options. However, as you move to the nonferrous substrates, such as copper or aluminum, you begin to reduce your possible options or reduce the operating ranges in which you can control the cleaner—keeping in mind the alkalinity of the cleaner and the ingredients built in to protect the substrate. A simple powder cleaner with high alkalinity may work great for steel surfaces, but will destroy aluminum parts if not formulated correctly.

As a rule of thumb, high-alkaline cleaners work for primarily steel substrates, so any of the three may work for your application. Moderate alkaline cleaners to acid-based cleaners will work for nonferrous substrates such as aluminum, which may limit your selection process. Many varieties of cleaners will work on copper, but high-alkaline cleaners can attack or dull the copper surface. Zinc substrates generally have specially formulated cleaners, so high alkaline cleaners may not be the best choice. Therefore, a borax-based powder cleaner, or low-alkaline liquid cleaner, may be the best option for zinc substrates.

Soil. What kind of soil or soils are you removing? Heavy weld scale? Animal fat-based oil or synthetic? Laser cutting dust or shop dust? Identifying the soil you are removing is critical for selecting the type of cleaner. High-alkaline cleaners may work great for a steel substrate, but if you are trying to remove a synthetic oil or water-based oil, this is not the best choice. If you are removing multiple soil sources, the two-part liquid may be the best option to control the solution’s alkalinity content, or a one-part cleaner with a range of surfactants (or soaps). If heavy weld scale or oxidized surfaces are the primary soil, a high-alkaline cleaner, powder or liquid will work. The liquid two-part cleaner enables you to increase the alkalinity, but the surfactant package needs to be designed to attack the scale.

Number of stations. Based on your line and production flow, there may be options for removal. Ideal situations have a spray cleaner, followed by a low-alkaline stage and a high-alkaline stage, with rinses between the two stages. This combination will offer the most diversity when attacking the soils. In this case, you can use all three types of cleaners. If stuck with one tank, a liquid cleaner may offer the best combination of surfactants and ingredients to handle today’s modern soils. A powder cleaner option may also be used for a one-station operation if it fits the substrate and soil requirements: Keep in mind the time and method to mix the powder cleaner into the solution and whether the process is rack or barrel.

Originally published in the April 2016 issue.