METALWORKING FLUIDS
The importance of water quality in cleaner selection and maintenance
Stephanie Zublick, Global Strategic Product Line Manager, Quaker Houghton
In metalworking, cleaning performance depends on more than just the chemistry of the fluid itself. This feature highlights the critical role water quality plays in determining outcomes, examining how factors such as hardness, conductivity and microbial contamination can influence efficiency, surface finish and overall process reliability.
Many metalworking cleaners are water based and, when further diluted in the process water, leave a cleaner bath up to 99% water (at typical use concentrations). Due to this, the quality of the water used to dilute, rinse or make up cleaning baths plays a critical role in performance. Cleaning parts in metalworking is not just about removing soils, it also directly impacts surface finish quality, coating adhesion, corrosion resistance, wastewater compliance and overall production efficiency. Having a cleaner not properly matched to the water quality can reduce cleaner bath life, cause scale and residue, increase corrosion and promote bacterial growth.
Key Water Quality Factors Hardness Hardness is the measure of calcium (Ca2 magnesium (Mg2
ampoules. Measurements from analytical testing are typically expressed as either ppm or mg/L calcium carbonate (CaCO2
).
+) and +) ions in the water. These ions are
naturally occurring positive ions that are derived from the minerals in the ground. Due to this, geography has a significant impact on the incoming hardness of the water and will vary widely. There are analytical methods for determining the total hardness of solutions. Commonly, one of two simple methods is used in the field: either test strips or titration
22 LUBE MAGAZINE NO.193 JUNE 2026
Often, because cleaning baths are run at higher temperatures (up to 85°C), water hardness can build in a cleaning bath as water evaporates over time leaving the calcium and magnesium ions in the
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