Water Spots on Stainless? Improve Blowing Process

Q. White spots appear on our stainless steel parts the day after cleaning with Alconox detergent. Right after we clean them, they are dry and visually clean. So, is this next-day residue from the Alconox detergent? If not, can you tell us why this is happening?

A. It is quite unlikely that visually clean parts have Alconox® Powdered Precision Cleaner residues suddenly appearing the next day.  In addition to Alconox powder being very free rinsing, any residue that did not get rinsed for whatever reason, would be visible fairly immediately following said rinse.

Most in similar situations, even though the parts appear “dry and visually clean,” find that the spots are from water. If even a  few drops of rinse water are left on the parts, then when water evaporates, it concentrates the trace salts and leaves calcium, magnesium and iron deposits. These often appear in characteristic sets of white ring shapes, i.e. water spots.

This often happens because of a less than optimal blowing process after rinsing. In applications where a rinse tank is used, residue buildup can occur over time.  This can eventually lead to water spots, especially if the blowing dry process is not complete. The process can also be improved by using larger dip tanks, changing out the rinse water more frequently, or by using counter-flow cascade, overflow rinse tanks.

In short, using deionized water for a final rinse (such that you eliminate mineral deposits in the first place) and improving the blowing off process so that no drops of water remain are great first steps here in eliminating water spots.   

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