Drying a surface prevents water marks

Does it work?

Supported

The trade association instructs both halves directly, naming the rinsing-water quality and the active drying. It is a technique readers actively disbelieve: drying feels like tidying rather than cleaning, and it is not.

This is a verdict on whether the technique is effective. Whether it is safe on a particular surface is a separate question, answered below.

Why it works

Tap water carries dissolved calcium and magnesium compounds in proportion to the local geology. While the water is present the minerals are in solution and invisible. As the droplet evaporates the solution concentrates until the minerals are no longer soluble, and they are deposited in place as a thin film in the shape of the droplet. Removing the water before it evaporates removes the material that would have been deposited, which is why the effect of drying is complete rather than partial. Rinsing with clean water addresses the same mechanism from the other end by reducing what is dissolved in the water left behind — which is why the trade guidance specifies the rinsing water quality as well as the drying.

Background

Water marks are treated as a cleaning problem and are almost entirely a drying problem. The mark is not dirt: it is the dissolved mineral content of the water itself, left behind where a droplet evaporated in place. It follows that the mark is created after the cleaning is finished, during the interval in which the surface was left wet — and that no choice of cleaner addresses it. The stainless steel trade association states both halves directly: use clean potable rinsing water to avoid water marks, and avoid drying marks by using an air blower or wiping with clean disposable wipes. The second half is the one people skip, and it is the reason a sink cleaned properly still looks patchy an hour later. In a hard-water area the same process repeated in the same place over months is what builds the adherent scale that eventually needs an acid, so drying is also prevention for a much larger problem.

Conditions

• More pronounced in hard-water areas, and largely absent in soft-water ones

What it does not do

• It does nothing for marks already formed, which need a mild cream cleanser or, once adherent, an acid
• The benefit is proportional to water hardness, so readers in soft-water areas will notice little
• No source gives hardness thresholds, so none can be stated

What to use instead

• Mild cream cleanser — A liquid carrying a fine soft abrasive. The trade answer for water marks and light staining on stainless steel — and not the same thing as scouring powder.
• Descaling — Dissolving mineral deposits with an acid. Effective, well understood, and the wrong answer on any surface made of the same mineral.