Water Staining

Last updated: December 31, 2018

What Does Water Staining Mean?

Water staining is a patch of mineral deposits formed at certain places where water evaporates. Hard water contains large amounts of minerals such as potassium, silica and calcium. Water stains and spots develop on surfaces when water evaporates and the leftover minerals accumulate, making a dull patch on the surface.

Gloss on the surface is highly affected by water staining. Moreover, these mineral deposits also have a tendency to react with the metal surface in harsh conditions and can cause cracks, pitting or corrosion on the metal surface.

Water staining is also known as water spotting.


Corrosionpedia Explains Water Staining

Water staining can cause:

  • Paint discoloration.
  • Surface etching.
  • Microscopic surface imperfections.
  • Surface roughness.

Water stains are vulnerable to deterioration and should be removed and neutralized as soon as possible.

The water quality plays an important role in determining the severity of the water stains or spots that will occur on the metal's surface once the water evaporates. The types and quantities of minerals present in the water is identified by conducting a TSS test (total suspended solids test).

There are three types of water spots:

  • Type I water spots are called hard water spots. These are merely mineral deposits on the surface left behind after water that contains minerals has evaporated from the surface. These deposits are often washed off with soap.
  • Type II water spots are those spots in which some paint gloss has been slightly removed. Such spots are removed by first leveling the surrounding paint by hand or machine with some type of abrasive compound or paint cleaner.
  • Type III water spots are primarily a stain in the paint that looks like fading where water has pooled over time. The paint and coatings are completely chipped off from the surface. This is a severe water staining condition and if not tackled will lead to leaks, holes or cracks due to metal corrosion.


Water Spotting

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