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Water Spotting

Last updated: December 31, 2018

What Does Water Spotting Mean?

Water spotting consists of an area of dried mineral deposits left on a surface after being allowed to air dry.

Water spotting generally causes dulling of gloss in spots or masses of spots. Spots are caused by dissolved salts and minerals remaining on surfaces after the water evaporates. This usually happens in hard water, but can also happen in mechanically softened water. Water spotting is very common with automobiles, glass and dishwashers, and can cause corrosion.


Corrosionpedia Explains Water Spotting

Water spotting can cause:

  • Paint discoloration
  • Surface etching
  • Microscopic surface imperfections

These "water spots" are vulnerable to deterioration and should be removed and naturalized as soon as possible.

Water quality has a big effect on how severe water spots can be, specifically the amount and type of minerals in the local water supply as measured by the total suspended solids (TSS) test and other mineral levels such as sodium level.

Different types of water spots include:

  • Type I water spots are merely mineral deposits on the surface left behind after water with minerals has evaporated from the surface. These deposits can often be washed off using soap.
  • Type II water spots can only be removed by 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 which looks like fading where water pooled for some measure of time. If type III water spots are limited to only the upper surface of the paint, then they can be removed by abrading the paint by hand or machine with a compound or polish.

For permeable materials, such as a drywall ceiling, water spots or stains are permanent indicators of water damage and previous leaks.

Water spotting can be avoided by drying after washing, using a shammy cloth or towel for a car and a good drying cycle in a dishwasher, or by manual drying or good drainage after manually washing dishes.


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