Spots left behind when water evaporates. Most likely white or brown in color. Caused by dissolved minerals remaining on the surface.

Coating defect: change in surface appearance due to the action of water standing on the paint film or substrate.

An imperfection in a dried paint film manifested by spotty changes in the color or gloss. Water spotting may be caused by various factors such as emulsification or the solution of water-soluble components. See Rain-Spots.