WHAT ARE WATER SPOTS?
Simply put, a water spot forms from the minerals that were suspended in the water droplet as the water dries and evaporates. Depending on the source of the water and where it had been before drying, you can see any number of things cause the actual spot.
Ground water is the most common culprit. The water from a mis-aimed sprinkler, or the water used from your hose, is full of minerals. The type of mineral and concentration varies from region to region, and based on how 'hard' your water is, you may see more severe spotting. Rain water typically carries a different type of contamination. As that little droplet fell through the air, it picked up airborne pollution as well as dust or dirt. Plus, if the water ran off of a tree or nearby roof before landing on your car, it took some of the contamination from those surfaces as well. Road water would be the very dirty water that is splashed up behind your wheels or all over the lower sections of your car when driving in wet conditions. It’s almost impossible to know what is suspended in that water, but it contains all sorts of very nasty dirt, chemicals, oils, and other road grime.
WHAT IS BONDED MINERAL CONTAMINATION?
Bonded minerals are essentially a more severe form of water spot. When mineral concentrations are higher, or a car is subjected to lots of ground water drying on the surface (such as sprinklers that hit a car every morning), water spots can become bonded minerals. These are a little more difficult to deal with, as they form hard bonds with the clear coat that make them harder to remove. Once removed, bonded mineral contamination can sometimes leave those areas looking dull or even pitted to a small extent, which would then require polishing to fix.
WHAT IS ETCHING?
Etching is the worst case scenario in the progression of water spots. Etching typically occurs from water that is baked onto the surface in direct sunlight or high heat. It is also prevalent with acid rain or ground water with high levels of chlorine. Etching can be minor to severe, with the most severe kind requiring very aggressive means of correction - potentially wet sanding in extreme cases. Etching is a circumstance where the water spot has physically 'eaten' its way into the clear coat, so that it sits at a lower level than the surrounding surface.