Waterspots are mineral deposits left behind after a liquid (such as water) evaporated. During evaporation, only the water molecules will evaporate. The contamination in the water will be left behind. Minerals are a very common contamination in water.
Where do waterspots form
Waterspots can form anywhere where there can be water. When washing your car, you are likely to use water. This water flows into small holes and crevices, which are not always accessible. The water on top of body panels can reasonably easy be removed by drying the surface with a quality drying towel. But the difficult or impossible to reach areas can still get water in it, and can still get wet. Which means waterspots can form.
Very common places to find waterspots are: behind door hinges, on the underside of a car, under the hood, behind the mirror in the side mirror, inside door panels, suspension parts and the underside of bumpers.
Due to the transparency of car windows, waterspots on glass are very easy to spot.
Dirty water vs clean water
Not all water will leave waterspots or other forms of mineral deposits. Water in general doesn’t just contain water alone. Water from the rain, water in the ocean, water from the tap in your house, all the water contains impurities. These impurities can be several different things, but a very common impurity in water are minerals. These are picked up during the time water comes into contact with them, which is almost every surface on earth. After the water molecules evaporate, the impurities are left behind. These are visible with the naked eye in many cases.
Waterspots free water
It is possible to rinse a surface with water without getting waterspots, by using purified water. This is water that has been purified so it doesn’t contain any impurities anymore. This type of water has different names: osmose water, purified water, distilled water, de-ionized water, filtered water and demineralized water.
Putting a filter on your tap will help to decrease the amount of waterspots, but it will not be as effective as professionally purified water.
Removing waterspots can be difficult. The mineral deposit is reasonably hard and rough. So rubbing it around would be very unwise. In some cases, the mineral is fresh and hasn’t had time to stick to the paintwork due to the protective layer. In these cases simply wiping it with a quality washmitt and proper shampoo can be enough to remove them safely. In other cases, they are a lot more difficult to remove without causing surface imperfections in the paintwork.
An explanation from Mike Phillips:
Type I Water Spots
Type I Water Spots are primarily a mineral or dirt deposit laying on the surface of paint. Type I Water Spots can be the results of minerals suspended in city water or well water that are left behind after the water evaporates off the finish. This can happen by washing a car but not drying the water off the paint or if a sprinkler goes off next to the car covering the car with water drop that are not dried off the paint. Type I Water Spots can also be dirt or pollution particles left behind after water from rain or inclement weather evaporates of the finish. Type I Water Spots can also be Type II Water Spots in that the water can leave both a deposit on the surface and an etching in the finish. Another way people describe mineral deposits is to refer to them has Hard Water spots, or spot left by “hard water.
Type II Water Spots
Type II Water Spots are actual etchings or craters in the paint because something corrosive in a water source has landed on the paint and was not removed before a portion of the paint was eaten or dissolved by the corrosive substance.
Type III Water Spots
Type III Water Spots are spots that look faded or dull and are found primarily found on single stage paints after a water source lands on and then pools on the paint and is usually left to dwell on the surface for some measure of time before it evaporates or is wiped-off the surface. Type III Water spots can also happen to clear coat finishes too but it’s not as common because I Type III Water Spot is either a stain or fading. Clear coats don’t stain as easily as single stage paints because they are not as porous or permeable. Clear coats can’t technically fade because they are clear to start with, there’s no color to fade.
Methods that can be used
It is recommended to work your way down. Not only will you start with the safest method. You will also remove a little bit each step, making it less likely that you’ll create surface imperfections on the rougher steps.
- Washing like normal – suitable for many type I waterspots
- Cleaning with acidic product (white vinegar) – suitable for more stubborn type I waterspots and some type II waterspots
- Clay the surface – suitable for both type I and type II if the above fails
- Hand polish the surface – suitable for both type I and type II if the above fails
- Machine polish the surface – suitable for all types of waterspots