With some awareness and regular attention, water spots can go from scary finish-ruining problem to minor detailing inconvenience.

Understanding water spots

A water spot on a surface is one of two things:

• Mineral deposits left behind from water that has dried
• Etching, which is physical damage to the surface

Most sources of water, such as tap water, rain water, and other household and environmental water sources contain minerals (along with other impurities). Water might end up on a vehicle through a wash bucket, driving by a sprinkler, going to a car wash, or leaving a vehicle out in the rain. When not properly dried, the minerals in the water can concentrate and deposit onto the surface. This is the first type of water spot that might be found on a vehicle surface.

If these mineral deposits are left on, they can permanently damage the surface. When this happens, the surface is etched by the minerals, which is a type of surface corrosion that worsens the longer the minerals are allowed to remain on the surface.

How to identify water spots

A water spot will appear as a visible spot or grouping of spots on the surface of a vehicle when it is dry – they resemble the outline of water drops. Depending on the type of water spot and mineral concentration, they might be white or chalky in appearance. They are most easily spotted after a wash or on a clean vehicle. Visual examples can be found in the Surface Damage Field Guide.

How to address water spots

It is impossible to tell the type of water spot and level of contamination or damage there might be before attempting to remove them. Because of this, it is recommended to start with the least aggressive removal method and work up to more aggressive methods as needed if the water spot remains on the surface.

The sooner a water spot issue is addressed, the easier it is to take care of. Above all, it’s recommended to attempt removing a water spot as soon as it is noticed.

For fresh water spots

Try re-washing the vehicle or using a Quick Detailer/Waterless Wash on the water spots. 

For non-etched water spots or before it is possible to tell

If a water spot cannot be removed by re-washing or with a Quick Detailer/Waterless Wash, an acidic cleaner such as a water spot remover will be needed. Most acidic shampoos are too weak to remove water spots. For any water spot remover that is used, make sure to follow the manufacturer’s instructions and use caution while working, as water spot removers are some of the strongest chemicals in detailing and pose a risk to both personal health and the vehicle if used incorrectly.

Before buying a cleaner, check the SDS to make sure it does not contain hydrofluoric acid or any ingredients that turn into hydrofluoric acid. If you’re unsure or unable to interpret the SDS, search for the product on the Discord server and if you don’t find the information, ask.

Some stubborn water spots may require multiple rounds of a water spot remover. If water spots appear to remain even after removing the mineral contamination, they have likely been etched into the surface. As long as the mineral contamination has been removed, no further surface damage due to etching will occur and the etched surface does not need to be addressed immediately.

For surface damage due to etched water spots

Make sure that all mineral contamination has been removed by following the methods for non-etched water spots. It might take multiple rounds of water spot remover to remove all mineral contamination. If the water spots have not gone away after multiple rounds of water spot remover, then it is likely they have etched the surface and a full decontamination, clay, and polish will need to be performed to level the surface and remove the etching. Attempting to polish with mineral contamination on the surface can permanently damage paint/clear coat, therefore it is important to make sure that mineral contamination has been removed from paint before proceeding.

If left for a long period of time, water spots can etch through the clear coat of the vehicle. In these cases it will not be possible to remove them by polishing and will require a repaint.

Considerations for water spots on PPF or vinyl

The steps to address water spots on PPF or vinyl are the same as other surfaces, but the chemicals used need to be PPF or vinyl safe and PPF/Vinyl-appropriate abrasives and techniques should be used for polishing.

Water spots on other surfaces

Water spots can form on many different vehicle surfaces. The process outlined to remove them is largely the same, but material safety of the chemicals, polishes, techniques, etc. should be considered depending on the surface. Follow the product manufacturers instructions for the type of surface material, and reach out to them if it is unclear whether or not it is safe for a particular surface.

How to prevent water spotting

There are a number of straightforward ways to prevent or limit the impact of water spotting:

• Work where water will dry more slowly – such as cooler areas and in the shade
• Dry quickly, especially when using hard water, use good drying technique when washing and work quickly
• Catch drips from gas caps, mirrors, and trim pieces, or blow around them with an air gun or blower to drive water out
• Work with demineralised water, sometimes referred to as spotless or spot free water (also known generally as deionized, distilled, mineral free)
• Consider finishing with a rinseless wash
• If water spots from rain are a concern, park vehicles in a garage or under a carport – if it’s not possible to park a vehicle in an enclosed area, address the water spots as quickly as possible

The best defense against water spot damage is to catch them early and address them with a Quick Detailer or rinseless wash – as these methods can be enough to remove them if caught early and are much more gentle and safe.

The influence of beading on water spots

While coatings and sealants make washing and detailing much easier in many situations, they are one of the biggest causes of water spotting. The stronger a vehicle surface beads, the more the water becomes concentrated at a single point (or grouping of concentrated points). In addition to concentrating the minerals at these points, the water beads also focus the light (and therefore heat) more intensely, causing them to dry more quickly and increase the risk of water spotting. If there is a concern with excessive or particularly harmful water spotting issues on a vehicle, a sealant that does not bead as intensely might alleviate some water spotting, such as a carnauba based product.

Product considerations: water spot removers with or without sealants

There are two main types of water spot removers: those with a sealant, and those without a sealant.

In general, a water spot remover with a sealant can be just as capable at removing water spots as one that does not contain a sealant. Water spot removers with a sealant can make the detailing process more efficient by not requiring the application of an additional sealant after the use of water spot remover. If a water spot remover with a sealant is being used on a coated vehicle, make sure the sealant is compatible with the coating.

A water spot remover with sealant should not be used to prep a matte vehicle for coating – the sealant would be left on the surface and interfere with the coating application since matte vehicles do not undergo a polishing step prior to coating (which generally removes any sealant from the surface).