How to remove stubborn water spot stains from your cars paint and glass

How to remove stubborn water spot stains from your cars paint and glass

4 types of water stain spots

There are different types of water spots when it comes to water spot stains and etching on car paint and car glass.  These include, 

Type I Water Spots – Mineral deposits on the paint surface.

Type II Water Spots – Imprint etching in the paint.

Type III Water Spots – Crater etchings in the paint.

Type IV Water Spots – Whitish discoloration stains on and in the paint.

Type I water spots are simply called hard water spot stains.  This means that there were dissolved minerals in the water and after the water evaporated, the minerals remained behind on the surface.  These types of water spots can normally be removed by wiping or treating the surface with a product specifically formulated to break the bond between the tiny mineral deposits and the paint and/or glass.

The other types of water spots, which include, Type II, III and IV Water Spots, all must be removed via a mechanical polishing process.  The mechanical polishing process using either a polish or a compound, will level the paint surface by removing tiny portions of the paint itself.  A person would machine apply either a polish, or like in this example, a compound followed by a polish until the top surface has been abraded enough to level the surface with the lowest depths of the water spots you’re trying to remove.

Contaminated water – the root cause of the water spot stain problems

Water spot stains in your car’s clearcoat paint finish or on the glass windows of your cars has to be one of the worst types of defects to have to remove if NOT the worst type of defect to remove. 

Why?  Because the contamination and pollution in the water that lands on your car’s paint and glass can be so corrosive that it actually etches or eats into the paint leaving not a spot ON the paint but crater etching IN the paint.  When it comes to the glass, the contamination in the water can’t etch the glass because glass is very inert or not affected by corrosive chemicals to start with but when the water evaporates, the chemical contamination left behind forms such a strong bond onto the glass that it won’t wipe off or wash off.

The damage that contaminated, polluted water causes to the paint and glass on your car is so bad, you have to ask yourself… What's in the water?

The short answer is all there’s so much industrial, commercial, and even residential dumping and run-off into our water system that even with water treatment facilities, there’s simply a lot of junk in the water.  And this is true for both city water and well water.  

Clearcoat paint is actually pretty tough.  Modern clearcoat paint is made from a catalyzed urethane resin, this type of paint is much more durable and resistant to old school single stage paints like lacquers and enamels.  When sprinkler water, or car wash water or even rainwater leaves water stains and spots on your car’s paint and glass – that’s a sure sign the water is contaminated.

 Now that we know what the problem is, and for the most part the problem is unavoidable, let’s take a look at what is required to remove severe water spot stains.

Real world example

My friend Steve called me a few weeks ago asking me if I had a product to remove water spots stains off the finish of his 2020 Lincoln Nautilus.  Steve and his wife live in a Condo here in South Florida and like most Condos, they have assigned parking spaces where according to the Condo rules, this is where they are required to park their cars.  A few weeks after moving into their new Condo and parking in their assigned parking space, they discovered there’s a water sprinkler that goes off each day at a specified time and the sprinkler sprays water all over the front of their Lincoln Nautilus. 

First inspection outside in full sun

Here’s the Nautilus as it arrived at our parking lot here at 3D in Stuart, Florida.  From this angle, there doesn’t appear to be any problems.

Overhead sunlight for inspecting the paint

Now I’ve moved over to the other side of the car, Steve told me the water stain spots were isolated to the front of the car, the front bumper, fenders, and hood as this is where the sprinkler was going off and the sprinkler water was spraying onto these body panels.

Ouch!  Kind of hurts your eyes to look at so much damage from a simple lawn sprinkler!

Second inspection using a Swirl Finder Light

After moving the car into the training garage, I used a SCANGRIP Swirl Finder Light to re-inspect the damage and took some photos to document the water spots.

Washed before inspection

As you’re looking at these water stain spots, understand this car was washed right before Steve drove it down here.  These spots are not ON the paint – they are etchings in the paint.

3D Eraser Gel

There’s a best practice in the car detailing industry that I teach in my car and boat detailing classes and also practice myself, 

Use the least aggressive process to get the job done.

In keeping with this practice, the first thing I tried to remove the water stain spots was to apply the 3D Eraser Gel to a section of the paint on the hood and then according to the directions, I let it dwell for up to a minute.  Next, I wiped off the Eraser Gel and inspected, and I was saddened, but not surprised that the Eraser Gel didn’t have any effect.  3D Eraser Gel works miracles on most water spots, but this is the exception to the rule. 

This also vindicated my diagnosis of the problem and that is these irregular, circular stains are imprint spots that have ETCHED into the clearcoat.  When you have water stain spots or etchings like these, nothing is going to simply wipe them off.  The paint will need to be mechanically polished to fix the problem. 

Performing a Test Spot

In keeping with the best practice of using the least aggressive process to get the job done, once I established a wipe-on, wipe-off water spot remover would not remove the defects, the next thing I tested was a polish. 

Compounds are More Aggressive Than Polishes

In the car detailing world, there are compounds and polishes.  Compounds are more aggressive or powerful in their ability to remove below surface paint defects than polishes.  Polishes are less aggressive than compounds.  Before using a compound, I tested a polish and while it removed some of the water stain spots, it didn’t work fast enough or effective enough to make it a viable option so next up I tested a compound. 

3D 510 Premium Rubbing Compound

Here at 3D, we are unique in the car detailing industry in that we make our own abrasive technology from raw materials.  

3D Powder after converting from raw materials

The majority of car care brands you see on the shelves of your local auto parts stores or online, all purchase their abrasive technology from a handful of abrasive companies, which means most other brands are all pretty much using the same abrasive technology or what are called powders in the industry, in their products.  Not 3D – we are unique. 

The 510 Premium Rubbing Compound is a body shop compound.  It’s formulated specifically for the needs of fresh paint environments, which are your local collision shops where you take a car to be repaired and painted after an accident.  The 510 Premium Rubbing Compound is formulated to cut hard clearcoats fast and as such it will cut any paint fast.

Doing a Test Spot with 510 Premium Rubbing Compound

Besides cutting incredibly fast, the 510 also finishes out really nice but you should always follow-up a compounding step with a dedicated polishing step.  For my polishing step I used the companion product to 510 and this is the 3D 520 Finishing Polish.   Then I sealed the paint using the 3D POXY.

In the below picture you can see the section of paint on the hood where I tested the following products, pads, tools, and steps.

Final process

Step 1:  Machine compound the paint using 510 Premium Rubbing Compound with a 3D 8” Yellow X-Cut Lambswool buffing pad on a FLEX cordless PE Rotary Polisher

Step 2: Machine polish the paint using 520 Finishing Polish with a medium, 6.5" Light Purple Spider-Cut Foam Polishing Pad, on a FLEX XCE Forced Rotation Orbital Polisher

Step 3:  Machine wax the paint using 3D POXY, which is a Montan Wax paint sealant and to apply this I used a soft, 6.5" Black Spider-Cut Foam Finishing Pad  with the 3D 8mm Free Spinning Dual Action Polisher.  

Here’s the before and after results….


The results from my Test Spot proved my process worked to the test section of paint.  After inspecting the results and validating the process I chose worked, I repeated these three steps to the rest of the front of this 2020 Lincoln Nautilus and the results came out amazing.  The paint looked factory new with zero signs of any water spot stains. 

Here’s some after pictures,

Overhead Sun Shots

While swirl finder lights are great for inspecting before and after results when you’re inside a garage or shop, it’s hard to beat natural sunlight to reveal the true and accurate results.  Here’s a few pictures showing the after results after moving the Lincoln Nautilus outside to the parking lot in the same place the original before shots were taken.

Water spots stains on glass

Steve was lucky because the sprinkler didn’t reach the front windshield or side glass windows.  If the sprinkler had sprayed the glass and left water spot stains on the windows and windshield, the process to remove the water stain spots would be the same.

When wiping and washing won’t remove water spots

If the water spots are so stout that they will not wipe-off or wash off the car paint, they likely will not wipe-off or wash off the glass either.  For cases like this you need to use GLASS-SAFE abrasive technology to machine polish the glass to remove the spots.  All 3D compounds and polishes are clearcoat safe and therefore glass safe.  

I teach 2 types of glass polishing in my car detailing classes,

  • Topical Glass Polishing
  • Sub-Surface Glass polishing

    Topical Glass Polishing

    Topical glass polishing is removing water stains ON the glass.  I teach my students to do this before washing the car.  This way, when they wash the car at the same time they will wash off any splatter from the machine polishing process.

    The below pictures were taken at the May Class, here in Stuart, Florida.

    502 pictures - See what a real hands-on detailing class looks like!  And NO CHAIRS!

    The pictures below show my class machine polishing the glass on a BMW using foam cutting pads and 3D 510 Premium Compound with cordless FLEX CBEAST orbital polishers.  Afterwards, they will wash the car.  (see the wash mitts on the convertible top).

    Sub-Surface Glass Polishing

    Subsurface glass polishing is where you are machine polishing the glass to remove wiper marks, swirls and scratches that are IN the glass.  To do this type of glass polishing you need a special glass polish that uses Cerium Oxide with special rayon pads.  Because glass is very hard, this type of polishing is done best using a rotary polisher.  You can do it with orbital polishers, but it will take longer. 

    In the picture below, my class is machine polishing the wiper marks out of a classic, 1973 MBG GT using the brand new 3D Glass Polish.

    3D’s NEW Glass Polish for subsurface glass polishing

    Here’s the final results - wiper marks and scratches removed and perfect clarity restored to an original glass windshield that’s 50 years old!

    Time for the Nautilus to go home…

    I called Steve and let him know his Nautilus was now spot-free and he is welcome to come pick her up anytime that fits his schedule.  I could tell he was excited to get his SUV back and have it looking like the day they drove it off the dealership lot.


    I’ve been detailing for over 30 years and got my start in the State of Oregon, where it rains a LOT.  So, I have a LOT of experience removing all types of water spots off both glass and car paint.  In my opinion, and experience, Type I, II, II and IV water spots are the worst kind of paint defects to have to remove. 

    The good news is, if you ever experience these types of water spots that are actually etchings in the paint, 3D offers professional grade compounds and polishes to make removing the water spot stains as safe and as easy as possible.  

    The most important thing…

    When it comes to the problem of water spots on your car’s paint or glass, besides removing them, the most important thing is to discover the root cause of the water spots and then eliminate the cause. 

    In the case of my friend Steve, they moved to a new city and when choosing a new home, they chose to purchase a house with a garage and avoid any risk of water sprinklers going off near their car.  They purchased this SUV brand new and one of the reasons they loved this Nautilus so much was the beautiful metallic ruby red color.  

    Seeing the paint covered with water spots was heart-breaking.  I’m glad they found me and contacted me, and I was able to fix the problem plus educate them on how to properly wash and maintain their beautiful, Lincoln Nautilus moving forward.  Basically, I showed them this section of how-to articles on the website and told them no matter what the topic, I probably have an article that shares step-by-step how-to instructions for cleaning and detailing every aspect of their SUV. 

    Final thoughts…

    If you’re reading this and an Internet Search Engine brought you to this article because you have water spots, fear not – just reach out to me and I will help you to diagnose, which type of water spots you have and the remedy to remove them. 

    Mike Phillips

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