Demonstration: The Effect of a Water Spot Remover on a Hydrophobic Coating

[kevincwelch]

About a week ago, I had a really unfortunate situation occur to me when I used a water spot remover on my hood. I used this specific water spot remover because I did not want to have to break out the hose and rinse the hood like one has to do when using CarPro Spotless. I read the instructions, but I did not pay close attention to the warnings which clearly state a booster may be required to restore the hydrophobic properties of the coating.

A good lesson was learned. See the thread here.

So, I am trying another water spot remover, and I shall not mention the name. But I specifically used it to see if and how it affects the hydrophobic properties of the coating. Here's my experiment.

Automobile: 2013 Tesla Model S
Base coating: Gyeon Mohs
Topper: Polish Angel High Gloss

Methods
1. I marked out a section of the hood with green painter's tape. (This was actually somewhat frustrating since the tape didn't stick to the hood!). Here's the layout of the section relative to the rest of the hood.





2. For demonstration purposes, I sprayed this section and the surrounding section with distilled water to demonstrate the beading properties of the coating. The first picture is from the reference point. The second picture is a close-up of the section demonstrating the beading.


Reference point - beading


Close-up - beading




3. The section was dried with a plush MF towel. For demonstration purposes:



4. The section was then liberally sprayed with the water spot remover. As you can see, there is a little overspray, but the area was reasonably controlled as far as receiving the water spot remover.



5. As instructed, the water spot remover was immediately wiped away.



6. The hood was then resprayed with the distilled water. The first picture is the reference point. The second picture is the close-up. The third and fourth pictures are outside the application area with unadulterated Polish Angel High Gloss.

Reference point - beading


Close-up - irregular beading


Close-up - tight beads outside of the application area


Close-up - irregular beads near application area; tight beads farther away from the application area


7. The tape is removed.



8. Here is a video of the sheeting test around the area in question. As you can see, the sheeting of water is pretty good outside of the area in question, but when the water hits the area that was tested with the water spot remover, there is some obvious changes in the behavior. It's not the end of the world, but it is clearly different.



9. The test area and native areas are dried. For this, I used a plush MF towel, unfolded it and dragged it across the surface of the hood. It was not buffed or dried in circular motions, etc. No patting dry. Just dragged across the hood. You can see the outlined area where the water spot remover was located. In this instance, it was harder to remove water from the test area.





10. The hood is resprayed with distilled water. Notice the clear difference in the sectioned-off area where the water spot remover was applied and the area where there was no water spot remover. This is due to the more uniform beading outside the test area and the irregular beading within the test area.




Discussion
The area was then cleaned with N914 and a prep solution was utilized. The lower section of the hood was topped with Polish Angel High Gloss to restore the hydrophobic properties. Water spot removers are a good thing. They take the work out of removing water spots that were not removed with washing -- either conventional two bucket washes, rinseless washes or waterless washes. They are the next best thing before polishing. However, it is clear from my trial and error (mostly error) with Gyeon Water Spot Remover and this present one that water spot removers do affect the hydrophobic properties of the underlying coating. Based on my mishap previously and my experiment today, boosting that area of the coating is necessary to restore the full hydrophobic properties. I say this since with the Gyeon water spot remover, I tried washing a couple of times. I tried claying. I tried using a decon. I tried everything short of polishing. The only thing that restored the hydrophobicity was laying down additional coating material.

Now, I am not saying the water spot removers actually remove the coating, but they do something to it that requires one to boost the coating. The manufacturers are good to warn us about this. Perhaps this is better than having to polish and then apply the coating, which is more time consuming.

[idriveblackcars]

Excellent test, well done. I wonder what's in the WSR that messes with the coating. And I wonder if it's all removers.

[Eldorado2k]

Great test and write up. Looks like you did a proper job in all aspects. Thanks for posting.

The water spot remover totally killed the coating.

[Marc08EX]

Great test Kevin! Thanks for sharing this. Very useful and informative.

[richy]

I'm not really surprised to see this. The water spots are usually calcium deposits that have dried onto the paint when the water evaporates. The calcium needs is basic and needs to be removed by an acid. I always recommend starting with white vinegar which is a mild acid (acetic acid). Stronger acids are going to have some kind of effect, especially depending on the strengths and weaknesses of the coating in question. I know from experience that even with a triple coat of Gloss coat on my wife's Durango, it water spots like crazy now. It is going to be removed and replaced with Feynlab Ceramic on my vacation.

[FUNX650]

Excellent test, well done.

^^^ ^^^

I wonder what's in the WSR that
messes with the coating.

I suspect that Methyl Alcohol and
Phosphoric Acid, contained in the
Gyeon Water-Spot removal product,
could be the culprits that affected this
particular hydrophobic Coating's water
behavior, in the manner thus shown.


Bob

[kevincwelch]

Given the make-up of the water spot removers, I'm now not surprised either. However, I must take to issue the various claims that either gloss over the effect of these sprays on the hydrophobic effects of coatings. For example, this is from CarPro's website regarding CarPro Spotless:

Spotless’s proprietary blend of carefully balanced gentle acids safely removes heavy mineral deposits on most vehicle surfaces, and can even be used to help maintain our CQuartz line of nanotechnology coatings.
...
May affect windscreen/window coatings and traditional sealants and waxes

Gyeon is better:

Be aware that Q²M WaterSpot might affect the hydrophobic layer of a coating.

I don't know about Duragloss #505 or McKee's.

Optimum MDR doesn't comment on its effect on coatings/waxes/sealants.

The brand I used has no comment either.



Anyway, just hoping to help others avoid the problem that I ran into.

[PouncingPanzer]

Good post.

[glfnaz]

Great study, thanks for sharing this.