How much paint are you removing.

[Superior Shine]

How much paint are you removing

How much material (paint) is removed by the various processes of finish care that we perform on our vehicles in our endeavor for that brilliant SUPERIOR SHINE.

To demonstrate how much material is removed I acquired a damaged MBZ hood from a body shop that to the best of my knowledge still wears the original factory applied two stage black base / clear coat finish.

To perform my test I borrowed a paint thickness gauge from my pal and all around swell guy Brian White (forum name-deltman) This handy little device measures the material between the probe and a metal body panel (primer, base/color coat and clear coat ) in thousands of and inch or “mils� (one mil = one thousands of and inch). It will also measure for body filler and/or evidence of a repair. If you want to buy one expect to pay $400+ for it.

[Superior Shine]

As you see in the accompanying picture, the black finish on the hood is severely scratched. The surface was also very rough to the touch.



My first reading on the freshly washed hood was 4.2 mils. Now remember that includes everything from the metal on up to the top of the clear coat. Of the 4.2 mils, the clear coat is only 1.5 to 2.0 mils thick. I can only remove .3 to .5 (.5 being the absolute max) or I run the risk of premature clear coat failure. In other words if I remove more than .5 mils I will have weakened the clear coat and eventually have a dull area on my finish. If that happens it will have to be refinished in order to repair it.

[Superior Shine]

I thoroughly clayed the test area then took another reading. The thickness was unchanged.



I then applied Dual Action Cleaner Polish with a DA set on speed six. I took a reading of the DACP’ed area and I found no change.

[Superior Shine]

The next step was to machine sand the area with Mirkas finish sander with a 2000 grit pad. A reading of the sanded area read 4.1. I then followed that with a 4000 grit pad and got 4.0.

[Superior Shine]

The 4000 grit sanded area could have easily been polished out with something less aggressive but I choose to buff it out with Diamond Cut and a wool pad. That brought the reading down to 3.9.



The hood got a buffing with Diamond cut again but with a W7000 pad this time. There was no change.

[Superior Shine]

I finished the area off with DACP applied with a DA then topped off the finish with NXT. My final reading was still 3.9. The total mils of clear removed are .3, well within the “safety zone�.

I understand that many variables can play apart in the readings I got. The same procedures performed to another vehicle may not remove as much material or possibly more.




Things such as paint hardness, pressure applied to the finish while I buffed, the number of passes with each product, etc, all come into play. But this little test hopefully will give you an idea what is going on to repair a defect in the finish.

Now it is time to clean up the mess. I made.

[Tim Lingor]

Excellent write-up, and test Joe!!!

Tim

[Bill Prentice]

Thanks

Joe

Great demo, super information...

Thanks for sharing you skills with us.

Bill P.

[RamAirV1]

Thanks for doing that test! It was very informative. Is the clearcoat thicker on a Mercedes than on American cars? Is the clearcoat thicker?

That would be the perfect hood with which to learn rotary buffer use.

I noticed the lack of orange peel on the hood too.

RamAirV1

[scrub]

Great test and info. This did bring up a few of questions.

Did you notice very much surface correction using the 9000 pad?
I'm curious how much paint correction occurred if little to no paint was removed as read from the gauge.

Can you repeat this test on a domestic body panel?
I've read that German paint is some of the hardest paint to cut/buff out surface defects.

What determines how many readings and locations to obtian readings when using the paint thickness gauge?
Knowing how I am, I'd take a reading every couple of inches and spend more time measuring than buffing!

How does that Gauge work for fiber glass body panels?
4 down 16 more to go!!

Thanks again for the test and results. Very helpful. That little gadget seems handy and easy to use.

[Mike Phillips]

Nice write-up Joe and very informative. This gives people a really good idea of what's taking place on the surface when you use these different tools for correcting paint defects.



Mike

[Superior Shine]

Thanks guys for the kind words.

Scrub -

Did you notice very much surface correction using the 9000 pad?

Yes, the wool pad left the finshes dull with swirl marks (micro maring). The foam pad slicked it out and shined it up. Maybe it worked only on 10,000th of a mil level.
I don't know the limitation of the paint thickness gauge so it maybe impossible to read what happens in less than .1 of a mil.

Can you repeat this test on a domestic body panel?

Sure, have the hood of your car shipped to me if it is American.

I've read that German paint is some of the hardest paint to cut/buff out surface defects.

That has been my experiance as well.

What determines how many readings and locations to obtian readings when using the paint thickness gauge?

Reading from different areas of the same body panel will give you a number of readings within .2- .3 of each other. I took a few readings to get an average or just an idea of what I had to work on.

How does that Gauge work for fiber glass body panels?

This paticular one only reads on metal surfaces. Other do read coatings on fiberglass and plastic but expect to pay $3000-$4000 for one of those.

[scrub]

Originally posted by Superior Shine


Sure, have the hood of your car shipped to me if it is American.

No problem if you'll handle the shipping charges!

[Rick]

Very nice write up. I haven't toyed with much wet sanding, but that gives a good idea of whats going on when doing that drastic of correction.

[gb387]

Very nice! Like all the info gives everyone a good understanding of what is going on. When you sand or apply product with a PC or rotary even foam or wool

Looks as if you could you say that the PC is removing little to no CC even with the DACP!?!? Seems the PC is very safe to use it time and time again with no worry that you are going to hurt your paint. Something that I have alway wondered.

Thanks SS!