How to tell clearcoat thickness

Defelsko PosiTector 6000 FNS1 Coating Thickness Gauge (with 3ft probe), paint gauge, thickness gage, paint meter ?

TP143 said:

I have a few related questions on clear coat thickness:

1. Is there a way to determine how thick the clearcoat on a vehicle is to know if it is safe to do another round of buffing?

2. Is there a maximum number of buff jobs a vehicle should be put through before it is likely the clearcoat is too thin for another? I realize there are a number of variables to this so it may be impossible to answer.

3. Even after performing 8-10 passes on an area, if the swirls remain can I assume I have not taken too much clearcoat and perform another 8-10 passes, if necessary? I obviously don't want to burn through the clearcoat but something tells me as long as the swirls remain, I must not be removing much, even if it means much more passes than the 6 that is generally recommended per section.

Thanks everyone!

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1. If your pad isn't turning the color of the paint then there is still clear coat to work with. It is impossible to tell how much is left without a paint thickness gauge.

2. That question is impossible to answer. As you correctly stated there are an immeasurable number of variables to take into account that would make an estimate like this not possible.

3. If you do not have a paint thickness gauge the next best tool you have is learning the history of the paint. Has it been in any accidents? Has it been repainted? How often has the vehicle been detailed or polished? Also, if you have done 8-10 passes and you are not getting the results that you want it is time to up the aggressiveness of your pad/products to expedite the process.

What machine/pads/products are you working with?

I have the answer. At least on a couple of wrecked cars that I measured at Pick-A-Part.

I measured that total thickness of the paint on several different brands of cars. Picked an area on each car that seemed the norm. That is, wasn't the thickest or the thinnest.

Then sanded off the clearcoat until I just started getting a slight amount of color. Then measured it again. Then sanded until I went down through all the color to the primer. And measured again. I was using 220 grit sandpaper on a sanding block, dry.

The Ford Clear was 20 microns
The Ford Color was 45 microns (it was a dark blue color 1988)
The Ford Primer was 50 microns thick

The Chevy Clear was 15 microns
The Chevy Color was 50 microns (it was a black color 1993)
The Chevy Primer was 40 microns

Your results may differ. Maybe by a whole bunch. I purposely picked an area that probably wasn't heavily polished or compounded due to it's location.