Question about microns of paint

efnfast · 11-05-09, 07:00

I was able to measure my paint today and found that it has (roughly) between 30 and 40 microns of clear, and between 350 and 400microns of basecoat.

Any ideas how these numbers stack up against production paint jobs? For example, twice the amount of clear you'd normally find, and twice the basecoat? I see averages of around 100-130, which I've always assumed are clear+base combined together, but figured I'd ask to make certain.

Scottwax · 11-05-09, 08:25

I was not aware of paint thickness gauges that can differentiate between types of paint on a car. Typically though, the color coat is very thin since you have the clear coat to protect it.

efnfast · 11-05-09, 09:13

It was a Positector that gave several readings, like this one

If it matters it was a fiberglass car - my friend said it could differentiate between the base layer and the clear.

I was just curious of others' experiences on here - probably limited because those fiberglass PTGs are pretty bloody expensive.

Setec Astronomy · 11-06-09, 03:22

Sorry I don't have this in microns, a typical factory paint job is about 4-6 mils thick. You've got ecoat, primer, color, and clear. The clear is 1.5-2, making it the thickest portion.

EDIT: There's a cross-section on this page: Polishing Paint to Perfection . Here's another that talks about thicknesses: "Electronic Paint thickness gages- what they are and why you need*them" - Auto Detailing Articles and Tips by Kevin Farrell - Comprehensive Resources for Professional Auto Detailing Business Owners and the Automotive Detail Industry

Here you go, in microns: paint

EDIT EDIT: Circular/ Rotary Polishing Guide: remove swirls, scratches, & oxidation with a rotary polisher. foam pads, backing plate, lake country, professional, ...still can't find the one I was really looking for

gmblack3a · 11-06-09, 05:02

Quote:

Originally Posted by efnfast

I was able to measure my paint today and found that it has (roughly) between 30 and 40 microns of clear, and between 350 and 400microns of basecoat.

Any ideas how these numbers stack up against production paint jobs? For example, twice the amount of clear you'd normally find, and twice the basecoat? I see averages of around 100-130, which I've always assumed are clear+base combined together, but figured I'd ask to make certain.

I too have an advanced 200 PTG.

On a 08 vette in Crystal Red Metallic.

Total thickness on the hood was 5.0 mils or 127 microns.

Base was 1.5 mils or 38.1 microns.

Clear was 3.5 mils or 88.9 microns.

On a few different plastic bumpers, I have found approx the same. The base is usually 30-35% and the clear is usually 65-70 % of the total thickness.

MuttGrunt · 11-06-09, 05:21

Speaking to Defelsko directly, as well as Elcometer/Highline directly, the are many issues with these ultrasonic coating thickness guages.
First off, they were never designed for use on automotive paint. To be used on automotive paint can therefor lead to big drops in accuracy. If you think about how sonic waves move (as they move over distance, they spread) you'll realize the problem of trying to take readings off of a curved surface, you'll at least understand in part.

A Defelsko representative told me that while it can still be used, one issue likely to come up is you won't get readings aside from the clear-coat and everything else. In short: you'll get a reading of the clear-coat, but the base coat, primer-sealer, primer-surfacer, and E-coat/self-etching primer will likely be grouped together as there isn't a big enough difference in the density in those layers for the tool to tell a difference in them.

This will help to show you that even though it seemed to read differently, you're clear-coat is, like others pointed out, still going to be the thickest layer. Everything other than the clear was just lumped together.

To other pro's reading this, take into account that with a drop-off in accuracy, it's still better to have 80% accuracy and have an idea then to go totally blind.
-Marc

Setec Astronomy · 11-06-09, 05:34

Quote:

Originally Posted by MuttGrunt

Speaking to Defelsko directly, as well as Elcometer/Highline directly, the are many issues with these ultrasonic coating thickness guages.
First off, they were never designed for use on automotive paint. To be used on automotive paint can therefor lead to big drops in accuracy. If you think about how sonic waves move (as they move over distance, they spread) you'll realize the problem of trying to take readings off of a curved surface, you'll at least understand in part.

Are these ultrasonic, rather than eddy current? Forget automotive, eddy current testers have problems with curved surfaces, or any surface different than what you calibrate on. All of that has to be factored into how you interpret the results.

MuttGrunt · 11-06-09, 05:55

Good question Setec, and I believe all coating thickness readers that are meant for wood/composite materials are ultrasonic so they can read on things other than metal

Accumulator · 11-06-09, 09:56

Oh you guys are killing me with all this talk about differentiating ETGs

Street5927 · 11-06-09, 10:20

1 mil is approximately 25.4 microns. A new car has a basecoat of approximately 4.0 mils (101.6 microns) to 6.0 mils (152.4 microns). The clear is approximately 1.5 mils (38.1 microns) to 2.2 mils (55.8 microns). For a new car, you should see variations from 5.5 mils (139 microns) to 8.2 mils (208.2 microns). You should remove NO MORE than 25% of the clear or .375 mils (9.5 microns). I always go on the basis of the lowest possible amount, that being 5.5 mils (139 microns), less the 25% clear or 129 microns, you know that you are very close to polishing/sanding through the clear. In your case, it seems as though your clear is thicker than your basecoat, which makes me wonder if your machine is working properly. As said before, I don't know of any paint guages that are able to differentiate between the clear and base.

On the other hand, your machine is converting mils to microns correctly. If you take your mils and multiply by 25.4, you will get micron readings.

1.5mils (base) x 25.4 = 38.1 microns
3.5mils (clear) x 25.4 = 88.9 microns

If you have a guage that only measures in mils, just take your mil reading and multiply by 25.4 and it will give you a micron reading. Hope this helps

efnfast · 11-06-09, 10:47

Quote:

Originally Posted by Street5927

In your case, it seems as though your clear is thicker than your basecoat, which makes me wonder if your machine is working properly. As said before, I don't know of any paint guages that are able to differentiate between the clear and base.

So with the positector 200 if there are 3 readings on the lefthand side of the screen say, for example, say,

1 - 45

2 - 400

3 - (blank)

How would you interpret that?

For what it's worth, it's a fiberglass car and all parts were handsprayed (i.e., this is not a production paint job). The paint is definately thick because if, for example, I lift up the hood before it was painted, and after, it's noticeably heavier after paint.

Street5927 · 11-06-09, 10:51

Quote:

Originally Posted by efnfast

So with the positector 200 if there are 3 readings on the lefthand side of the screen say, for example, say,

1 - 45

2 - 400

3 - (blank)

How would you interpret that?

For what it's worth, it's a fiberglass car and all parts were handsprayed (i.e., this is not a production paint job). The paint is definately thick because if, for example, I lift up the hood before it was painted, and after, it's noticeably heavier after paint.

I would check the manual to see what the readings are, however, I think it is unusual to have thicker clear than base.