[PTG] Questions

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WilliamG

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Hello !

First, I want you to know that I'm not American or English and I wasn't very good at school, this is why I'll do my best to correctly right in your language.


I also want you to know that I've been searching before asking here my question, but all the time I never get the answer which I can be sure for 100%,


So, I have a paint thickness gauge, a simple and an easy one (PD8).
I had to remove deep water spot and medium scratch on a friend's car which is BMW M3 E46.
I always work safe, so after the washing/claying/drying steps I took my measurements with my PTG and the average clearcoat was 0,3 MILS. I thought that my PTG need to be calibrate, but I did and the measurements were the same.. I told my friend that I cannot do anything which contains abrasives because the thickness of the clearcoat on the whole car is to thin. ( ?? )



Months after, my friend told me that he came to professional detailer , he told him that he can do it easily and without any problems..
I ask about the thickness of the clearcoat and he told my friend that it doesnt matter and he doesn't need to take mesure, for example he said that when he works on LOTUS car he cannot take measure because of the composite and it is not a problem...


[ I took measure on doorsjamb and I found 2,9 MILS ; I also try my PTG on another car and it seems like working correctly ]



I'm lost and stupid, I'm feeling like I missed something or cannot understand something like when you're a kid...


This is why I need your help, I want to understand 3 things :



  • When a detailer works on car which is made of composite or carbon, how can he knows that he can polish or wetsand the car safely ? Without any risk for the paint/clearcoat ?





  • How is possible to find 0,2 MILS on car ? 0.o


Thank you to take time to read my « big » message.


Friendly
 
Last edited:
There are special PTG's which will read on composite (fiberglass or carbon fiber).

That does seem odd that on your friend's car you measured 2.9 mils in the door jamb but only 0.3 mils on the body of the car. Is it possible you were measuring an aluminum panel and your PD8 didn't automatically switch to non-ferrous mode?
 
I'm wrong, I wanted to put 1.9 mils not 2.9, sorry for that error.
I checked if the PD8 was switching between Fe or nFe mod and it was. Couple minutes after I took measure on another car and I had results which seems correct.. Do you think that the problem can come from my PD8? Even if it seems to work ?
 
Well, something seems amiss as your total film build on the body of the car should be something like 4-6 mils, if you only have .3 or even 1.9 you'd be down in the primer.

What do you get with your PD8 on other cars? Perhaps it needs to be calibrated.
 
Ok, tomorrow I'll take another mesures on differents cars and I'll tell you. First, I'll try to reset the pd8 it cannot be bad. Thank you for all of your answers !
 
I have a question for you setec..

You told me that if I have 1,9 I am in the primer. But how is that possible, I read on mike's Phillips book and Meguiar's pro detailer told me that OEM factory clear coats have between 1.5 to 2.0 mils ( it depend about brand etc ) and I found 1,9 Mils..

Can you tell me where I'm wrong because I'm lost.
 
E-coat, primer, and color layer will typically measure between only 30-40 microns. Clear coat can range from 70-140+ microns depending on the manufacturer. Plastic bumpers seem to have different film build thickness compared to metal substrates.
 
WilliamG said:
I have a question for you setec..

You told me that if I have 1,9 I am in the primer. But how is that possible, I read on mike's Phillips book and Meguiar's pro detailer told me that OEM factory clear coats have between 1.5 to 2.0 mils ( it depend about brand etc ) and I found 1,9 Mils..

Can you tell me where I'm wrong because I'm lost.
Click to expand...

That's 1.5 to 2 mils of clearcoat. The metal has ecoat, primer, and basecoat on it before the clear.
 
I listened to your advice and I recalibrated my PTG.
I realized that the values he gave me was often varied.

So I think you were right setec, the problem is with my ug.

But I have one last question, I read that for e-coat - primer - base coat = approx 50/60 microns? What do you think or know about that?

Nicholas said it was 30/40?

I can not seem to find an item that can concretely give me an idea of values:

For example, e-coat 10/20 micron / primer 20/28 etc.

I understand more things now, and the problem is that i don't want to work or make more correction on a car without beeing sure of the thickness on a car. Are you using a different PTG ?


Anyway once again thank you to you for your help.
 
Every car is different so it's hard to give general answers. I have a Positector that reads individual paint layers. Film build of ecoat, primer, base coat is typically very thin. Less than 50 microns.
 
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