Paint thickness gauge

[MNDSMtuner96]

Just got a paint thickness gauge and am new to measuring paint. The one I have is just a cheaper one that measures all three layers. Just wondering, what's your rule of thumb when it comes to measuring paint thickness? How do you know if you can or can't wet sand/compound? Any advice is much appreciated!

[Rsurfer]

Just got a paint thickness gauge and am new to measuring paint. The one I have is just a cheaper one that measures all three layers. Just wondering, what's your rule of thumb when it comes to measuring paint thickness? How do you know if you can or can't wet sand/compound? Any advice is much appreciated!

I have wet sanded a new trunk on a Nissan that I thought was safe to wet sand (120 microns) and burned through using 2000 grit sand paper. Wet sanded may cars in the past, but it only takes one strike through to make you weary.

[builthatch]

it's impossible to know for sure. massive experience gives you an index in your head, so you end up knowing what years of what makes with what models made in what factories come with what sort of thickness...but other than that, it's so hard to know for sure.

some people say they use the door jambs as a guide for clear - the theory is that the jambs have the least amount of clear so you can loosely compare and contrast that measurement vs. your exterior panel to gauge.

i have a DFT Combo gauge and what i've found is that it's most useful to help quantify how much work you've done. you can go around on a given panel and get an idea of what the panel has...maybe compare it vs. similar panels on the car and get an idea of where it should be to start. plus that can help detect if your panel is particularly higher or lower vs. the others.

[FUNX650]

Note:
µ = microns

The following are some of the coating industries' current average
thickness-standards, that have been adopted at many OEM's paint kitchens.
______________________________________________

E-coat.............1.0-1.2 mils = 25.4µ--30.48µ
______________________________________________

Followed by:

•Primer Surfacer...~1.2 mils = ~30.48µ
•BaseCoat........0.4-1.0 mils = 10.16µ--25.4µ
•ClearCoat........1.4-2.2 mils = 35.56µ--55.88µ
_________________________________________
Total..................3.0-4.4 mils = 76.2µ---111.76µ

Add E-Coat.......1.0-1.2 mils = 25.4µ---30.48µ
__________________________________________
Total Thickness..4.0-5.6 mils = 101.6µ---142.24µ

Now:
In order to stay within OEMs' paint warranty recommendations:
•CC removal: no more than: 0.3-0.5mils = 7.62µ--12.7µ


So...Using the above #s:

If the starting EPTG measurement reads: 4.0 mils/101.6µ...
Then:
At the end of all of the sanding/compounding/polishing steps, (while the vehicle's paint is under warranty), the EPTG measurement should be no less than: 3.5mils = 88.9 µ

-IMHO...
When it comes to certain "paint correction" steps:
Extreme Caution should be exercised when EPTG readings are anywhere near the low end of the spectrum!!

YMMV.

Bob

[MNDSMtuner96]

Thanks guys. What's an "E" Coat?

[builthatch]

Thanks guys. What's an "E" Coat?

it's like powder coating but with paint. they charge the components so they are attracted to each other. they can help control a lot of aspects of the finish by manipulating the voltage.

[allenk4]

Bob,

Where are those numbers from?

I have not seen it stated so definitively before

Kyle

[FUNX650]

Bob,

Where are those numbers from?

I have not seen it stated so definitively before

Kyle
My friends over at BASF and DuPont!

Food for thought.
Talk about trouble determining total paint thickness:
How many EPTGs, that can measure 3 film layers, will become anachronistic...when all of the OEMs start incorporating the primer/color-coat?!?!


Bob

[MNDSMtuner96]

How many manufacturers use the E coat?

[builthatch]

My friends over at BASF and DuPont!

Food for thought.
Talk about trouble determining total paint thickness:
How many EPTGs, that can measure 3 film layers, will become anachronistic...when all of the OEMs start incorporating the primer/color-coat?!?!


Bob

i don't think that will change anything other than the standards for what we expect to see when we measure...until it becomes common knowledge that X automaker is doing that.

if a gauge can measure three individual layers, it will then show two in your scenario. if that combo happens (don't know anything about it), then hopefully they will have gauges that can read indiv layers on AL and steel panels in the first place lol

[Setec Astronomy]

How many manufacturers use the E coat?

Everybody E-coats, when you see those pictures of the car body on a rail going through those big dip tanks, that's the E-coat line. As builthatch said, the car and the paint are charged so the paint is electrically attracted to the metal, that makes sure it gets in all the nooks and crannies and weld areas, etc.

EDIT: Back to your original question, it's all a crap shoot, the PTG just gives you another data point to hang your hat on (or hang yourself with), as Rsurfer pointed out.

[Niblick]

As a rule of thumb anything under about 100um is starting to get down to the wire, but as the guys have already said, it varies from vehicle to vehicle. I've taken 3 stage paint down to 87um on my own vehicle in the past without going through. But it's damn close to CC failure at that point, and not something i would chance on a clients car.
the Pelt thickness gauge that i posted a link to recently claims to measure up to five layers, though presumably they are counting the panel itself in there as well. Even so, it should cope with cars with an E-coat as well as the three 'normal' coats.
The thing i like about a PGT is that you know if its too thin to risk sanding or machining before you start. i just don't work without one now, its not worth it. I've turned several jobs down on the back of measurements I've taken, and i sleep well lol

[allenk4]

Hi Kyle,

Thank you for your inquiry.

I would be happy to give you some more information about the PELT gauge. The cost of a PELT gauge with onsite training and calibrations is about $50,000.

Before I can formally quote you I need to know more information about your application.

Can you tell me a little more about your company and what your measurement needs are?

Best Regards,

Renée G. Basset



Download pictures

The leading multi-layer coating thickness gauges

[Rsurfer]

Hi Kyle,

Thank you for your inquiry.

I would be happy to give you some more information about the PELT gauge. The cost of a PELT gauge with onsite training and calibrations is about $50,000.

Before I can formally quote you I need to know more information about your application.

Can you tell me a little more about your company and what your measurement needs are?

Best Regards,

Renée G. Basset



Download pictures

The leading multi-layer coating thickness gauges
I'll take two, one for back-up.:xyxthumbs:

[Niblick]

well i did say they weren't cheap lol
at least we know the technology exists.