How to use a Paint Thickness Gauge (PTG)

[hernandez.art13]

Hello everybody, I left the title really general in case others searched and needed information in the long run. I got a quick run through, through my estimator uncle on how to use a PTG. He was pretty impressed with the one I have opposed to the one he uses.

He said they call the readings Mils at the shop he works at.

19817
19810
^Repainted Hood
19811
^Blended Fender
19812
^Side View Mirror
19813
19814
^Roof
19815
^trunk
19816
^Spoiler

Extremely neglected Rx7
19818
19819
^Fender
19820
^Hood
19821
^Trunk

I am still learning and this thread is to further educate me and others on how to use a paint thickness gauge.

Thank You,
Art

[hernandez.art13]

Does it matter if a car is extremely dirty or have multiple layers of wax to get an accurate reading?

[Setec Astronomy]

A "mil" is the term used in the films (including paint film) industry, and it's .001 or one-thousandth of an inch. You use this in referring to paint or coating thickness as well as films such as plastic bags, etc.

Multiple layers of wax aren't going to be thick enough to make any difference with the accuracy of your instrument, it would be a good idea to get any dirt off as that may have significant thickness or particulate and could hold the head off the surface.

You can see the repainted panels in your measurements, the ones with 10+ mils, vs. the 4-5 mils of the factory panels.

[Evan.J]

Search feature helps :


What you're looking for when you measure the thickness of the paint on your car is uniform measurements. That is, measurements all withing a close range of one another from panel to panel and if you're lucky, over the entire car.

If you see a big change between readings on a single panel this would be a sign of potential risk or problems especially if you find thin paint surrounded by the norm readings. You should also look for signs of previous buffing work on panels with thinner paint, like lack of orange peel in the thin area but the orange peel kicks back in around the normal readings.

If you find thicker paint measurements around the normal readings this could be a sign of underlying bodywork from a repair.


There's a number of good reasons to use a Paint Thickness Gauge, I think I outline them in the second edition of my how-to book.

If I'm going to buff out a car, the primary reason I use a paint thickness gage is to help me make what I call, the "Go" or "No Go" decision. That is as a "Big Picture Indicator" as to where the paint is safe to work on or if there are areas to either avoid or tread lightly.

I was really glad I measured the paint thickness on Wayne's classic Hudson Hornet as it helped me to choose the path of using the least aggressive products to get the job done and the results still turned out great and there were no polishing related problems.

Wayne Carini 1954 Hudson Hornet Original Paint Restored by Mike Phillips (http://www.autogeekonline.net/forum/ask-expert-featuring-mike-phillips/63665-wayne-carini-1954-hudson-hornet-original-paint-restored-mike-phillips.html)


This is thin paint...

http://www.autogeekonline.net/gallery/data/1844/Thin_Hudson_Paint_002.jpg




:xyxthumbs:

[hernandez.art13]

I wonder why this was giving me a reading of 19822

Then it have me this reading where it was just rust.

19823?

[Setec Astronomy]

Because you were reading the thickness of the rust.

[hernandez.art13]

A "mil" is the term used in the films (including paint film) industry, and it's .001 or one-thousandth of an inch. You use this in referring to paint or coating thickness as well as films such as plastic bags, etc.

Multiple layers of wax aren't going to be thick enough to make any difference with the accuracy of your instrument, it would be a good idea to get any dirt off as that may have significant thickness or particulate and could hold the head off the surface.

You can see the repainted panels in your measurements, the ones with 10+ mils, vs. the 4-5 mils of the factory panels.

Thank You, I will give this area a nice wipe to see if there is a significant difference when I get home

19824

[hernandez.art13]

Makes sense... Now someone else could learn something...

Like this? Woops... Lol

http://www.autogeekonline.net/forum/showthread.php?t=64727

[erichaley]

I was using my PTG today on the AMX Mike Phillips and others wet sanded cut and buffed (see Helping in the Heartland), and I was getting readings from 23 mils all the way up to 44 mils!!

[Setec Astronomy]

I was using my PTG today on the AMX Mike Phillips and others wet sanded cut and buffed (see Helping in the Heartland), and I was getting readings from 23 mils all the way up to 44 mils!!

I guess that's another story what you were doing working on that car, but apparently that guy sprayed a lot of clear.

[hernandez.art13]

Was doing reading and saw ZmcGovern's work on the BMW, what an awesome job he did.

Found no rust, dirt or wax prior to using the PTG btw.

[erichaley]

If I told you...

I was actually there doing some paint correction on Wes' 99 BMW 528i wagon. To say the paint is rough is an understatement. Severely scratched, pitted, you name it. Did a test spot and, for as bad as it was, it turned out pretty damn nice!

You can see just how rough it was:
https://photos-6.dropbox.com/t/0/AACsovULBwMBOVBXYtzRM0lViO_uHrYA4h0NSZ_ssO5rKQ/12/2218087/jpeg/1024x768/3/1374033600/0/2/Photo%20Jul%2016%2C%206%2018%2001%20PM.jpg/OxXxzqFBefDIW3C9rpgiZgbvdHFXLWBIa8PeSTyhlfc

And how it turned out:
https://photos-4.dropbox.com/t/0/AADFzhpI0wd_n2wdjLncvAUeKXmRtMGT6yvsHGJT2KLSAg/12/2218087/jpeg/1024x768/3/1374033600/0/2/Photo%20Jul%2016%2C%207%2002%2039%20PM.jpg/tD35_TQJ5YDmU46d66j-tRv45986x6PXK9qlZDnn4xY

https://photos-3.dropbox.com/t/0/AABAD2enf3iU0k3ChdM7QmjbwMt4IGqrdDvEu5hrwu4qhw/12/2218087/jpeg/1024x768/3/1374033600/0/2/Photo%20Jul%2016%2C%207%2006%2028%20PM.jpg/vtCe1E7Su3AwgjeIjFQsWZ23T8_D-x5_SJe1QPgvScI

[hernandez.art13]

So 120-150 is healthy paint? What happens if it goes below that?

The lowest I got on my car was the roof, where it read 100

And does anyone know at what no. CC failure happens? Or is a case by case basis?

[hernandez.art13]

If I told you...

I was actually there doing some paint correction on Wes' 99 BMW 528i wagon. To say the paint is rough is an understatement. Severely scratched, pitted, you name it. Did a test spot and, for as bad as it was, it turned out pretty damn nice!

You can see just how rough it was:
https://photos-6.dropbox.com/t/0/AACsovULBwMBOVBXYtzRM0lViO_uHrYA4h0NSZ_ssO5rKQ/12/2218087/jpeg/1024x768/3/1374033600/0/2/Photo%20Jul%2016%2C%206%2018%2001%20PM.jpg/OxXxzqFBefDIW3C9rpgiZgbvdHFXLWBIa8PeSTyhlfc

And how it turned out:
https://photos-4.dropbox.com/t/0/AADFzhpI0wd_n2wdjLncvAUeKXmRtMGT6yvsHGJT2KLSAg/12/2218087/jpeg/1024x768/3/1374033600/0/2/Photo%20Jul%2016%2C%207%2002%2039%20PM.jpg/tD35_TQJ5YDmU46d66j-tRv45986x6PXK9qlZDnn4xY

https://photos-3.dropbox.com/t/0/AABAD2enf3iU0k3ChdM7QmjbwMt4IGqrdDvEu5hrwu4qhw/12/2218087/jpeg/1024x768/3/1374033600/0/2/Photo%20Jul%2016%2C%207%2006%2028%20PM.jpg/vtCe1E7Su3AwgjeIjFQsWZ23T8_D-x5_SJe1QPgvScI

^Mirror finish! Great job!

[erichaley]

So 120-150 is healthy paint? What happens if it goes below that?

The lowest I got on my car was the roof, where it read 100

And does anyone know at what no. CC failure happens? Or is a case by case basis?

On my 2013 Honda Accord, I've found 100 mils to be about the lowest I am comfortable going. Signs of impending strike through occur at around 80, with full strike through not far behind. I'd say, in my case, that below 100 is seriously dangerous territory. One can't be willing to do serious paint correction on someone else's car unless they know what failure looks like on their own.

I'm comfortable in my mistakes as I've learned a great deal about what it takes to fix it and, more importantly, how to avoid it in the future.

I repainted part of this door and recleared the entire thing:

https://photos-6.dropbox.com/t/0/AAAFYIBgBJUFUDoe1fHMsfhA8sh0x_mTIWhjf_3KKk9-Zg/12/2218087/jpeg/1024x768/3/1374033600/0/2/July_16__2013_at_0415PM.jpg/t-0r7HNvUvj9P_nF2JMb-tBh3bEyUk400xZkrGvepCI%2CpUXKRTBR7JsSkTDucZ9eVx11P 4YdApPQeBZJauDN5SU

Using aerosol cans...