Paint thickness Q's

octane

octane

New member
Apr 9, 2012
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So I'm thinking of doing a compound on my car, already did a polish on it when I got it new last year.

from my ebay paint gauge I have from 4.8 mils to 6.0 mils of paint thickness (freshly calibrated)

are those numbers good? should I have lots of clear left to do a compound? or is that on the thin side?

this is for a black toyota rav4 (2012) with pretty soft paint.
 
Those numbers are considered to be good, healthy readings and not on the thin side. Those translate to roughly 120-150 microns which is considered to be "normal OEM thickness". Thin paint is typically < 100 microns.
 
zmcgovern45 said:
Those numbers are considered to be good, healthy readings and not on the thin side. Those translate to roughly 120-150 microns which is considered to be "normal OEM thickness". Thin paint is typically < 100 microns.
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Yep. Anytime I see anything under 100 it gets no more than a medium polish. Anything under 80 I dont do anything other than a finishing polish. But when you get into the 120 and above id say thats good healthy paint.
 
Thank guys! what a relief! so I guess mesuring in microns is easier!
 
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


This is thin paint...

Thin_Hudson_Paint_002.jpg





:xyxthumbs:
 
well up to now, all seems pretty uniform, the top and bottom of the doors are a bit thicker around 150microns, and the middle of the panels are more around 125microns.

I think I'm really starting to like this "paint gauge thingy" as my wife calls it...
 
That range is still very uniform... remember, 1 micron is equal to .001 mm while 1 mil equals .0254 mm... therefore reading in microns allows you to detect much smaller changes in thickness. You should be worried if most of your car averages ~130 microns and then you measure a panel that averages ~60 microns or ~300 microns.... those types of inconsistencies would typically mean something is not right.

My fiance's Mazda, however, uniformly measures very thin (around 70 microns) so I did not feel like anything was wrong... it just had thin OEM paint. Research confirmed that Mazda does in fact use a paint process that results in very thin coverage, so as Mike said... finding non-uniform readings is your major concern.


Don't rely solely on your PTG though to determine if an area has been repainted, carefully inspect each panel for visual inconsistencies as well. This Audi had clearly been repainted, although the PTG showed fairly uniform readings compared to the original panels. This led me to believe that the entire panel was replaced and repainted in stead of simply resprayed... but I am no body shop expert.

Notice the obvious difference in texture between the 2 panels.
947027_247365505401576_1607492915_n.jpg
 
zmcgovern45 said:
My fiance's Mazda, however, uniformly measures very thin (around 70 microns) so I did not feel like anything was wrong... it just had thin OEM paint. Research confirmed that Mazda does in fact use a paint process that results in very thin coverage.
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Wow 70 mics. for OEM paint. What year Mazda?
 
zmcgovern45 said:
That range is still very uniform... remember, 1 micron is equal to .001 mm while 1 mil equals .0254 mm... therefore reading in microns allows you to detect much smaller changes in thickness. You should be worried if most of your car averages ~130 microns and then you measure a panel that averages ~60 microns or ~300 microns.... those types of inconsistencies would typically mean something is not right.

My fiance's Mazda, however, uniformly measures very thin (around 70 microns) so I did not feel like anything was wrong... it just had thin OEM paint. Research confirmed that Mazda does in fact use a paint process that results in very thin coverage, so as Mike said... finding non-uniform readings is your major concern.


Don't rely solely on your PTG though to determine if an area has been repainted, carefully inspect each panel for visual inconsistencies as well. This Audi had clearly been repainted, although the PTG showed fairly uniform readings compared to the original panels. This led me to believe that the entire panel was replaced and repainted in stead of simply resprayed... but I am no body shop expert.

Notice the obvious difference in texture between the 2 panels.
947027_247365505401576_1607492915_n.jpg
Click to expand...

If I saw this, I automatically think to myself, "been repainted"

The PTG does't exactly measure CC (ONLY) does it? It measures paint and primer as well?
 
hernandez.art13 said:
If I saw this, I automatically think to myself, "been repainted"

The PTG does't exactly measure CC (ONLY) does it? It measures paint and primer as well?
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It depends on how much money you spend on your PTG. Chances are you would have a gauge that measures total film thickness... this would include any primer, base coat, and clear coat (if bc/cc paint system and not single stage, for example). These gauges help to aid you in making better decisions based on the information you are given, however they cannot tell you exactly how much clear coat you have to work with.

There are ultra-sonic gauges that can in fact measure the thickness of each layer of material on top of the metal, however these gauges will cost several thousands of dollars, which make them impractical to most hobbyists/weekend warriors.
 
octane said:
So I'm thinking of doing a compound on my car, already did a polish on it when I got it new last year.

from my ebay paint gauge I have from 4.8 mils to 6.0 mils of paint thickness (freshly calibrated)

are those numbers good? should I have lots of clear left to do a compound? or is that on the thin side?

this is for a black toyota rav4 (2012) with pretty soft paint.
Click to expand...

But compounding wouldn't do much besides take of more CC? But if a 3000 and 5000 were used. Wouldn't that let you hide/mask the CC finish so the orange peel is not as noticeable?
 
hernandez.art13 said:
But compounding wouldn't do much besides take of more CC? But if a 3000 and 5000 were used. Wouldn't that let you hide/mask the CC finish so the orange peel is not as noticeable?
Click to expand...

I'm not too sure what you are asking/saying...

Both compounding and sanding effectively remove clear coat, however sanding will remove more material at a faster rate therefore it is often used to level orange peel. You are not "hiding or masking the CC finish" simply removing enough of the texture to produce a completely flat surface. So in reality, if you wanted to make 100's of passes with a cutting pad and compound, you could probably produce the same results as sanding... however, this is obviously not efficient or logical.

Either way, this does not at all tie in to the OP's question, so we should keep this thread on topic
 
Mike, when taking readings on a panel with a PTG, how much distance should there be between each one (i.e. take a reading every x inches)?
 
Both of those pieces were metal panels... this inconsistent texture was found on the entire passenger side (both doors) which looked completely different than the doors on the driver's side.

erichaley said:
Mike, when taking readings on a panel with a PTG, how much distance should there be between each one (i.e. take a reading every x inches)?
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There is no right answer for this... take as many or as few readings as you feel comfortable with. Obviously the more the better. I tend to take one every 8-12" and note any major changes.
 
I have never used one, in the beginning Here on AG "I got questioned why wouldn't I use one?"

Still don't know what to say besides "I never got trained to use one"

If it is OEM CC then it can be sanded down. But one has to always tread lightly or not at all if they are unfamiliar with who and how it was painted. (Especially for CC sanding)

Don't remember who posted this but was very inspirational to me.

View attachment 18127
 
Rsurfer said:
With that much orange peel, you don't need a paint gauge.
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Not sure what you mean? This area measured approximately the same values as the OEM paint, so why would you not want to measure it first to see what you have?

hernandez.art13 said:
If it is OEM CC then it can be sanded down. But one has to always tread lightly or not at all if they are unfamiliar with who and how it was painted. (Especially for CC sanding)
Click to expand...

I don't necessarily agree with this... once again, I will refer to our 2010 Mazda SUV. The OEM paint readings average around 70-75 microns, this is simply something I would never touch with sandpaper unless I had a really really good reason to risk it.

OEM paint, in general, is usually much thinner than re-painted panels. Also, you can ask the painter to add a layer or two of clear coat if you are getting a panel resprayed, so you know you have more room to work with. For a DD vehicle, CC is very valuable, so I would much rather live with some orange peel than deal with CC failure down the road.
 
zmcgovern45 said:
Not sure what you mean? This area measured approximately the same values as the OEM paint, so why would you not want to measure it first to see what you have?

For a DD vehicle, CC is very valuable, so I would much rather live with some orange peel than deal with CC failure down the road.
Click to expand...

Perhaps what Rsurfer meant was that if the peel is that heavy, you can see when you level it while sanding. Which is fine if the peel is all in the clear and none of it is telegraphing from the base, and if the person sanding is careful and experienced enough to not sand any of the valleys.

When all is said and done with this project--the OP has said he's going to follow with a coating which should restore some of the UV protection, and it's the trunk lid which would be a lot easier to respray than if he was sanding the roof, if there is ever a problem.
 
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