Magnetic paint thickness gauge

T

twheat

New member
I have decided I want a paint thickness gauge. To me for a person who details just their own cars I don't need a digital like the pros use. I think a magnetic paint thickness gauge would be fine for me. Mainly I want to use it on my 91 BMW M5 with single stage paint. While I have never compounded the car in the 11 years I have owned it I want to make sure it has a thick enough layer before I hit it up with some Power Gloss to get rid of the oxidation. So thats really why I just want a reasonably priced magnetic paint thickness gauge. So what are you guys using? Thanks for the help!
 
I have a Mar-Hyde Gauge, just like the above one. Got it for $15.00 from my local PBE store.

Search for Mar-Hyde #1099.
 
Accurate enough for what you need it for. Accurate enough for my use too.

As accurate as a $1400.00 super digital, print-out, computer accessible one? No.

Accurate enough? Yes.
 
I have a pen gauge and i rarely use it. Not accurate enough, really. I basically

check for prior repairs and nothing else. Can't recommend it for anything else.

Check paint thickness? Forget it. It's NOT the same difference between a digital

and analog caliper.
 
I understand that they aren't as accurate all the electronic gauges, but for me as a weekend warrior who only details his own vehicles I feel I don't need an expensive gauge. I will really only be using it to get the thickness of the paint on my 91 BMW M5 that has single stage paint before I use power gloss on it. I want to make sure it is not too thin for compounding? Can the pen gauges really be that inaccurate?
 
Can the pen gauges really be that inaccurate?
Click to expand...



Yes. I'm guessing +/- 10% or more... There's a magnet and a calibrated

spring inside that wears out (less accurate). I don't have a digital gauge

to check, however... You must be needing serious correction? Can you post

some pics??



There are several in-depth threads regarding gauges and accuracy.
 
There are just some spots on the car that need to be compounded. Definitely not the whole car. I just want to extra cautious though. I have never compounded the car in the 9 years I have owned it, but I am not sure about the previous owner.
 
On the Mar-Hyde there is a calibration to make up for the loss off tension in the spring over the years. There's different scales on it for measuring horizontal panels, vertical, and upside down. It's accurate enough for your use. Measure before and after you compound/polish.

But you need to practice with it first to get the hang of it.
 
The Pro Gauge II claims 0.001 accuracy or better:



Gardco :: Pro Gauge II



Automotive Paint Detailing: Paint Thickness Meters, Gauges



More good read:



Automotive Paint Detailing: Paint Thickness Meters, Gauges



Excerpt from above:



"Because of the potential for removing the majority of the UV blockers, most auto manufacturers recommend that a maximum of 0.3 mils (8 microns) clear coat be removed as prevention from UV damage to underlying paint layers. In a worst-case scenario with a single stage paint process, buffing down to the primer may result in a costly trip to the paint booth."



Can you accurately measure 0.3 mils with a pen type gauge?
 
Cool thanks for the links. That is a good link to read. Anyways I called my buddy today who owns a body shop and he is gonna bring his paint thickness gauge over one night after work to get some numbers. He said it is one of the digital ones that cost a bunch of money so that should work good. On single stage paint what is a good thickness that would be safe to compound areas that are oxidized?
 
Flashtime said:
The Pro Gauge II claims 0.001 accuracy or better:

>>>>SKIP>>>>

Excerpt from above:



"Because of the potential for removing the majority of the UV blockers, most auto manufacturers recommend that a maximum of 0.3 mils (8 microns) clear coat be removed as prevention from UV damage to underlying paint layers. In a worst-case scenario with a single stage paint process, buffing down to the primer may result in a costly trip to the paint booth."



Can you accurately measure 0.3 mils with a pen type gauge?
Click to expand...



Certainly not. Did you read the original post?
 
Yeah I read it definitely but, I have also read in one of David B's posts that from 6 to 8 mils is safe. The difference between 3 mils and 6 to 8 is a lot thats all. Here is a quote out of David B's guide to polishing.



"If paint thickness is less than 6 to 8 mil, it's not safe to wet-sand or compound. If paint thickness is less than 4 or 5 mil, it is not safe to polish with a material higher than grade 2 on the polish chart."



I guess I am confused on what the minimum should be. I will do some searching to see what I can find. Thanks for the help.
 
OK so what I found says the minimum thickness should be 3 mils so anything in the 4 to 5 range is good to go.
 
Heatgain, the question was rhetorical. In a nutshell, if the compounding/polishing

removes enough to tell with a pen gauge, then that's quite a lot... It's a bit tricky

to hold it steady as is. I have the Mar-hyde unit as well.



On single stage paint what is a good thickness that would be safe to compound areas that are oxidized?
Click to expand...



Is the paint original? Your body shop pal will be able to tell you. From what other pros

tell me (body/paint pros), sanding and compounding/polishing can remove about a mil.

It would be impossible to measure 0.3 mils as recommended without an accurate gauge.

Start with the least aggressive approach (naturally). And after you're satisfied with

your results, follow up with good sealant/wax. Then maintain it! :)



BTW, i own small body shop and do all the paint and "detail" work...
 
twheat- I've never seen a magnetic gauge that was good enough for anything other than spotting repaired areas. Considering that a few microns/fractions-of-a-mil is one *very* fine measurement, and *especially* considering that your paint is only original once, IMO anything less than a digital/electronic gauge is false economy.



The cost of a digital gauge is less than the cost of having some paintwork done.



Hey, I'm not a pro, and I hardly *ever* correct the paint on my vehicles, but I bought a decent gauge just to diminish the chances of an "OOPS!". Now if I'd only bought one that was a bit more user-friendly :o
 
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