The Value of Paint Gauges

[shane@detailedreflections]

I know we talk a lot about paint correction and things of that nature.  What isn't discussed as frequently is how to know when you're safe to correct and when you're not, or how aggressive you can be in doing so.  For those purposes, a paint thickness gauge is invaluable.  There's a number of gauges out there that range in price from a little over $100 to thousands of dollars.  The one we use is a mid level gauge.  Before we take a polisher to any vehicle, we want to determine how aggressive we can be and if it will stand up to polishing.

The way we commonly do this is to measure the paint in multiple areas.  We then measure an area that won't have as thick of a clear coat on it (door jambs are a good one) and subtract it to get a feel for roughly what thickness of clear coat we are working with.  We can also discover quickly if a vehicle has had any paint work done on it.  Body shops will commonly lay down a much thicker clear coat than the factory.  

 

Here you can see a paint reading of 100 microns on an Infiniti G35 we recently did some work on.  This is a pretty common reading among paint that hasn't been touched.

In taking more readings, we came across a few panels that had much thicker readings.

This let us identity that those panels had been repainted.  While working with this vehicle, we found an isolated deep scratch that we wanted to pull out.

We took a quick reading and found the paint was VERY thick in this area thanks to the repaint.

Yup, 297 microns.  That's some thick paint to work with.  We went to work with some compound (that wasn't Adam's as we wanted a super quick cut and had something more aggressive on the shelf).  We followed it up with some correcting polish and finally a finishing polish.

In that photo, there was plenty more to be done on the vehicle, we were just working that one isolated spot.  A quick final reading shows we actually removed a significant amount of clear coat to remove the defect.

Through the use of a paint thickness gauge, we were able to determine how aggressive we could (or couldn't be) and could work confidently while choosing a product that would offer fast results.  Every vehicle has a story to tell.  And before we write our chapter on it with polishes, correction and general awesomeness in detailing we should take a moment to understand what's really going on.  On a vehicle with a much thinner coat of clear, I don't know as though we would have been quite so aggressive.  

Paint thickness gauges are an invaluable tool for anyone who's doing paint correction on a regular basis or where you're working on vehicles you don't really know the history of.

Just thought I'd share an experience with an area of detailing that is often not talked about much here.  

Enjoy and have a great weekend.

[Nickfire20]

Ive always thought about buying a meter but never did.

 

thanks for the info and the write up ?

[mc2hill]

6 hours ago, shane@detailedreflections said:

 

The way we commonly do this is to measure the paint in multiple areas.  We then measure an area that won't have as thick of a clear coat on it (door jambs are a good one) and subtract it to get a feel for roughly what thickness of clear coat we are working with.  We can also discover quickly if a vehicle has had any paint work done on it.  Body shops will commonly lay down a much thicker clear coat than the factory.  

 

Paint thickness gauges are an invaluable tool for anyone who's doing paint correction on a regular basis or where you're working on vehicles you don't really know the history of.

 

Thanks for the info Shane!  How many areas to you usually take readings on?  I recently purchased a Sunray/Eray coating thickness gauge and am working to standardize my process.

[shane@detailedreflections]

8 hours ago, mc2hill said:

Thanks for the info Shane!  How many areas to you usually take readings on?  I recently purchased a Sunray/Eray coating thickness gauge and am working to standardize my process.

I usually try to take a few readings on each panel. Ideally you should take them in the same spot each time for comparison, but it’s difficult to mark and then polish and have the same landmarks. There will be some deviation in readings due to differences in location or just the error of the machine.  All of that being said, if I find a reading that doesn’t seem right I’ll start to probe deeper and take more readings figuring it out.

I’ve been debating the idea of making a form to outline each panel indicating before polish, after polish and the finished product. That way the customer knows, and I have a record of it as well. 

I had the same or similar reader (it looks like a CEM which is rebranded frequently). It worked well. It has a larger margin of error than some of the DeFelsko units, but it’s also less than 1/4 of the price. I ended up getting the DeFelsko when the sensor probe went on my old unit.

Hope this info helps. If you have more questions, don’t hesitate to ask.

 

[ZMAN024]

Hi Shane, I have a quick question for you.  How can you tell how much of the thickness measurement is actually clear coat vs. paint ?  I've seen pics where others have "burned through" the clear coat down to the actual paint layer and ruined their day.  So, I understand taking measurements of areas with typically less clear like the door jams, and comparing against areas to be corrected.  In your example above, though, where the panel was repainted and you had a reading of 297 microns, how can you tell what portion of the thickness reading is clear coat ?  Is there a simple way or is it still a gamble ?

[shane@detailedreflections]

20 minutes ago, ZMAN024 said:

Hi Shane, I have a quick question for you.  How can you tell how much of the thickness measurement is actually clear coat vs. paint ?  I've seen pics where others have "burned through" the clear coat down to the actual paint layer and ruined their day.  So, I understand taking measurements of areas with typically less clear like the door jams, and comparing against areas to be corrected.  In your example above, though, where the panel was repainted and you had a reading of 297 microns, how can you tell what portion of the thickness reading is clear coat ?  Is there a simple way or is it still a gamble ?

That aspect is generally a gamble. There is a meter that will differentiate layers, but it runs close to $2250-2500.  The bigger benefit is that it will read even on composites.  It’s still more than I was willing to spend and more than most want to spend. My general thought is that a body shop will spray a thicker base AND a thicker clear. 

There is always some risk in removing material on any job. A gauge just gives you a stronger idea of what you’re working with. 

[Dan@Adams]

Strong write-up Shane! Thanks for the share

[mc2hill]

14 hours ago, shane@detailedreflections said:

I usually try to take a few readings on each panel. Ideally you should take them in the same spot each time for comparison, but it’s difficult to mark and then polish and have the same landmarks. There will be some deviation in readings due to differences in location or just the error of the machine.  All of that being said, if I find a reading that doesn’t seem right I’ll start to probe deeper and take more readings figuring it out.

I’ve been debating the idea of making a form to outline each panel indicating before polish, after polish and the finished product. That way the customer knows, and I have a record of it as well. 

I had the same or similar reader (it looks like a CEM which is rebranded frequently). It worked well. It has a larger margin of error than some of the DeFelsko units, but it’s also less than 1/4 of the price. I ended up getting the DeFelsko when the sensor probe went on my old unit.

Hope this info helps. If you have more questions, don’t hesitate to ask.

 

Here is the form I am currently using.  I have been using the same 8-10 areas to read, then do more if something looks odd.  This is from a BMW I have polished 2 times (overspray removal from a painting a water tower by work, and follow up after the first gen LED lights did not show up the marring as good as the sun).

 

[BG SQ5]

Great info!  

I'm curious how well these work on edges and sharper corners, as I assume those are the thinnest spots on a car that has had any point correction.

[shane@detailedreflections]

My gauge has a rounded probe and will do continuous reading. That being said, I don’t use it by dragging it across the surface for obvious reasons. My rule is that if the clear is thin, the edges are thinner. Usually you’ll see other signs of improper technique that would make you concerned about an edge being too thin coupled with the thin readings. 

[mc2hill]

On 11/12/2017 at 6:46 AM, shane@detailedreflections said:

I usually try to take a few readings on each panel. Ideally you should take them in the same spot each time for comparison, but it’s difficult to mark and then polish and have the same landmarks. There will be some deviation in readings due to differences in location or just the error of the machine.  All of that being said, if I find a reading that doesn’t seem right I’ll start to probe deeper and take more readings figuring it out.

I’ve been debating the idea of making a form to outline each panel indicating before polish, after polish and the finished product. That way the customer knows, and I have a record of it as well. 

 

Just a follow-up to this. 

I was doing pre-show wash and wax on a clients 1912 race car and wanted to play with my paint gauge.  This car is single stage, but he told me it has lots of paint on it.  I have corrected the hood 2-3 times before big shows, but was curious how much paint was left to work with.  The first reading was 732!!!!  Holy crap, "is this hood aluminum?" I asked, knowing I have gotten odd readings with my cheap gauge on a aluminum hood.  "Nope, all steel" was the reply.  I guess I can do a few more corrections, when needed! 

 

I measured several spots on the hood and cowl, and all were over 700!

[LSX Maestro]

Well I guess you can say he wasn't kidding about there being lots of paint!