Car paint thickness gauge and car paint layers

A paint thickness gauge (or paint depth gauge) is used to measure the thickness of a vehicle's paint layer to determine whether the car has received a new paint coating after leaving the factory (either due to a previous accident, paint damage, etc.) or not. ). The repainted body part gives a higher reading than the part wearing the original paint.

When using a paint thickness gauge, you'll find that no matter where you place the gauge, you'll always get a different reading - even on the same body part. The readings aren't as high or as low as you'd expect, so you can't tell if the body part has original paint or not.

Figure 1. Paint Thickness Gauge NE00317

• Your car does not have a factory paint thickness rating - factory readings can vary significantly between panels (body parts) (and even within the same panel).
• There is no universal number to stick to when comparing readings
• If you're looking for "something bigger" than a specific number, you're doing it wrong - especially if you think it applies to any car
• Why do some panels on older cars show significantly higher readings than the rest of the car
• Different colors and surface shapes generate different readings
• Why readings can vary drastically between different model years and manufacturers
• A repainted panel may not show as high a reading as you think

What to look for and how to read the meter reading?

Let's start with the basics. You have to understand that cars are painted homogeneously at the factory. Because the entire body is e-coated and electrocoated (Sometimes called electrocoating, electrophoretic coating, or electrocoating, e-coating is a high-tech process in which metal parts are coated with a protective finish by immersing them in a chemical bath and applying an electric current.) , the factory paint thickness is pretty much everywhere. uniform. High-tech paint applicators combined with intensive quality control mean that there is little variation in panel paint thickness. So, assuming the entire car hasn't been repainted, you're looking for consistency across all metal panels on the car. If the driver's door reads 110 microns and the adjacent fender reads 220 microns, you can pretty much bet the fender has seen paint. A repainted panel will always have a higher reading than the original color, but as you take continuous measurements, you'll encounter a dizzying array of numbers. Exactly how much higher does it read? How to distinguish the reading of the factory color from a repaint?

Paint thickness is mostly referred to in microns (μm).

Figure 2 shows the layers of the factory painting process and their thickness in microns.

Figure 2


The reality is that overpainted panel thickness can vary astronomically. There is no "magic number" where the factory color reading stops and the spray starts as every manufacturer is different.

In reality, the majority of repainted panels measured are 200 microns or more. Some can be as ridiculous as 350 or 400 and some can read as low as 148 microns. Having done thousands of readings, I can tell you from experience that a difference of 40 microns or more between adjacent panels (measured on comparable surfaces) is a red flag, especially on modern cars. This prompts further investigation to find evidence of paint coating. Many variables affect paint thickness.
 

Why do repainted panels count higher than factory colors?

The paint thickness of the repainted panel is always greater than the paint used in the factory. Electromagnetic bell sprayers apply charged paint to the oppositely charged auto body, resulting in a 90%+ transfer rate (most average body shop HVLP guns have a 40% transfer rate). This high transfer rate means less paint is used per coat, and with a charged surface that magnetically attracts paint, a single application of base coat is enough to ensure even coverage across the panel while achieving excellent depth and gloss. In comparison, body shops need 2-3 base coats to achieve the same coverage and gloss.



Figure 3. Paint Thickness Gauge MPBTP13SAL


The factory's paint shops also use techniques such as primer and clear tinting to complement the color of the base paint, which further reduces the amount of paint needed to cover the panel. Less paint equals less cost for the manufacturer, and the paint department applies such even coverage that the film is less than 100 microns thick, but still looks brilliant.

This is not an insult to the finishing industry - they do a fantastic job considering what they have to work with. They're not as concerned with getting the thinnest possible coat - the ultimate goal is to bring the quality of the repair up to par with the rest of the factory paint job, and that requires multiple coats. The result is a paint finish that looks equal to or better than the factory paint.

Here you can find all the car paint thickness gauges available in our online store.