Introduction to paint thickness gauges

Let's talk a little about paint thickness gauges today. You need to know a few things before buying a paint thickness gauge.

What are the 3 measurement principles of
paint thickness gauges?

The best tools for measuring paint thickness over external car materials are handheld electronic equipment. There are three varieties available, and the choice is based on the part's size and form, the type of coating, and the material being painted. These devices measure using magnetic, eddy current, or ultrasonic methods.

Magnetic Principle for Steel

Steel is magnetic, hence magnetic (ferrous) gauges that use mechanical or electrical processes are used to measure the paint thickness over steel.

The components of a mechanical gauge are a graduated scale, a calibrated spring, and a permanent magnet. A measurement of thickness can be made by measuring the force needed to remove the magnet from the coated surface. Low-cost magnetic pull-off gauges offer coarse measurements that are helpful in identifying fillers under the paint, such as bondo. Detailers seldom ever use them. Usually, accuracy is within ±5%.

Eddy Current Principle for Aluminum

Utilizing an eddy current approach, paint thickness is measured over all other metals, including aluminum. A coil inside the instrument's probe creates an alternating magnetic field that causes eddy currents to form on the surface of metals when the probe is brought close to a conductive metal surface. A second coil next to it can detect the opposing electromagnetic field produced by these eddy currents.

Eddy current coating thickness gauges, which are non-ferrous, function and appear similarly to electronic magnetic gauges. In addition, they make use of a constant pressure probe and show the results on an LCD with the ability to print previously stored measurement data.

In this industry, instruments that solely use the eddy current principle are comparatively rare. Gages that combine the principles of eddy current and magnetic fields into a single device are more common. Some make measuring easier by automatically converting, based on the substrate, between different operating principles. Usually, these "combo" units cost between $400 and $1,500.

Ultrasonic Principle for Plastic

When determining paint thickness on non-metal substrates like fiberglass and plastic, an ultrasonic approach is employed. An ultrasonic transducer built into the instrument probe pulses through the coating. In order to ascertain the coating thickness, the high frequency electrical signal that is produced when the pulse bounces back from the substrate to the transducer is examined. Certain layers within a multilayer system can be measured in certain situations. The price range is from $1,800 to $4,000.

How to estimate the thickness of paint?

The surface of your car needs to be touched with a PTG in order to accurately assess the paint thickness. To acquire precise and trustworthy results, you need to follow a few simple steps.

1. Clean the surface of your car.

Cleaning the region you wish to measure is strongly advised, but washing the entire car is not necessary.

Ensure that there are no obstructions that could affect a PTG's readings, such as loose paint, corrosion, dirt, or dust. For the most part, a clean towel will do the trick; no additional cleaning solutions are required.

2. Adjust the gadget's calibration.

While it's not required to calibrate your paint thickness gauge before each usage, it's crucial to do so on a frequent basis or anytime the measuring environment changes in order to guarantee the maximum level of measurement accuracy.

Checking the manufacturer's instructions and following the on-screen directions is the simplest way to accomplish the task. Usually, "calibration kits" are part of the packaging and contain different metal parts to represent different substrates.

3. Set the gauge in place.

Set the unit of measurement (if necessary), turn on the device, and position the probe on the surface you wish to measure. Make sure the gauge is making a strong touch with the surface; if needed, lightly press down on it.

4. Determine the paint's thickness

To begin the measurement, press one of the gauge's triggers or the measurement button. Hold the PTG firmly in place, and don't take it off until the screen displays the readings.

5. Examine and evaluate the outcomes

You will soon be able to view the outcomes of your measurements.

For the best accuracy, it is advised to take many measures at various surface areas, preferably at representative locations of the car (e.g., roof, trunk, doors, depending on the objective of the measurement).

This will assist you in deciphering the readings and comprehending the distribution of paint thickness on the exterior of your car.

What paint depth outcomes are good?

While the exact value that characterizes "good" paint depth outcomes is unknown, the majority of factory paint jobs typically fall between 100 and 180 microns (µm), or 4 and 7 mills, on average.

It's customary to think about these rules:

• European cars – 100-150 microns (4-6 mills)

• American cars (USA) – 100-150 microns (4-6 mills)

• Japanese cars – 90-120 microns (3.5-4.7 mills)

How much paint should be applied to a car?

The manufacturer, measuring location, and color all affect the paint thickness of cars; it is not a constant number. The typical original car paint thickness is between 90 and 150 μm; Japanese cars typically have paint thicknesses between 95 and 105 μm, which means their paint is relatively thin; German cars typically have paint thicknesses between 110 and 130 μm; American cars have paint thicknesses between 120 and 150 μm, which means their paint is thick.

The paint thickness on the roof of the same car is often thinner here than it is elsewhere. Additionally, the door panels' paint thickness is marginally thicker than in other places. In general, there should be no more than 20 μm of variation in paint thickness across places. It is advised that users utilize paint thickness testers to take many measurements before summarizing their experience if they wish to know the precise paint thickness at different areas on an automobile.

How can I assess the used car's value with
the paint thickness tester?

The paint thickness following sheet metal work and repainting the vehicle will be more than before. The location of the repainting can be easily determined if the paint thickness is highly uneven, which can be determined by using the paint thickness tester to measure the same spot multiple times. If the paint thickness is more uniform, you will need to measure the paint thickness at other locations or compare it to the original paint thickness. Next, determine if this area has been painted over.

You can also test the paint thickness at several different points on the roof and average the results if you are unsure of the original car paint thickness's approximate range. This is so because there are seldom any impacts or other types of damage to the automobile roof. Most second hand cars still have their original paint on the tops. Measure the paint thickness in various spots based on the roof's paint thickness.

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