ERAY P1 Coating Thickness Gauge Review

Paint thickness gauges are handy tools to have on hand. Whether you are a car detailer or just somebody who wants one to measure the thickness of a particular vehicle’s paintjob prior to purchasing it, these tools have all sorts of use cases.

In this review we are going to be looking at the ERAY P1 coating thickness gauge and whether or not we think it is a good buy.

Why Do We Need to Measure the Thickness of Paint and Clearcoats?

Being able to quickly and accurately measure the thickness of a vehicle’s paintwork and clearcoat (or any other item for that matter) is important when it comes to repainting, buffing and polishing. For example, if the clearcoat is too thin and/or too much is removed, it can lead to issues such as premature fading and delamination. Additionally, buffing and polishing on thin coatings can lead to paint damage if you are not careful, so knowing the thickness of the clearcoat/paint is very important.

Another reason why you might want to measure the thickness of a vehicle’s finish is when you conduct a used car inspection. Bodywork problems can be a nightmare to fix and can severely impact the value of a used car. Having a paint thickness gauge on hand can be a really useful tool to work out whether or not the vehicle you are looking at has had some sort of repair work in the past.

For example, if you find that the thickness of the car’s finish is much higher around one of the wheel arches than on the other ones it could suggest that the vehicle has had some work done. While the gauge won’t tell you what happened prior to the respray, it does let you know that an issue may have occurred. This problem could have been anything from rust, accident damage or something relatively minor like stone chip damage. You can then ask the seller of the vehicle about this to gauge their reaction and try to get a discount.

How Much Does the ERAY P1 Coating Thickness Gauge Cost?

The ERAY P1 is available in two colours, green and grey, from Amazon for US$109. If you would prefer to buy directly from ERAY themselves, you can find the P1 for sale here at a slightly higher price of $119 (obviously these are the prices at the time of writing and they may change).

The $100 price point is around the midpoint for these digital consumer coating thickness gauges, with other options coming in at anywhere from $20 to upwards $300 for higher end models (more professional gauges can be far more expensive than this).

Who is ERAY?

Before we get into the P1 thickness gauge itself, we thought we would take a moment to look at the company behind the gauge. There seem to be more and more scam companies out there these days and with the explosion in fake reviews, it can be hard to determine whether or not an organisation or company is legitimate.

ERAY was founded in 2013 in Shenzhen, China, so the company has been around for a while now. We also know this ourselves as we have seen their products being sold for a number of years now, so its not like they were just setup yesterday. ERAY’s products also generally have good feedback and reviews on multiple sites and from loads of different individuals.

We also haven’t heard of too many issues with their customer service apart from the fact that they often refer buyers to the user manual instead of helping them directly. Additionally, we haven’t had any dealings with ERAY, so we can’t give you any feedback on how their customer service is (we will if we have to deal with them).  

What Materials Can the ERAY P1 Thickness Guage Be Used On?

The P1 has two prob modes, Fe and NFe. The first mode gives you the ability to measure coating thicknesses on magnetic materials such as steel and iron. The second mode is used for non-ferrous (non-magnetic) materials such as copper and aluminium. The P1 can not be used on materials such as plastic.

Does the ERAY P1 Damage the Coating?

No, unlike some other thickness gauges out there the ERAY P1 is non-destructive, so you won’t do any damage to the coating/paint you want to measure.

What are the Specifications of the ERAY P1?

Probe ModeAuto/Fe (Ferrous)/NFe (Non-Ferrous)
Measuring Range0 to 2000μm (0 to 78.7mils)
Unitsμm, mm, mils
Min Curvature Radius Convex5mm
Min Curvature Radius Concave25mm
Min Measuring AreaDiameter 20mm
Min Thickness of Substrate0.2mm (Probe F); 0.05mm (Probe N)
Max Measuring Rate2 readings per second
InterfaceUSB (Micro)
Power Supply2 x 1.5V AAA battery
Standard ComplianceCE ROHS FCC ISO2178 ISO2360
Dimensions110mm*53mm*24mm (4.33″x2.09″x0.94″)
Net Weight92g (3.24oz)

First Impressions and What’s in the Box

Inside the fairly plain carboard box the ERAY P1 comes packaged in you get the following:

1 x Coating Thickness Gauge
1 x Aluminium Sample/Substrate
1 x Iron Sample/Substrate
5 x Standard/Calibration Foils
2 x AAA Battery
1 x USB Cable
1 x CD Software
1 x Tool Box

The hardshell toolbox/carry case the ERAY P1 comes in is quite sturdy and we feel it should protect the thickness gauge quite well. Additionally, the inside is padded so the gauge shouldn’t jump around when carrying and moving it around.

We were quite surprised at the size of the ERAY P1 thickness gauge given the size of the carry case. The case is quite compared to the gauge, but we quickly realised this was due to the fact that there are storage areas for the cable, calibrating substrates, batteries, etc.

The P1 gauge itself feels pretty good quality. We purchased the grey model, but a green version is also available as well. It has a plastic finish with a grippy texture on the sides. The buttons don’t feel fantastic, but they are more than good enough and easy to operate with gloves on.

Above the control buttons is a small LCD screen that displays information such as the current probe mode (Auto, Fe, NFe), the units that the gauge is currently reading in and more.

At the top of the gauge is a micro-USB port. We would have liked this to have been a USB-C port given that it is now 2023 and USB-C has been the standard for a number of years now. However, this is only a minor problem and if they do introduce a newer version at some point it would be good to see this change.

Operating the ERAY P1 Coating Thickness Gauge

While you are probably meant to calibrate the thickness gauge first, we couldn’t wait to start measuring, so we just turned it on and got probing. After hitting the power button you’ll need to give the ERAY P1 about 3 to 4 seconds to power on. Once the loading bar is complete and the welcome screen is gone you can begin measuring.

To measure the thickness of a coating you simple press the gauge against a surface and wait for the beep. Once this has happened the mean, minimum and maximum thickness reading will be displayed on the screen. It is very important to try and get the gauge as straight on to the surface as possible to get the most accurate result. There is a bit of practice involved here but you will soon get the hang of it if you haven’t used a gauge like this before.

As you can see from this photo the measurement can be quite far off if you don’t get the probe straight on to the surface.

You can also continuously measure the surface by placing and holding the probe against it. This lets you take multiple readings at the exact same point and then you can go into the “Recall” section in the menu and view them.

Once we had a quick play around with the P1, we decided to go ahead and calibrate it. Before we had purchased the ERAY thickness gauge we had read a couple of reviews from buyers who stated they had issues with calibrating the device or that they found the calibration process difficult. In truth, we actually found it very easy if you follow the included steps in the user manual and make sure to keep the probe head 90 degrees to the calibrating surface.

ERAY includes two uncoated samples, one aluminium and one iron, for calibrating the P1. They also provide you with what they call “calibration foils”. There are five of these foils in various different thicknesses and they are designed to mimic the surface of an actual finish.

The first step when calibrating the P1 thickness gauge is to press the “Zero” button and then probe one of the uncoated samples. Raise the gauge after you hear the first beep and repeat. Once you have done this a few times you press the “Zero” button again to exit out of this calibration mode. You then press the “CAL” button and place one of the calibration foils on the uncoated sample. Use the gauge to measure the thickness of the foil and then compare what is on the screen to what is on the foil. You can then adjust what the screen reading is by using the up and down arrows. Repeat the process until you match the measurement on the calibration foil or at least get within 1% of it.

As we stated above, we found this to be surprisingly simple and it only took a few minutes to get very accurate readings. Uncalibrated, the gauge was about 3 – 4% off, but we easily got that down to well under 1% with some very quick calibration. This was a massive plus to us as we were really impressed with just how accurate the ERAY P1 is given that it is not professional level gauge.

How Does the ERAY P1 Work on Cars and Other Vehicles?

Measuring the thickness of a car’s paintwork/finish is probably going to be the primary use case for most of the buyers of this gauge, so how does it perform? Well, as we mentioned just above it is very accurate after a quick calibration, so it will be great if you want to use it during a used car inspection, prior to a repair, etc.

If you want to get a good base reading of a car’s paint finish it is generally recommended that you use the door jam area. This is where the paint/clearcoat is usually the thinnest, so if you get readings lower than here it is probably a sign of an issue. Alternatively, if you find an area or areas that are quite a bit thicker than the rest of the car’s finish, it is a good sign that some work has been done to the car.

You can then use this information when discussing the price and whether or not you want to purchase the vehicle. This could easily save you more than the price of the ERAY thickness gauge, which is why we bought one for ourselves.

What Other Features Does the ERAY Have?

The ERAY P1 has a few extra features that are quite useful. The first of which is the ability to set a maximum and minimum reading. To do this you simply press the left button with a dot on it and then go down to limit. You then can go into the “settings” section and set the high and low values. If you want to remove the limit you then press the clear button.

The only problem here is we found that setting the desired limit can be a bit finicky. You have to use the down and up arrows to cycle through the different values until you get to the desired measurement/limit. It would be nice to be able to select the different digits individually and then cycle through them a bit like when you are selecting a date/time on your phone. However, it’s not a major problem and is really only an issue when you first set it up or after you clear the limit (the upper limit starts at 2100 μm).

Does the ERAY P1 Record Data?

By default, the P1 thickness gauge is set to what ERAY calls Direct Group or DIR mode. In this mode, readings are stored temporarily in the ram. You can check these readings in the “Recall” section of the main menu (Eray calls the main menu the “Root”). However, if you turn the gauge off, these readings will be lost.

Obviously, this isn’t ideal, so ERAY included the ability to select another Group Mode that allows you to store data for a longer period of time. You have to go into the Root menu and then select “Options”. From there you go into “Group Mode” and select one of the four General options (General 1, General 2 and so on). When you take a measurement, it is then stored in the General group you selected.

Up to 80 readings can be stored in each General group and if you go over that it simply overwrites previous measurements. We feel that 80 readings is more than enough for what most people will need the ERAY P1 for, especially as there are four groups, so you can have a total of 320 readings.

We found that the best way to use this feature is to use one group for the base measurements and then another group for the other measurements. Alternatively, you could take a base measurement and take a photo of it on your phone or note it down, and then take the other measurements. This way you don’t risk overwriting it if you accidentally go over the 80 readings limit.

Overall we had absolutely no problems here and it is really handy to have the ability to store so many readings, especially when using the gauge on something like a car.

Transferring Data to a PC?

ERAY claims that you can transfer data from the P1 Thickness Gauge to a PC, and in the box they include a USB cable to do this. However, we couldn’t test this ourselves. The software seems to be loaded onto a Mini CD and we couldn’t find it online. Seeing as our computers (and probably most peoples today) don’t have CD drives this is a bit of an oversight on ERAY’s part.

Sometimes, simply plugging in a device will find the drivers on Windows, but this didn’t work for us and we couldn’t access the data. We think it would be better if ERAY could provide a download link on their website, so those that don’t have a CD drive available can install the software easily.

We weren’t too disappointed by this as we probably won’t actually use this feature, but if you plan to connect the gauge to your PC, keep this in mind. Another thing to note is that the software is not compatible with MacOS and other operating systems, just Windows.  

What Languages Are Available?

In the options menu there are only options available for English and German. We were quite surprised at this and thought there would be a few more (especially Chinese as that is where the ERAY P1 comes from).

Is the ERAY P1 Coating Thickness Gauge Reliable?

Yes, in our experience. We haven’t had any reliability problems with the ERAY P1 during our period of testing, but as always we will update this review if we have any problems. Additionally, we could only find a couple of reports of failures from other reviews online, which seems to be a very low number given how many of these gauges have been sold.

Conclusion – Should You Buy the ERAY P1 Thickness Gauge?

The initial outlay for this gauge is reasonably high at just over $100, but we think it is worth it. This gauge could easily save you that amount of money and much, much more during a used car inspection, and that is why we got one.

The gauge is very accurate once calibrated (key point being once calibrated) and is pretty easy to use once you get the hang of it. We aren’t massive fans of the plastic build and the slightly mushy buttons, but it is very compact and light.

The main annoyance for us is the inability to transfer data to a PC as we can’t install the software. This would be easily solved by providing buyers with a download link to the software rather than including a Mini CD in the box when almost no-newer computers come with a CD-drive any more. However, the General Groups allow you to store quite a lot of readings, so this isn’t a major problem for us.

Overall, we definitely recommend the ERAY P1 Thickness Gauge. While not perfect, the great features, accuracy and ease of use more than make up for a few minor inconveniences.


  • Ben

    From his early days playing the original Gran Turismo and with his Hot Wheels car set, Ben has had a long interest in all things automotive. His first foray into the world of automotive journalism was way back in 2009 and since then he has only grown more interested in the industry. Ben also runs and heads up the video production side of Garage Dreams, focusing on small informative documentaries about some of the world's most legendary cars.

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