Selecting quality measuring equipment for checking paintwork becomes a critical step when purchasing a used car or inspecting body repairs. Among the many Chinese and European brands, the model ETARI ET 555 deserves special attention due to its versatility and advanced functionality. This device belongs to the class of magnetic induction and vortex sensors, which allows it to work with a wide range of metals.
The main task of this device is to identify secondary paint, putty and manufacturing defects without damaging the surface. Unlike budget analogues, ET 555 offers the user not just reading numbers, but a full analysis of the condition of the body with the ability to build graphs and statistics. Understanding how this gadget works will help you avoid buying a “damaged” car or overpaying for poor-quality repairs.
In this article we will analyze in detail the technical characteristics, operating features and nuances of calibrating the device. You will learn how to correctly interpret readings on different types of metals and why it is important to consider temperature conditions when working. Proper use ETARI ET 555 turns it from a simple “measurement” into a powerful tool for an expert auto selector.
Technical characteristics and design features
The device is based on a modern element base that ensures high sensor response speed. The case is made of impact-resistant plastic with rubberized inserts, which prevents slipping in the hand and protects the electronics from light impacts. The display of the device has high contrast and backlighting, which makes reading readings comfortable even in poorly lit conditions of the garage or in bright sunshine.
A key feature of the model is the presence of two independent measurement channels, which allows you to work with ferromagnetic (steel) and non-ferrous (aluminium) metals without manually changing the mode. The system automatically detects the type of substrate, although in some cases forced switching through the menu is required. The measurement accuracy is stated by the manufacturer to be within ±2-3% or ±2 microns, which is an excellent indicator for devices in this price segment.
⚠️ Attention: The device sensor is sensitive to strong magnetic fields and sudden temperature changes. Do not leave the device on your car's dashboard in direct sunlight on a hot day as this may cause readings to drift or damage the screen.
Ergonomics ETARI ET 555 designed for long-term operation: the weight of the device is minimal, and the location of the buttons allows you to operate it with one hand. Power is supplied from a built-in lithium-ion battery, which is charged via a standard micro-USB or USB-C connector (depending on the year of manufacture). The battery charge lasts for several thousand measurement cycles, which covers the needs of even a professional picker for a full working day.
Operating principle and types of measured surfaces
The fundamental basis of the device's operation is to record changes in the electromagnetic field. For steel body elements, the magnetic induction method is used: the sensor measures the force of magnetic attraction or the change in the inductance of the coil depending on the distance to the metal. The thicker the paint layer, the further the sensor is from the metal, and the weaker the signal.
For aluminum parts such as hoods, trunk lids or doors of premium cars, the eddy current method is used. In this case, the coil generates a high-frequency electromagnetic field, which induces eddy currents in the non-ferrous metal. The parameters of these currents directly depend on the thickness of the dielectric layer (paint) between the sensor and the metal. ET 555 automatically switches signal processing algorithms, providing correct data.
It is important to understand the limitations of the device when working with complex surfaces. The device is not intended for measuring the thickness of liquid varnishes, rubber or plastic without a metal base. Errors may also occur on highly curved surfaces or in areas with complex geometries where there is insufficient sensor-to-surface contact area.
Effect of body geometry on accuracy
On sharp edges of the body and in deep grooves, the contact area of the sensor is reduced. This may lead to underestimation. It is recommended to take several measurements around the defective area and average the result, moving away from the edge of the part by at least 1-2 cm.
When working with combined materials, for example when an aluminum panel is glued to a steel frame, the device may show unstable results. In such cases, experienced specialists recommend manually selecting the operating mode through the menu, forcibly setting the type of metal if the automation fails. This allows you to get a more predictable picture of the condition of the paintwork.
Instructions for calibrating and setting up the device
Factory calibration ETARI ET 555, as a rule, is made qualitatively, but to achieve maximum accuracy or work in specific conditions, it is recommended to carry out user calibration. This process is especially important if you are working on vehicles whose factory paint thickness differs significantly from the average, or if the sensor has been subjected to impacts.
The calibration procedure is performed using the reference plates and films included in the package. First, a “zero” calibration is performed on a clean metal plate (usually iron and aluminum). Then calibration films of known thickness are applied, and the device remembers these values. This allows you to adjust the sensor error for specific operating conditions.
☑️ Checklist for correct calibration
A function to reset all settings to factory values is available in the device menu. This action is useful if, during the experimental setup, incorrect data was entered that could lead to systematic errors. After the reset, you must go through the initial setup procedure for the language, units of measurement and date format again.
⚠️ Caution: Never perform calibration on dirty, oily or oxidized surfaces of the reference plates. Even a microscopic layer of fat can distort basic readings and render subsequent measurements on the vehicle useless.
Interface and working with the device menu
Menu navigation ET 555 implemented through a combination of buttons and a logical nesting structure. The main screen displays the current thickness value, units of measurement (µm or mils) and operating mode. To access advanced functions, you must hold down the corresponding function key or use the button combination described in the manual.
In the settings, you can change the units of measurement from micrometers (µm) to mils (mils), where 1 mil = 25.4 microns. This is convenient when working with American technical documentation or communicating with colleagues who use the imperial system. It is also possible to configure the threshold of the sound signal, which is triggered when the specified thickness value is exceeded, which speeds up the initial inspection of the body.
The statistics function allows you to view the maximum, minimum and average value of a series of measurements. This is extremely useful for assessing the uniformity of paint application. If the spread of values on one part is large, this is a direct sign of a repair or a factory paint defect. Data can be sorted and grouped by body elements.
To quickly navigate through the measurement history, use the “Favorites” function or mark critical points. This will allow you, after inspecting the entire vehicle, to quickly return to suspicious areas and conduct a repeated, more thorough diagnosis.
Comparison of indicators and table of paintwork standards
Interpretation of the data obtained requires an understanding of factory paint thickness standards. Factory values may vary depending on the vehicle make, year of manufacture, and even the specific assembly plant. Typically, the factory paint thickness is in the range from 80 to 140 microns, but on some parts (stiffeners, sills) it can be thinner, and on horizontal planes it can be thicker.
Exceeding values up to 200-250 microns often indicates a second layer of paint or poor-quality factory application. Readings above 300 microns almost always indicate the presence of putty. However, it is important to consider that on some premium cars the factory thickness can reach 180-200 microns, which is the norm for this brand.
| Coverage type | Thickness (µm) | Probable Cause | Recommended Action |
|---|---|---|---|
| Factory paintwork | 80 - 140 | Standard paint | No action, normal |
| Secondary coloring | 150 - 250 | Cosmetic repairs, repainting | Visual inspection, checking transitions |
| Putty (thin layer) | 300 - 600 | Removing dents and scratches | Checking with a magnet, searching for repair boundaries |
| Putty (thick layer) | > 1000 | Serious accident, geometry | Refusal to purchase or in-depth examination |
When analyzing the table, it is worth remembering that the values are averaged. For example, on French-made cars, the factory thickness is often higher than on Japanese cars. Therefore ETARI ET 555 should be used in conjunction with visual inspection and knowledge of the specifics of a particular brand. A sharp jump in readings on adjacent body elements is a sure sign of repair.
Typical measurement errors and their elimination
One of the most common mistakes is measuring on a contaminated surface. Dust, dirt, water or wax create an additional gap between the sensor and the varnish, which leads to artificially high readings. Before each measurement, wipe the surface with a dry soft cloth. This simple action often changes the diagnostic picture dramatically.
Another error is the incorrect angle of the sensor. To obtain correct data, the sensor plane must fit tightly and evenly to the surface being measured. On radius surfaces (fenders, bumpers), you should choose the most even area or take several measurements with different rotations of the device, choosing the minimum stable value.
⚠️ Warning: Do not attempt to measure paint thickness on plastic bumpers using magnetic mode. Plastic is not metal and the readings will be erratic or zero. There are ultrasonic thickness gauges for plastic, but ET 555 only works with metals.
Also, users often ignore temperature compensation. If you move the device from a cold place to a warm room, condensation and changes in the properties of the electronics may cause an error. Allow the device to acclimate for 15-20 minutes before operating. This will ensure stable readings and extend battery life.
The main secret of accuracy is the cleanliness of the surface and tight pressure of the sensor. 90% of beginners’ mistakes are associated precisely with ignoring these two factors, and not with a malfunction of the device itself.
Frequently asked questions (FAQ)
Can the ETARI ET 555 be used to measure paint thickness on wood or plastic surfaces?
No, this device works exclusively on a metal base (ferromagnetic or non-ferrous). To measure the thickness of coatings on dielectrics (wood, plastic, glass), instruments with ultrasonic or eddy current methods, specially designed for such materials, are required. On plastic ET 555 will not give evidence.
How often should the thickness gauge be calibrated?
It is recommended that professionals perform a calibration check before the start of each work day or when temperature conditions change. For home use, it is enough to calibrate the device upon purchase, after a fall or shock, or if you notice instability in the readings on the reference plates.
What should I do if the readings on one part are very different (for example, 100 and 400 microns)?
This scatter indicates local repairs in this area. It is necessary to carefully inspect the area with the maximum indicator from different angles of light for shagreen, dust in the paint or differences in shade. Most likely, a dent or through corrosion was repaired there.
Does the temperature of the car itself affect the measurements?
Yes, it does. A body heated in the sun may have a slightly changed paintwork structure, and cold metal interacts with the sensor differently. The optimal temperature for measurements is room or outdoor in the shade. Avoid taking measurements on a hot hood immediately after a trip.