Why Does a Coating Thickness Gauge Give Different Readings Malaysia
Why Does a Coating Thickness Gauge Give Different Readings Malaysia
Content
You place a coating thickness gauge on the same painted surface several times and get:
118 μm → 126 μm → 121 μm → 139 μm
Is the coating thickness gauge faulty?
Not necessarily.
Small variations can occur because coating thickness measurement is affected by the surface condition, substrate, probe position, calibration and the actual coating itself.
Understanding these factors is important when using instruments such as the UNI-T UT343A Coating Thickness Gauge for automotive, metal fabrication, painting and industrial inspection in Malaysia.
1. The Coating May Actually Be Uneven
Paint and protective coatings are not always perfectly uniform.
Different areas can have slightly different thicknesses because of:
Spray pattern
Application technique
Number of coating layers
Surface geometry
Previous repainting
Repair work
Manufacturing process
This is why several measurements should normally be taken instead of relying on only one point.
For example:
Point A: 115 μm
Point B: 118 μm
Point C: 117 μm
These readings show relatively small variation.
But:
Point A: 115 μm
Point B: 120 μm
Point C: 285 μm
The third location should be investigated further.
2. The Probe Is Not Sitting Flat
Probe position can affect measurement stability.
If the probe is tilted or does not make proper contact with the surface, readings may become less consistent.
Try to place the probe:
Perpendicular to the surface
Firmly but naturally
At a stable measurement point
Without sliding the probe during measurement
Repeat the measurement several times to check consistency.
3. The Surface Is Curved
Measuring a large flat steel plate is generally easier than measuring a very small or strongly curved component.
Curvature can influence how the probe sits against the surface.
This is especially relevant when measuring:
Pipes
Small metal components
Vehicle body contours
Corners
Curved fabricated parts
If readings change significantly near an edge or curve, compare them with measurements taken on a flatter section.
4. Dirt Between the Probe and Surface
Dust, oil, debris or other contamination can interfere with proper probe contact.
Before measurement:
Clean the measurement surface and inspect the probe contact area.
Do not assume every unexpected reading represents a coating problem.
Sometimes the measurement condition itself is the cause.
5. You Are Measuring Different Substrates
A coating thickness gauge needs to understand the material underneath the coating.
The UNI-T UT343A supports Fe and NFe substrates.
Fe generally refers to ferrous metals such as steel.
NFe generally refers to non-ferrous metals such as aluminium.
If you move between different components or panels, the substrate may change.
This is especially important in automotive and manufacturing applications where different metals can be used within the same product.
6. Calibration or Zero Checking May Be Required
If measurements appear consistently incorrect or unusually unstable, check the instrument according to the manufacturer's operating procedure.
Depending on the instrument and application, this can involve checking the gauge against an appropriate reference or uncoated substrate.
Calibration and measurement verification are especially important when results are being used for:
QA/QC records
Incoming inspection
Production control
Customer reports
Acceptance inspection
A gauge that powers on normally is not automatically guaranteed to be measuring correctly.
7. Measuring Too Close to an Edge
Measurements close to an edge may behave differently from measurements taken in the centre of a sufficiently large surface.
When possible, avoid immediately using an edge measurement as your primary reference.
Take several readings farther from the edge and compare the results.
8. One Reading Is Not Enough
A common mistake is:
Measure once → see a number → make a conclusion.
A better inspection method is:
Measure several points → compare readings → calculate or review the average → identify unusual areas → investigate further.
The UNI-T UT343A includes MAX, MIN and AVG functions, which can help users evaluate multiple readings.
Example: Checking Painted Steel
Imagine you are inspecting a painted steel enclosure.
Measurements are:
Location 1: 126 μm
Location 2: 129 μm
Location 3: 125 μm
Location 4: 128 μm
Location 5: 240 μm
Instead of immediately assuming the instrument is inaccurate, recheck Location 5.
Clean the surface, position the probe correctly and measure nearby points.
If the surrounding area also produces substantially higher readings, the coating itself may be thicker in that section.
UNI-T UT343A for Coating Thickness Measurement
The UNI-T UT343A Coating Thickness Gauge offers a measuring range of up to 1750 μm and supports both Fe and NFe metal substrates.
Key functions include:
Single measurement
Continuous measurement
Automatic substrate recognition
MAX/MIN/AVG
199 data storage
μm/mil selection
Upper and lower limit alarm
These functions make it suitable for applications such as:
Automotive paint inspection | Metal fabrication | Powder coating | Manufacturing | Maintenance | QA/QC
Coating Thickness Gauge Support in Malaysia
If your coating thickness gauge is producing unusual readings, first identify:
What coating are you measuring?
What is the substrate material?
Approximately how thick should the coating be?
Are the readings unstable everywhere or only in one area?
Providing this information makes troubleshooting much easier.
For users in Selangor, Kuala Lumpur, Johor, Penang, Melaka, Negeri Sembilan, Perak, Pahang, Kedah, Kelantan, Terengganu, Perlis, Sabah and Sarawak, contact MTM Precision for coating thickness gauge enquiries.
MTM Precision Sdn Bhd
Showroom & Service Centre: Puchong, Selangor, Malaysia
Tel: 03-8080 7172
WhatsApp: +6016-660 7346
Email: mtmpre@yahoo.com
Website: www.mtmpre.com.my
Send us the instrument model, substrate type and several example readings if you need help identifying a coating thickness measurement issue.
22 Sep 2026
