Getting inaccurate readings from your coating thickness gauge? Don’t assume the tool is broken.
In our experience, most bad readings come from simple, fixable errors in the process. Accurate coating thickness measurement requires both the right tool and the right technique.
Before you scrap a part, check for these
Top 3 Common Errors in Coating Thickness Measurement (And How to Fix Them)
Error 1: Improper or “Forgotten” Calibration
This is the #1 cause of bad readings. Your gauge is a precision instrument; it needs a baseline “zero” to be accurate.
Why It Happens:
- You “zeroed” the gauge on your workbench, not the actual part.
- The gauge has “drifted” due to temperature changes or heavy use.
The Fix:
- Calibrate on the bare part: Always “zero” your gauge on an uncoated spot of the exact part you are testing.
- Use shims: If you don’t have a bare part, use certified shims on the uncoated substrate to check accuracy.
- Re-calibrate often, especially if you change materials or environments.
Error 2: Measuring on the Wrong Substrate (F vs. N)
A gauge for steel (F) won’t work on aluminum (N). They use different technologies.
Why It Happens:
- You’re using an “F” (Ferrous/magnetic) gauge on a non-magnetic “N” (Non-Ferrous) metal like aluminum, or vice-versa.
- You’re not sure what the base metal is.
The Fix:
- Know your substrate: Use a magnet. If it sticks, it’s Ferrous (F). If not, it’s Non-Ferrous (N).
- Get a dual “FN” gauge: The best solution is a combination coating thickness gauge. It auto-detects the substrate and uses the right technology, every time.
(Read more in our guide: How to Choose a Gauge: Ferrous vs. Non-Ferrous)
Error 3: Poor Operator Technique
How you handle the probe is critical.
Why It Happens:
- “Rocking” the probe: You aren’t placing the probe flat (90°), causing it to “rock” on one edge and create a gap.
- Dirty or rough surfaces: The probe can’t seat flat.
- Relying on one reading: A single measurement is not reliable.
The Fix:
- Place it flat: Seat the probe firmly and flat on the surface. Don’t scrub or twist. Just place, measure, and lift.
- Clean the surface: Wipe away any dust, oil, or debris.
- Take an average: The professional way to get a true coating thickness measurement is to take 3-5 readings in a small area and average them.
Get an Accurate Reading, Every Time
Don’t let these simple errors cost you time and money. Following these steps will ensure your coating thickness gauge readings are accurate.
If you’re still getting bad results, your gauge may be old or damaged. It might be time for an upgrade.
Need a gauge you can trust? Our technical experts are here to help. Browse our full range of Coating Thickness Gauges or contact us for a free consultation.
