Measuring and Layout — FAQ
What is a thickness gauge used for?
Thickness gauges measure material wall thickness, coating depth, or gap width. Automotive versions detect paint layers to identify collision damage. Industrial models verify pipe walls and casting integrity. Mechanical gauges check weld gaps and slot dimensions. Each type serves specific quality control and inspection applications.
Digital vs ultrasonic thickness gauges—what's the difference?
Digital coating gauges measure non-magnetic coatings on metal surfaces using magnetic induction or eddy current. Ultrasonic gauges send sound waves through materials to measure total wall thickness from one side. Digital gauges work for paint and plating; ultrasonic gauges measure solid materials like pipes, tanks, and castings.
How accurate are budget thickness gauges under $15?
Quality budget gauges deliver ±3% accuracy or better—sufficient for most inspection and hobbyist needs. Our top pick achieved ±1% repeatability on steel panels. Industrial ultrasonic models under $15 maintain ±0.1mm accuracy on thick materials. Accuracy degrades if calibration is skipped or batteries are low.
Do I need to calibrate my thickness gauge?
Yes. Digital coating gauges require zero calibration on bare metal substrate before measuring paint. Ultrasonic gauges need velocity calibration for each material type using a known-thickness sample. Mechanical taper gauges need no calibration but must be kept clean. Monthly recalibration maintains accuracy in professional use.
Can I use an automotive paint gauge to check for accidents?
Absolutely. Factory paint ranges 80-180 μm; readings over 250 μm indicate filler or repaint. Measure 10-15 spots per panel, comparing driver door readings to other panels. Consistently high readings reveal replaced panels or heavy bodywork. Our Best Overall pick auto-detects aluminum panels common on modern hoods and fenders.
What thickness gauge works on plastic and glass?
Ultrasonic gauges measure plastic and glass thickness from one side without damage. The Industrial-882 and Industrial Range models both include velocity presets for these materials. Coating thickness gauges only work on conductive substrates. Mechanical gauges cannot measure enclosed plastic or glass parts.
