How to calibrate the Elcometer 456 Coating Thickness Gauge
It is vital to calibrate your coating thickness gauge to achieve the highest level of measurement accuracy.
Calibration adjustment is the process of setting the gauge to known values of thickness to ensure accuracy on different substrate types, shapes and surface finishes.
The coating thickness gauge can be calibrated using several different methods. The gauge can be calibrated for use in accordance with National and International Standards or to a specific application.
The Elcometer 456 Coating Thickness Gauge is factory calibrated, but to get the best performance from the gauge, and make best use of the gauge’s ±1% accuracy, the gauge should be calibrated to suit a specific application, using the gauge’s internal calibration routines.
A range of calibration options are available on the Elcometer 456 Coating Thickness Gauge.
Zero Calibration is a simple method for calibrating on smooth substrates and is sometimes referred to as ‘Single Point Calibration’. Following the on-screen calibration instructions, place the probe on the uncoated metal substrate, making sure you have 100% contact with the surface. The gauge will adjust the calibration automatically, and is ready to start measuring coating thickness.
Smooth Calibration is a more accurate method than the single point or zero method, as the gauge is calibrated using a calibration foil and the un-coated substrate. Calibration foils or ‘shims’ are the most convenient way of creating a coating thickness standard on the substrate material, surface finish or shape. Smooth Calibration is the ideal method for adjusting the calibration of the coating thickness gauge to ensure the greatest possible accuracy.
Rough or 2 Point Calibration
Rough or 2 Point Calibration is the ideal method for calibrating the gauge on rough or blasted profiled metal substrates or for substrates where there are significant differences in the magnetic or electrical properties of the substrate. This calibration method requires 2 foil values – one should be a value above the target film thickness and one below. Simply follow the on screen instructions to calibrate your coating thickness gauge.
Zero Offset Calibration
Zero Offset Calibration is a patented calibration method to help measure film thicknesses according to ISO 19840. The calibration uses the smooth surface technique, and a correction value (zero offset) is applied to each reading to account for the effect of the roughened surface; the value of the offset depends on the initial surface profile and is described in ISO 19840.
This is a calibration method unique to the Elcometer 456 Coating Thickness Gauge and has been designed to simplify and speed up the calibration process for users who are calibrating their gauge using the same foil values each time.
In addition to the standard calibration methods, the Elcometer 456 Coating Thickness Gauge has four pre-defined calibration methods which follow relevant standards: ISO, SSPC PA2, Swedish and Australian Standards. These not only define the calibration method to be used, but also set up the data collection method, as defined by the appropriate standard.