Magnetic materials can be classified according to their permeability coefficient.

Diamagnetic materials 0 < μr < 1
Paramagnetic materials > 1 Ferromagnetic materials ? 1

Measurements with List-Magnetik's permeability meters can only be carried out on paramagnetic substances. For example, paramagnetic are aluminum, chrome, platinum and stainless steel. For stainless steel, the value μr depends on the alloy.

Ferromagnetic materials (iron, nickel, cobalt and various alloys) have a permeability coefficient that is much greater than 1 and can assume values of more than 100. Such substances significantly increase the magnetic flux density of a magnetic field. List-Magnetik's permeability meters are not designed for this.

The measured value of permeability depends on the dimensions of small samples. The sensitivity of the instrument increases with the thickness of the sample.
From a sample thickness of about 5 mm and a lateral expansion of about 2 cm, the measurement is independent of the size.
The approximate dependence of the sensitivity on the sample thickness is shown in the diagram.
The sensitivity is calculated as (μr indicated – 1) / (μr true – 1)

With the calibration standard supplied with the instrument, you can check the accuracy of the measurement at any time. The standard calibration standard has a value of μr ~ 1.35. Additional calibration standards with reference values of μr ~ 1.03 and μr ~ 1.11 are available.