Zinc coatings having thicknesses of more than 5μm under the paint, especially with car bodies, present an essential additional protection against corrosion. The zinc coating does not offer any significant protection against corrosion when under 5μm. With all our combination instruments belonging to the Surfix® family you look through the paint non-destructively and clearly determine whether the zinc coatings are more than 5μm or if no zinc coating exists.