Measurement of Cr/Ni/Cu coatings on plastic substrates

Bathroom fittings are commonly finished with a decorative chromium plating. But what may appear to be a solid metal shower head, for example, is often just a multi-layered metal coating on top of a plastic substrate. To guarantee that the shower head not only look pretty when delivered but even after many years of usage, the thickness of each individual layer must be controlled to ensure quality.

The typical composition of such shower heads is a chrome/nickel/copper coating system on top of a plastic substrate material. The decorative chromium outer finish is usually only 0.5μm thick (or less) and the nickel layer about 5-10μm. If the copper layer is between 20-25μm, making the overall coating thickness no more than 30μm, non-destructive measurement using the x-ray fluorescence (XRF) method is possible.