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Measuring the Thickness of the Paint Layer
The forerunners of the used car salesmen were the horse dealers. Even then, they even went as far as painting the teeth of an old nag, to give the impression of health and
staying power. Only 30 years ago the sidewalls of tyres were dyed black, regardless of how worn down they were. Painting has always been a means of making the object
to be sold a bit more attractive.
For this reason, we can be glad that there are instruments on the market today, which don't cost the earth, and mercilessly uncover such attempts at fraud. After all, an
original factory paint-job is only a little less than 1/10 of a millimeter thick, which makes respraying in the same thickness almost impossible. The device of course, also
detects putty-filler and other similar nonsense.
Of course the varnish thickness on non-ferrous materials is also determinable, as is a metallic coating. Here one can establish, whether e.g., through galvanisation or
electro-plating, a layer has been evenly applied. Most coating-thickness measuring instruments can be calibrated according to ISO guidelines. Thus, a workshop can
include and calibrate the instruments in it's ISO-testing equipment pool, ensuring a constant and accurate measuring.
The layer thickness is sometimes also determined on relatively small surfaces. Also important here, as in fact with all measurements, is the calibration. This allows, should
the situation arise, that another instrument would theoretically, provide the same result when testing exactly the same area. By the way, this is also why, when measuring the
paint-layer-thicknes, sometimes mountings or tripods are used.
Some devices are switchable. They then measure, e.g., the paint thickness on ferrous materials using a magnetic-inductive process. Using the whirlpool process the
thickness of a layer of paint on zinc could then be determined. Zinc would not react to the magnetic attraction provided by the primary coil of an electro-magnet, would
however, significantly alter a whirlpool.
At this point it must be stressed, that all inspections are carried out without causing any damage. The same as the third (and more seldom) method, where the reflection of
ultra-sonic waves are evaluated. Here it is possible to take measurements from only one side. The combination of various methods determines several layers of paint and
metal, one on top of the other. 07/11
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