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Best tests for galvanizing coating weight?

We are installing a new galvanizing line and the question has come up on the methods used to check the coating weight. The only method we have been asked about is "weigh-strip-weigh". Is this best method or is there comparison information about the different methods?

Jim Humpolick
project manager - Ukranie
2007

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First of two simultaneous responses --

The weigh - strip- weigh method is a destructive one. It only tests what the coating weight WAS, as after the test there's no coating.

Far more practical is the magnetic systems which use a small handheld device that non-destructively test for thickness over the steel. Readout in microns (or other units), with reasonable accuracy to about ± 3 microns.

Geoff Crowley
Crithwood Ltd.
Westfield, Scotland, UK

2007

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Second of two simultaneous responses -- 2007

Sir:
A "banana" permanent magnetic thickness gauge made in the USA or Germany gave best precision and accuracy in the 300,000+ test readings that I published in the split article in the journal Metal Finishing. The electronic, more expensive gauges gave lower precision.
Regards,

Dr. Thomas H. Cook
Galvanizing Consultant - Hot Springs, South Dakota, USA

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