Problem Solving Forum
August 28 - September 1, 2017
Is there any method to take accurate wet film thickness readings when applying zinc rich primers?
Marco Fabio Ramenzoni of ZINGA METALL BRASIL on
September 1, 2017:
Definitely, for IOZ, the testing plates are the mo ...read more Definitely, for IOZ, the testing plates are the most effective way to reach target DFT, as WFT is close to impossible to be PRECISELY measured. The finding of the DFT per pass before the actual application is, above all, very useful and convenient. For organic zincs, the measurement is mostly direct and easy through the traditional measurement methods (like the Wet Film Combs), even with a 96% pure zinc content in the DFT.
Larry Muzia of Exceletech Coating & Applications, LLC on
August 29, 2017:
I agree that taking wet film readings on an inorga ...read more I agree that taking wet film readings on an inorganic zinc is somewhere between very difficult to suspect. In addition to the rapid drying of the inorganic zinc, it is filled with metallic zinc, which does not compress under the outer edge of the wet film gauge and instead packs up under the edge, so using a test plate to spray on is a reasonable idea as well as experience in applying zincs.
richard d souza of stoncor middle east llc on
August 27, 2017:
An IOZ silicate primer has approx 40-50% of pores ...read more An IOZ silicate primer has approx 40-50% of pores by volume and dries so quickly that accurate WFT readings are uncertain. Hence, my practical way is to use mock-up plates before the actual application and judge the dft achieved per pass, or number of passes needed to achieve required or specified dft and more or less stick by the number of passes per defined dft. Allowance must be made for for extra consumption due to filling of surface roughness and loss due to structural configuration and wind velocity during actual spraying.