Understanding Surface Profile in Blasting


CONTENTS
0:04 – What is surface profile?
1:32 – Surface profile vs. roughness
2:01 – Why does the coatings industry measure surface profile?
2:58 – What surface profile is required?
4:31 – Surface Comparators
4:59 – Replica Tape
5:44 – The new Elcometer 224 Digital Surface Profile Gauge
7:06 – Why you need to take multiple readings
8:39 – The Elcometer 224 and ElcoMaster App

In the industrial and protective coatings industry, steel surfaces are blasted not only to remove corrosion or old coatings, but to generate a surface profile prior to re-painting.

The surface profile increases the surface area, and it is this increased surface area which provides a key for the coating to adhere or stick to.

Surface Profile should not be confused with roughness. Surface profile is a measurement of the peak-to-valley height. Surface roughness, on the other hand, is the combined measurements of the surface profile and the frequency of the peaks across a linear length (also known as the peak count).

The coatings industry measures surface profile to avoid corrosion. Corrosion is typically caused when three things come together – a ferrous material (in our case the steel substrate), oxygen (from the air) and moisture. If you can remove just one of the 3 elements, corrosion (or more precisely aerobic corrosion) simply cannot happen.

Applying a coating to the steel provides a barrier between the steel and both the air and moisture, preventing corrosion. So if the coating is damaged, or simply rolls off the surface due to poor adhesion, then the steel will rust, corrode, and in time weaken the structure.

The surface profile required is specified by the coating manufacturer or the coating specification agreed to by all parties, and is directly related to the specified dry film coating thickness being applied.

Typically the surface profile specified is the peak-to-valley height in either microns or mils. The coating is also specified in either microns or mils, as a dry film thickness. The key here is that the required coating thickness is applied to both the valleys and the peaks, otherwise you get rust spots. If the profile is too high or too low, this can lead to premature coating failures, and ultimately corrosion.

Other method:

Replica tape method : Details will publish in next post keep watching

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