Surface profile, explained without the jargon

Every industrial coating datasheet specifies a surface profile. Most people skip that line. It is the line that decides whether the coating stays on.

What profile is

Blasting does not just clean steel, it roughens it. Each particle of media leaves a tiny crater. The resulting texture — peaks and valleys across the surface — is the profile, and it is what a coating mechanically keys into.

It is measured peak-to-valley, in mils (thousandths of an inch) or microns. A typical industrial spec asks for something like 2 to 3 mils.

Why too little fails

A smooth surface gives the coating nothing to grip. Adhesion then relies entirely on chemical bond, and on steel that flexes, heats and cools that is not enough. The coating lets go in sheets rather than blistering.

Why too much also fails

An excessive profile means the peaks are taller than the coating is thick. Those high points end up with almost no coverage over them, and they are exactly where corrosion restarts. You get pinpoint rusting across an otherwise sound film.

Profile is a specification with a range, not a target to exceed. More is not better.

What controls it

Media type, media size, pressure and standoff distance. Angular media cuts a deeper profile than rounded. Bigger media cuts deeper than fine. That is why the media selection follows the coating spec rather than the other way around.

This is the specification the coating shops and fabricators in Brier Park Industrial and out in Redcliff will ask you about before anything else. If the profile is wrong, nothing applied over it performs to its data sheet.