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What Does too much Surface Profile Cost?

Posted in Painting & Coating

Using coarse abrasive can cost you more than you think

Coating Ship
Coating applied to small ship hull.

Having a profile that is larger than the minimum allowed in the specifications will cost you when it comes to paint.

Lets give an example:

A 10,000 ft2 area of steel with a 50 micron profile requires approximately 80 liters of paint to fill up the profile before starting a film build. This takes into account 79% volume solid and a transfer efficiency of 75% using and airless spray gun.

An inorganic zinc coating costs, say, $16 a liter this is equivalent to $1,280 of coating.

If you increase the profile to 75 micron this is uses 50% more coating which is and extra %640 cost.

The Pitfalls of Surface Profile

Excess Profile: While an absence of profile can be detrimental to coating adhesion, it can be equally disastrous to have an excessive profile height causing premature rusting and coating failure. In addition, more profile means using more paint to cover the surface!

Consider these cases:

Rule of Thumb #1 - Profile height should not exceed the primer coat DFT (Dry Film Thickness).

Rule of Thumb #2 - Profile height should not exceed the total coating system DFT.

Embedment: Embedment of abrasive particles in the surface is a threat posed by friable, irregular shape abrasives. The embedded particle or fragment can stand out as a ‘rogue’ peak above the surrounding profile and may protrude through the applied coating.

Surface Profile Coating
1 mils (25 Micron) Primer
Surface Profile Coating
2 mils (50 Micron) Primer
Surface Profile Coating
3 mils (75 Micron) Primer