Abrasive Blasting & Surface Preparation · Westforge Works
Why coatings fail: it is almost always preparation
When a coating fails early, the product is rarely the cause. Preparation, film thickness and application conditions account for the overwhelming majority of failures.
5 min read · Reviewed 2026-01-12
Contamination under the film
Oil, grease, release agents, soluble salts and dust all prevent adhesion. Some are invisible. Blasting removes coating and corrosion but does not remove oil — degreasing has to happen first, or the abrasive simply drives the contaminant in.
The wrong profile
Coatings need a mechanical key. Too smooth and there is nothing to grip; too coarse and the peaks sit proud of the film, leaving thin spots that corrode first.
Profile is set by media choice and pressure, which is why the medium is matched to the coating system rather than to whatever is loaded.
Coating outside its conditions
Every coating has a temperature, humidity and dew-point window, and a maximum time between preparation and coating. Blasted steel left overnight in coastal air has already begun to flash-rust.
This is the practical argument for preparation and coating happening in the same workshop, in sequence.
Thin film where it matters most
Coating pulls away from sharp edges, weld toes and corners as it flows. Those are exactly the points most exposed to damage and moisture, so they are where failure starts.
- Dress sharp edges before coating where the design allows
- Stripe-coat edges and welds on high-exposure work
- Check film thickness at edges, not just flat faces
Common questions
Why did my powder coating peel after a year?
Adhesion loss almost always traces back to contamination or insufficient profile at preparation, not the powder itself.
Can you coat over rust if it is only light?
No. Light rust still separates the coating from sound steel and continues underneath the film.
How soon after blasting should coating go on?
As soon as practical and within the coating system's stated window — blasted steel starts to flash-rust quickly in humid coastal air.