Surface Preparation: The Foundation of a Coating that lasts

One issue we’ve come across time and time again is premature coating failure, and the main cause… surface preparation. 

It's not a glamorous topic. But if you manage assets that need to stay protected and in service, it's probably the most important thing to understand about industrial coatings. Poor performance is prevented by perfect preparation and industrial coating is no different. You typically don’t see a return on a paint job in the first few years. Its true value becomes clear after 5–10 years, when the asset remains corrosion-free, proving you did or didn’t choose a high-quality contractor.

Why surface prep drives coating performance

A coating is only as good as what it's applied to. No matter how well a product is formulated, if the substrate hasn't been properly prepared, the coating can't do its job.

When steel is blasted correctly, it creates a uniform surface profile, essentially a microscopic texture that the primer coat or direct to metal top coat can mechanically interlock to. A quality primer will rely on a combination of mechanical adhesion to the substrates surface profile and chemical adhesion, a molecular bond between the primer coats’ composition. 

Without the foundation of a surface profile, you're relying on chemical adhesion alone, which is nowhere near sufficient for the conditions industrial assets typically operate in.

Beyond profile, surface prep removes mill scale, rust, oil, and other contaminants that would sit between the coating and the steel and cause early failure. Get this step right, and the coating has a real chance of performing as specified. 

What AS 1627 actually means

AS 1627 is the Australian Standard for preparation of steel substrates before the application of paints and related products. It defines the cleanliness grades that blasted surfaces should meet, and gives a common language to specify and verify the quality of the work.

The grades most commonly used in industrial work are:

• Sa 2 (Commercial blast cleaning): The surface is free from visible oil, grease, dirt, and most rust and contaminants. Some residual staining is acceptable. Used for lower-risk applications.

• Sa 2.5 (Near white metal blast cleaning): Slight traces of staining may remain but the surface is largely free from all contaminants. This is the standard required by most paint manufacturers for industrial coating work. It's the grade Masterblasters work to on the majority of jobs.

• Sa 3 (White metal blast cleaning to visually clean steel): The surface is completely free from all contaminants and has a uniform metallic colour. Required for the most demanding environments and high-performance coating systems.

What happens when prep is cut short:

The consequences don't always show up immediately. That is part of what makes inadequate prep so problematic. A job can look perfectly fine on completion and start failing within months as moisture gets under the coating or rust works its way through at a contamination point.

By the time the problem is visible, the coating has often already failed across a wider area than what you can see from the surface. Re-blasting and recoating an asset is expensive and time-consuming and it almost always results in down time, disassembly and logistical costs. 

Doing it again because the first contractor cut corners is even more frustrating.

In the worst cases, coating failure on critical assets creates safety risks and compliance exposure that go well beyond the cost of the repair work itself.

How Masterblasters approaches surface preparation

We have a fully equipped blasting facility and the experience to prepare substrates to the grade required by the specified coating system. Our coating inspector holds AMPP Level 2 accreditation, which means every job is assessed and verified by someone who actually knows what they're looking at.

We document the surface profile and blast grade achieved on every job as part of our quality management reporting. That documentation gives you a clear record that the work was done to the required standard, which matters for compliance, warranty purposes, maintenance records and your own peace of mind.

Surface preparation isn't the part of the job you'll see when it's finished. But it's the part that determines whether everything else holds up.

Want to know more about how we specify and document surface preparation on our jobs? Talk to the Masterblasters team in Toowoomba.