How to Properly Prepare Metal Before Applying Industrial Paint

Proper surface preparation is the single most important step in any industrial painting project. Even the highest-performing industrial coatings, such as Jotun Jotamastic 90, will fail if applied to poorly prepared metal.

In fact, industry studies suggest that over 80% of coating failures are due to inadequate surface preparation.

This guide breaks down how to prepare different metals correctly and why these steps are essential for achieving a long-lasting, protective finish.

Why Surface Preparation Makes or Breaks Your Coating

Metal surfaces are challenging to coat because of hidden contaminants, rust, and existing finishes.

Skipping or rushing this process compromises adhesion, accelerates corrosion, and shortens your coating’s lifespan.

Some key preparation concerns include:

• Contaminants: Oils, salts, and residues prevent adhesion.

• Rust and mill scale: Corrosion spreads under coatings if not fully removed.

• Surface profile: Coatings need the right “tooth” (roughness) to grip the substrate.

Correct preparation has a positive effect on the cosmetic outcome and also determines how well your coating performs in harsh environments like marine or industrial facilities.

The Essential Steps for Preparing Metal for Industrial Paint

1. Clean and Degrease Thoroughly

Start with a deep clean to remove:

• Oils and greases

• Salt deposits (especially in marine environments)

• Dust, dirt, and chemical residues

Use industrial degreasers or solvent cleaning for best results. In marine applications, begin with a freshwater wash to remove salt before any mechanical preparation.

2. Mechanical Preparation: Choosing the Right Method

The right approach depends on your project and coating system:

• Abrasive Blasting: The industry gold standard, providing a uniform, rough profile. For premium systems like Jotun Jotamastic 90 Aluminium, blasting to SA 2.5 (near-white metal) is recommended.

• Power Tool Cleaning: Ideal for maintenance work or where blasting isn’t practical, using grinders or wire brushes to remove loose coatings and rust.

• Hand Tool Cleaning: Suitable for small touch-ups, though less effective for long-term protection.

3. Create the Correct Surface Profile

The surface profile (roughness) directly impacts how well a coating adheres.

Coating Type	Recommended Profile
Thin-film (e.g., Jotun Pilot II)	25–50 microns
General industrial applications	50–75 microns
High-build epoxy (e.g., Jotamastic 90)	75–100+ microns

4. Final Cleaning

After blasting or mechanical prep:

• Blow off debris with clean, oil-free compressed air.

• Wipe surfaces with approved solvents.

• Ensure surfaces are completely dry before coating.

5. Apply Primer Quickly

Bare metal oxidises almost immediately, especially in coastal areas like Fremantle. Apply a primer or direct-to-metal product such as Jotun Conseal TU within 4 hours of preparation.

Preparing Different Metal Types

Carbon Steel

• Remove all mill scale and rust.

• Blast to SA 2.5 for maximum protection in aggressive environments.

Aluminium

• Avoid steel abrasives to prevent galvanic corrosion.

• Use non-metallic abrasives to create a light profile.

• Apply aluminium-friendly primers or epoxy systems like Jotamastic 90 Aluminium.

Galvanised Steel

• Use sweep blasting with fine, non-metallic abrasives.

• Avoid aggressive prep that strips the zinc coating.

• Select primers designed for galvanised surfaces.

Common Preparation Mistakes to Avoid

• Skipping degreasing – invisible films block adhesion.

• Incorrect profile – too smooth a surface weakens mechanical grip.

• Delayed priming – freshly prepared metal oxidises within hours.

• Prepping in poor conditions – high humidity or dew points cause flash rust.

• Using the wrong abrasives – different substrates require different methods.

Seacraft Paints can assist you with protecting structural steel, marine equipment, or industrial assets, and more. Visit our South Fremantle store or call (08) 9332 8141 to discuss your project. Our range of premium Jotun, Altex, and Norglass coatings is engineered to perform when applied to properly prepared surfaces.