Choosing the Right Powder Coating Specification: A Guide for Engineers & Architects

When you’re designing or managing a project, powder coating might seem like just another finish on the specification sheet. But choosing the right specification is critical to ensure your structure, façade, or component performs as expected in the real world. Powder coating is more than a splash of colour – it provides durability, corrosion resistance, and aesthetic value, but only when matched properly to the application.

This guide will walk you through the essentials of powder coating specifications, the pitfalls of incorrect choices, and how to align your project requirements with the right coating system.

Why Powder Coating Specifications Matter

Powder coating has become the finish of choice for architects, engineers, and manufacturers because it offers:

• Durability – hard-wearing surfaces resistant to scratches, chips, and abrasion.
• Corrosion protection – when applied correctly with proper pretreatment.
• UV stability – coatings can resist colour fade and chalking, critical for outdoor projects.
• Sustainability – powder coating is solvent-free with minimal waste.

The challenge lies in the fact that not all powder coatings are the same. Using the wrong chemistry, skipping pretreatment steps, or specifying insufficient film thickness can shorten the lifespan of a project by years.

Step 1: Understand the Chemistry

Different powder coating chemistries are suited to different environments and applications. Some of the most common include:

Epoxy

• Best for: indoor applications, industrial parts, electrical insulation.
• Strengths: excellent chemical and corrosion resistance, smooth finish.
• Limitations: poor UV resistance – chalks and fades quickly in sunlight.

Polyester

• Best for: outdoor environments, architectural façades, furniture, automotive.
• Strengths: good UV resistance, excellent mechanical properties.
• Limitations: less chemical resistant than epoxy.

Epoxy-Polyester Hybrid

• Best for: indoor decorative items and office furniture.
• Strengths: balanced cost and performance, smooth finish.
• Limitations: not suitable for outdoor use.

Fluoropolymer (PVDF, FEVE, etc.)

• Best for: extreme environments, high-end architectural applications.
• Strengths: superior UV and weather resistance, long-term colour stability.
• Limitations: higher cost, requires expert application.

Tip for specifiers: Start by matching the coating chemistry to the expected exposure environment. For example, specifying epoxy for outdoor façades is a recipe for premature failure.

Step 2: Prioritise Pretreatment

A great coating is only as good as the surface it adheres to. Pretreatment is often overlooked but plays the biggest role in corrosion protection.

• Mechanical preparation: blasting or sanding removes rust and scales.
• Chemical pretreatment: phosphating or chromating creates a conversion layer that promotes adhesion.
• Chromate-free alternatives: widely adopted due to environmental standards, such as zirconium-based coatings.

For coastal or industrial areas with high salt and pollutant exposure, a robust pretreatment system is non-negotiable. Engineers should always ask coating suppliers what pretreatment process is being used before approving a specification.

Step 3: Determine Film Thickness

Film thickness, usually measured in microns, impacts durability and appearance.

• Too thin: inadequate coverage, reduced corrosion protection.
• Too thick: risk of chipping, orange peel effect, and curing issues.

Typical architectural powder coatings range from 60–100 microns. In highly corrosive environments (e.g. beachfront developments), a duplex system (galvanising + powder coat) or higher build coatings may be required.

Step 4: Match to Environmental Standards

In Australia, powder coatings for architectural applications are often specified under standards such as:

• AS 4506 – Metal finishing: thermoset powder coatings.
• AS 3715 – Metal finishing: requirements for application of thermoset powder coatings to aluminium used in architectural applications.

Additionally, products certified under recognised schemes provide confidence that coatings meet rigorous durability requirements:

• APAS (Australian Paint Approval Scheme) – An Australian certification managed by CSIRO that ensures coatings comply with national standards.
• Qualicoat – An internationally recognised certification that sets high global standards for powder-coated aluminium in architectural applications. Many Australian coaters follow Qualicoat to demonstrate compliance with international quality benchmarks, particularly for high-end or export projects.

By aligning specifications with these standards, you protect the project from premature warranty claims and ensure compliance with building codes.

Step 5: Consider Aesthetics and Design Intent

While performance is critical, aesthetics can’t be ignored. Powder coatings come in a wide range of finishes – matte, gloss, satin, textured, metallic, pearlescent – and an almost limitless palette of colours.

However, not every finish performs equally in harsh conditions. High-gloss finishes may highlight surface imperfections, and metallics may weather differently than solid colours. Collaborating with the coating applicator during the design phase ensures the finish you envision is practical for long-term exposure.

Common Pitfalls in Powder Coating Specifications

Even experienced specifiers can run into trouble. Some of the most common mistakes include:

1. Specifying for price, not performance – choosing a cheaper polyester when a fluoropolymer is required.
2. Overlooking pretreatment – assuming all applicators use the same process.
3. Ignoring the environment – indoor-grade finishes specified for outdoor marine projects.
4. Not checking warranty conditions – coatings may only last as long as they’re maintained according to manufacturer guidelines.

Each of these mistakes can result in premature corrosion, costly rectification, and reputational damage.

A Practical Specification Checklist

Here’s a quick checklist engineers and architects can use when finalising a powder coating specification:

• What is the environment (indoor, outdoor, coastal, industrial)?
• What powder coating chemistry matches this environment?
• What pretreatment process will be applied?
• Is the specified film thickness adequate?
• Does the product meet AS, APAS, or Qualicoat standards?
• What warranty is available, and what are the conditions?
• Does the selected finish align with the design intent and expected lifespan?

Case Study: Getting the Specification Right

A recent commercial façade project in Brisbane required a durable finish for aluminium cladding panels within 2 km of the coastline. The architect initially specified a polyester system. Superior Coaters reviewed the project environment and recommended upgrading to a fluoropolymer system with zirconium-based pretreatment.

The result was a 20-year warranty, improved colour stability, and peace of mind for both the architect and the developer. Had the original specification been used, the façade may have shown chalking and fading within just a few years.

Final Thoughts

The success of a project doesn’t just depend on the design – it depends on the details. Powder coating is one of those details that can either elevate a project or cause long-term headaches. By understanding powder coating chemistries, prioritising pretreatment, and aligning specifications with standards, engineers and architects can ensure their work stands the test of time.

At Superior Coaters, we’ve seen first-hand how the right specification makes all the difference. If you’re unsure about which system to choose, our team can review your project requirements and provide expert recommendations tailored to your environment.