Metal Protection for Playgrounds: Galvanizing and Powder Coating

Steel on children's playgrounds is permanently exposed to outdoor conditions. Unlike structural steel enclosed within a building envelope, playground posts, structures and fasteners are continuously exposed to rain, moisture, direct UV radiation, freeze-thaw cycles, and in coastal areas or winter conditions with de-icing salt, exposure to salt as well. None of these conditions is occasional. They form the equipment's working environment for its entire service life, and steel responds to that environment whether protection was specified for it or not.

Unprotected or under-protected steel corrodes. Corrosion is not just a cosmetic issue. It progressively reduces the effective thickness and strength of a structural element, and it tends to concentrate exactly where it matters most: welds, cut edges, fixing holes and the base of posts, where they meet the ground or foundation. These points are also often the most heavily loaded locations on a piece of play equipment. For an architect or the person preparing a technical specification, metal protection therefore belongs in the same conversation as structural calculations and fall-height compliance, not a decision left until the end as a finishing detail. It is first and foremost a question of durability, and only secondarily one of appearance, even though most non-specialists start thinking about the topic from appearance first.

Choosing the right combination of galvanizing, powder coating or a duplex system is one of the highest-consequence decisions in a playground equipment specification, precisely because the consequences of getting it wrong show up slowly, are structural in nature, and are expensive to correct later. This article explains each process separately, compares them, and sets out questions worth asking a manufacturer, regardless of how the equipment is produced. For a broader look at how metal choices sit alongside other playground materials, see Best Materials for Outdoor Playgrounds.

Hot-dip galvanizing is the process of applying a layer of zinc to steel as a dedicated corrosion-protection layer, applied before any decorative finish. It is one of the oldest and most reliable methods of protecting structural steel used outdoors, and it remains a standard base layer of corrosion protection for playground steel that needs to stay functional for years in an uncontrolled outdoor environment.

How the process works

Fabricated steel elements are first cleaned and prepared, then fully immersed in a bath of molten zinc, typically at a temperature of around 450 degrees Celsius. The zinc reacts with the iron at the steel's surface to form a series of zinc-iron alloy layers, topped with a final layer of pure zinc. This is a metallurgical bond, not a surface film simply sitting on top of the steel. Because the entire element is immersed, the zinc coats every exposed surface, including the inner walls of hollow profiles, the inside of drilled holes, cut edges and welded joints, not just the outer surfaces that spraying or brush application would reach.

This full-immersion characteristic is what sets galvanizing apart from almost every other coating method, and it is the key reason it performs so well on complex fabricated shapes such as playground posts, connectors and tube assemblies.

What it protects against

The primary role of galvanizing is to prevent the spread of corrosion, the process in which rust spreads outward from a small vulnerable point until it compromises a much larger area of otherwise sound steel. Cut edges and welds are usually the most vulnerable points on any steel element, since fabrication processes can damage or bypass a coating that was originally applied only to the flat, unprocessed material. An element that is galvanized after fabrication, rather than shaped from already-galvanized sheet, carries protection into exactly those most vulnerable areas.

Zinc also protects steel electrochemically. If the coating is scratched or damaged, the surrounding zinc corrodes preferentially and continues to protect the small exposed area of steel, rather than that exposed area immediately beginning to rust on its own. This self-protecting behaviour at points of minor damage is one of the practical reasons galvanizing is considered a reliable base layer beneath other finishes.

Powder coating is a decorative and protective finish applied as a dry pigment, then baked into a hard, continuous layer. It is the coating that gives most playground equipment its colour, texture and finished appearance, and it plays a real role in surface durability as well, not just aesthetics.

How the process works

Dry powder, typically a mix of resin and pigment, is applied to a prepared steel surface using electrostatic spraying. An electrical charge on the powder particles allows them to adhere evenly to the earthed metal element, including corners and recesses that liquid paint could run off. The coated element is then heated in a curing oven, where the powder melts and chemically cross-links into a continuous, durable film firmly bonded to the surface it was applied to.

What it adds

Correctly applied, powder coating gives playground steel a wide range of colours, and modern powder formulations are designed to hold colour under prolonged UV exposure without the fading or chalking that affects some liquid paints over time. The cured coating is smooth, resistant to chipping and abrasion under normal use, and easy to keep clean. Applied to a suitable, well-prepared surface, it contributes meaningfully to both the appearance and the function of equipment over years of outdoor use, and represents a legitimate part of an overall protection system, not merely a cosmetic layer.

Limitations when used on its own

The limitation of powder coating lies in what it is applied to and how it is applied, not in the coating chemistry itself. A powder coating applied directly to bare or insufficiently prepared steel, without proper surface preparation or a corrosion-resistant layer underneath, offers significantly less protection than the same coating applied over galvanized steel. Powder coating is a surface film. It does not form the metallurgical bond that galvanizing does, and it does not reach the inner surfaces of hollow profiles the way full immersion does.

More importantly, any damage to the powder coating, whether a scratch during assembly, an impact during use, or a poorly finished cut edge, directly exposes bare steel to moisture and air, with nothing underneath to slow corrosion once it starts. This is the key reason powder coating on its own is generally regarded as a finish, rather than a complete corrosion-protection strategy for steel that spends its entire service life outdoors.

A duplex system applies both processes to the same element, first hot-dip galvanizing, then powder coating over the galvanized surface. This combination is most commonly specified for outdoor playground steel where both long-term corrosion resistance and a specific appearance are required.

Why this combination is common on outdoor playground equipment

The logic of a duplex system is straightforward: each process does the job it is best suited for. The zinc layer handles corrosion resistance, including at cut edges, welds and internal surfaces, and continues to protect the steel electrochemically even after the powder coating is later damaged. The powder coating provides colour, UV stability and a smooth, even surface appearance, along with an additional physical barrier above the zinc. Together, the two layers compensate for each other's limitations. A scratch that breaks through the powder coating still lands on protected, galvanized steel rather than bare metal, which is a very different outcome from a scratch through powder coating applied directly to unprotected steel.

This is why a duplex system is a standard recommendation, not an unusual upgrade, for playground equipment that needs to perform reliably in an uncontrolled outdoor environment over many years, particularly in climates with high humidity, heavy rainfall or salt exposure.

Where surface preparation and adhesion between layers are critical

The effectiveness of a duplex system depends on how well the two layers work together, not simply on the fact that both were applied. Galvanized steel has a different surface profile and chemical properties from bare steel, so it typically requires specific pre-treatment, sometimes surface roughening or a compatible primer, so that the powder coating has a surface it can properly bond to. Poor adhesion between the zinc layer and the powder coating can lead to peeling or blistering, which has nothing to do with the zinc's corrosion resistance on its own, but which does undermine the appearance and, over time, the protective value of the entire system.

For the person preparing a technical specification, this means a duplex protection note on a data sheet is only as reliable as the surface preparation and process control behind it. Two elements that are both described as "galvanized and powder coated" can perform very differently in practice, depending on how carefully the transition between layers was managed.

Material selection also interacts with a playground's other components. To compare metal against alternative material systems such as HPL and compact panels, see HPL and Compact Panels for Playground Materials.

How long any of these protection systems performs in practice depends on a number of factors working together, not just on the name of the process. One is coating thickness: a thicker, properly controlled layer of zinc or powder generally provides longer-lasting protection than a thin layer, and thickness should be confirmed through technical documentation, not assumed. Surface preparation quality matters just as much. Steel that is properly cleaned, degreased and profiled before a coating is applied gives each subsequent layer a far better chance of adhering correctly and performing as expected, while inadequate preparation can undermine even a good-quality coating material.

Process control during application, consistent temperatures, correct curing time and careful handling of elements between coating stages, affects the uniformity and integrity of the finished coating. Local climate is an additional variable that specification writers should account for directly: locations near the coast or exposed to de-icing salt face significantly more demanding conditions than continental, temperate locations, so protection systems that perform well in one environment may need a more robust specification in another. Finally, regular maintenance, from routine inspections to prompt response to any damage, has a real role in how long a protection system continues to perform after installation.

This article deliberately does not state specific lifespan figures or warranty periods for coating systems, since actual performance is the result of the variables described above on a given project, not a fixed number that holds universally. For a broader look at how material choice, protection systems and design decisions together determine the overall lifespan of playground equipment, see Factors Affecting Playground Equipment Lifespan.

A specification is only as good as the documentation behind it. These questions belong at the stage of preparing a project's technical specification, where general understanding of materials is turned into documented, verifiable requirements. For guidance on including this documentation in a formal specification, see Playground Technical Specification. When reviewing a manufacturer's proposal, the following questions apply regardless of who carries out the coating process:

REDOX specifies metal protection suited to the climate, structural requirements and intended use of each individual project. Project teams can request the specific protection process and the technical documentation behind the proposal for their site.

Send us details of the metal elements and site conditions for your project for an expert conversation about the right approach to protection.