Galvanized vs. Thermoplastic Coatings: Choosing the Right Protection for Steel

When it comes to protecting steel structures and components, two of the best coating methods are galvanization and thermoplastic powder coating. Each has distinct advantages and specific applications where it excels. It is important to note, that thermoplastic powder coating is distinctly different than the common thermoset powder coating that you'll find on most gym equipment, trailers, and other steel products.

Galvanization, a process that applies a layer of zinc to steel, has long been a trusted method for corrosion protection. However, its sacrificial nature means that over time, the protective coating can wear away, leaving the steel vulnerable.

On the other hand, thermoplastic powder coating is a durable, aesthetically versatile, and environmentally friendly alternative that offers a wide range of benefits, including superior resistance to weather, impact, and even thermal loading in direct sunlight.

In this article, we'll compare these two coatings, examine their performance in different environments, and discuss why thermoplastic powder coatings are the best choice for outdoor play equipment and outdoor gym equipment.

Understanding Galvanization: Sacrificial but Effective

How Galvanization Works

Galvanization involves coating steel or iron with zinc to protect it from corrosion. The most common method, hot-dip galvanization, submerges the metal in molten zinc, forming a protective layer that bonds to the surface. This layer acts as a sacrificial barrier. If the zinc coating is damaged, it corrodes first, preserving the steel underneath.

Other forms of galvanization include:

• Electro-galvanization, which applies a thinner zinc layer via electroplating.
• Mechanical galvanization, which uses mechanical means to bond zinc powder to steel.

Advantages of Galvanization

• Good Corrosion Protection. Galvanized coatings provide strong resistance against moisture, oxidation, and other environmental elements.
• Sacrificial Nature. Even when the surface is scratched, the surrounding zinc will corrode before the steel does.
• Can Reach Inaccessible Areas. Unlike traditional powder coating, hot-dip galvanization can coat inside crevices and hollow structures.
• Longevity in Mild Environments. In rural or low-pollution environments, galvanized steel can last several decades.

Limitations of Galvanization

• Sacrificial Degradation. Over time, the zinc layer deteriorates, and once it wears away, the steel underneath is left unprotected.
• Limited Aesthetic Appeal. Galvanized coatings have a dull, metallic finish that cannot be customized with bright colors.
• Not as Resistant to Chemicals and Abrasion. While effective against general corrosion, galvanized coatings may degrade faster in acidic or high-salinity environments.
• Heat Retention. Galvanized surfaces tend to absorb and retain heat, which may not be ideal for applications in high-temperature or sun-exposed environments.

Thermoplastic Powder Coating: A High-Performance Alternative

How Thermoplastic Powder Coating Works

Thermoplastic powder coating is a process in which a plastic-based powder is melted onto a metal surface, forming a thick, durable, and flexible protective layer. Unlike thermoset powders, which cure irreversibly through a chemical process, thermoplastics can be reheated and reformed if needed.

Popular thermoplastic coatings include:

• Polyethylene (PE). A cost-effective choice with good resistance to impact and weather.
• Polyvinyl chloride (PVC). Excellent for chemical resistance and flexibility.
• Polyamide (Nylon). Superior wear resistance, ideal for high-friction applications.
• Polyolefin. Well-suited for UV resistance and outdoor exposure.

Advantages of Thermoplastic Powder Coating

• Exceptional Durability. Unlike galvanization, thermoplastic coatings do not rely on sacrificial protection. They offer superior impact resistance, chemical resistance, and weatherproofing.
• Bright, Vibrant Colors. Available in a variety of shades, thermoplastic coatings allow for aesthetic customization, making them ideal for architectural, recreational, and industrial applications.
• Superior UV and Thermal Resistance. Certain thermoplastic formulations help reduce heat absorption, keeping surfaces cooler in direct sunlight. This is particularly beneficial for outdoor equipment, playground structures, and exposed steel surfaces.
• Flexibility and Crack Resistance. Unlike brittle coatings, thermoplastics can flex and absorb mechanical stress without cracking or chipping.
• Non-Toxic and Environmentally Friendly. Unlike some traditional coatings, thermoplastic powder coatings contain no volatile organic compounds (VOCs), making them safer for workers and the environment.

Limitations of Thermoplastic Powder Coating

• Application Limitations. Unlike hot-dip galvanization, powder coating requires an electrostatic application process and heat curing, making it challenging to coat internal or recessed areas.
• Higher Initial Cost. While thermoplastic coatings provide long-term savings through durability and low maintenance, the upfront costs of application equipment and labor can be higher than galvanization.
• Not Ideal for High-Temperature Environments. While resistant to heat, some thermoplastic coatings may soften or degrade under prolonged exposure to extreme temperatures.

Comparing Performance: Galvanization vs. Thermoplastic Powder Coating

Which Coating is Best for Your Application?

When to Choose Galvanization

• If the steel structure has areas that cannot be accessed for coating, such as hollow tubes or internal sections.
• If sacrificial corrosion protection is acceptable and longevity is sufficient for the intended environment.
• If the steel will be used in general outdoor applications where aesthetics and extreme wear resistance are not primary concerns.

When to Choose Thermoplastic Powder Coating

• If vibrant colors and a smooth finish are important for aesthetics, such as in architectural or recreational settings.
• If long-term durability and low maintenance are priorities, especially in high-traffic or high-impact environments.
• If the coating needs to resist chemical exposure, abrasion, and UV damage better than galvanized coatings.
• If heat reduction in direct sunlight is a concern, making thermoplastics ideal for places where people touch the equipment, like playgrounds, fences, and handrails.

Both galvanization and thermoplastic powder coating offer strong protective benefits for steel, but their applications differ significantly. While galvanization provides reliable sacrificial corrosion protection, it lacks the aesthetic appeal, flexibility, and long-term resilience of thermoplastic coatings.

Thermoplastic powder coatings offer a vibrant, durable, and environmentally friendly alternative, making them an excellent choice for applications requiring superior impact resistance, color variety, and heat reflection.

Choosing between the two depends on the specific environmental and functional requirements of your project. If aesthetics, durability, and long-term performance are your priorities, thermoplastic powder coating is the way to go. If you need corrosion protection for inaccessible areas, galvanization might still be your best bet.

By understanding the strengths and limitations of each method, you can make an informed decision to ensure your steel structures and components remain protected, functional, and visually appealing for years to come.

Naomi Leeman

Naomi is co-founder and COO here at SwingSesh. With years of experience in landscape architecture and urban design, Naomi enjoys helping people make their spaces functional and beautiful! When her husband Brad had the idea to combine a home gym with a backyard playground, she was on board immediately and hasn't looked back since!