2nd September 2024
When it comes to metal protection, two prevalent methods stand out: Hot Zinc Spray (HZS) and Hot Dipped Galvanizing (HDG).
Both have their unique advantages and applications, but understanding why one might be preferred over the other requires a closer look at their histories, processes, and specific benefits and drawbacks.
At NSP Coatings, we exclusively offer Hot Zinc Spray because we believe it provides superior coverage for subsequent top coats.
Here’s a comprehensive overview to help you understand Why Use Hot Zinc Spray Over Hot Dipped Galvanizing?
The History of Zinc Coating
Zinc coating has been used to protect metal surfaces for nearly 200 years. The process was first introduced in the early 19th century, with the aim of combating the detrimental effects of corrosion. Corrosion not only weakens metal structures but also affects their appearance and longevity.
Hot Dipped Galvanizing: This process dates back to 1836, when French engineer Stanislas Sorel patented the technique. It involves immersing steel or iron in a bath of molten zinc, which forms a thick, protective layer over the metal. The method gained widespread acceptance for its effectiveness in preventing rust and corrosion.
Hot Zinc Spray: Also known as thermal zinc spraying, this process emerged in the early 20th century as a more flexible alternative to HDG. It involves melting zinc and spraying it onto the metal surface, providing a strong, protective coating without the need for immersion in molten zinc.
How the Processes Work
Hot Dipped Galvanizing:
- Surface Preparation: The metal is cleaned thoroughly to remove any rust, oil, or contaminants, usually by shot blasting.
- Fluxing: A flux solution is applied to remove any remaining oxides and ensure proper bonding of the zinc.
- Galvanizing: The metal is dipped into a bath of molten zinc, typically heated to around 450°C (842°F). The zinc reacts with the iron in the steel to form a series of zinc-iron alloy layers.
- Cooling: The metal is then removed from the bath and allowed to cool, forming a thick, durable coating.
- Post-Spray Treatments: The item will often need fettling before any paint is applied for a smooth top coat finish.
Why Use Hot Zinc Spray Over Hot Dipped Galvanizing?
- Surface Preparation: Similar to HDG, the metal surface is thoroughly cleaned, often using shot blasting to ensure optimal adhesion.
- Spraying: Zinc wire is fed through a thermal spray gun, where it is melted and sprayed onto the metal surface. The zinc particles solidify upon contact, forming a strong, protective layer.
- Post-Spray Treatments: The sprayed surface can have its top coat applied without the need for fettling.
Pros and Cons of Each Method
Hot Dipped Galvanizing:
Pros:
- Durability: Provides a thick, robust coating that offers excellent protection against corrosion and mechanical damage.
- Complete Coverage: Ensures all surfaces, including edges and corners, are fully coated.
- Long-Lasting: The zinc-iron alloy layers provide long-term protection, often lasting several decades.
Cons:
- Size Limitations: Large or complex structures may be difficult to immerse in the molten zinc bath.
- Heat Effects: The high temperatures involved can cause warping or distortion of thinner metal sections.
- Surface Finish: Can result in a rough or uneven surface, which may not be suitable for all applications.
Hot Zinc Spray:
Pros:
- Flexibility: Suitable for large or complex structures that cannot be easily dipped.
- Controlled Thickness: Allows for precise control over the thickness of the zinc coating.
- Surface Finish: Provides a smoother, more uniform surface, ideal for subsequent top coats.
- Minimal Heat Effects: Lower application temperatures reduce the risk of warping or distortion.
Cons:
- Initial Cost: Equipment and setup costs can be higher compared to HDG.
- Skill Requirement: Requires skilled operators to ensure consistent and high-quality application.
Why NSP Coatings Chooses Hot Zinc Spray
At NSP Coatings, we exclusively offer Hot Zinc Spray because we believe it delivers superior coverage and protection for the next top coat. Here’s why:
- Enhanced Coverage: The flexibility of HZS allows us to coat large and complex structures that might be challenging to dip in a molten zinc bath. This ensures comprehensive protection without the limitations posed by the size or shape of the item.
- Superior Surface Finish: The smoother, more uniform surface provided by HZS is ideal for applying subsequent top coats. This results in a more aesthetically pleasing and durable final product.
- Controlled Application: With HZS, we can precisely control the thickness of the zinc coating, tailoring it to the specific requirements of each project. This level of control is crucial for ensuring optimal protection and performance.
- Reduced Risk of Distortion: The lower application temperatures used in HZS minimise the risk of warping or distorting thinner metal sections, preserving the structural integrity of the item.
- Environmentally Friendly: HZS produces less waste and uses less energy compared to HDG, making it a more environmentally sustainable option.
Conclusion
While both Hot Zinc Spray and Hot Dipped Galvanizing offer significant benefits for protecting metal from corrosion, the choice between the two depends on the specific needs of the project. At NSP Coatings, we advocate for Hot Zinc Spray due to its superior coverage, controlled application, and better surface finish, which collectively provide a more reliable and aesthetically pleasing result for subsequent top coats.
If you’re interested in learning more about how Hot Zinc Spray can benefit your next project, or if you have any questions about our services, don’t hesitate to contact us. We’re here to ensure your metal structures receive the best possible protection, enhancing their longevity and performance.
