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    February 9, 2022

    Compare the Methods: Cold Galvanizing Spray vs. Cold Galvanizing Brush

    You've spent a lot of time and money planning and implementing strategies for your project's success. Whether fabricating steel for cell towers or constructing a new water facility, defending against corrosion is paramount in protecting your investment.

    Cold galvanizing compounds in the form of zinc-rich coatings are the industry-leading solution for corrosion prevention. A cold galvanizing compound is a high-quality, easily accessible solution for corrosion prevention. With a significant lifespan in the right conditions, it is perfect for touch-ups or full-scale project application.

    Explore how the different application methods of cold galvanizing compounds can transform your projects.

    What is a cold galvanizing compound?

    Cold galvanizing compounds are paint-like coatings that are applied to iron and steel surfaces to prevent corrosion. They can also be referred to as zinc-rich coatings. A cold galvanizing compound has the characteristics of a paint, but it's not a paint. The biggest difference between paint and cold galvanizing compounds exists in the percentage of zinc present in the corrosion-prevention film coating. However, there are a lot more factors that make a cold galvanizing compound unique, factors we discuss in more detail in our blog, What is a Cold Galvanizing Compound? 

    ZRC Worldwide developed the technology behind zinc-rich coatings and their application as corrosion-prevention solutions. Matt Steele of ZRC Worldwide provides an overview of zinc-rich coatings:

    "Cold galvanizing compounds are a very high-end solution that set the gold standard of corrosion protection for iron and steel. If you want to protect a piece of steel from corrosion it's easy to use a cold galvanizing product because it's applied like a paint"

    Cold Galvanizing Versus Hot-Dip Galvanizing

    You may have heard about hot-dip galvanizing, another process for protecting metal surfaces from corrosion. While hot-dip galvanizing has its uses, cold galvanizing compounds are a superior choice.

    • Hot-dip galvanizing needs to be applied in a controlled setting, like a manufacturing plant.
    • Cold galvanizing compounds can be applied, like a paint, out of a can and on-site.

    One major benefit of cold galvanizing compounds as compared to hot-dip is proximity — you can apply cold galvanized compounds on-site instead of instead of having to outsource the corrosion prevention process.


    Application methods and their benefits

    Once applied and dried, zinc-rich coatings are designed to perform to the same industry standard of corrosion prevention whether sprayed-on or applied by brush. Even though they perform the same once applied, there are still factors to consider when choosing an application method. 


    When applying cold galvanizing compounds in the form of zinc-rich coatings to iron or steel by brush, applying the film coating onto the surface of the material like a paint is a best practice. This ensures you achieve a strong bond between the zinc and the metal that is being protected.

    Be sure to cover the intended surface evenly. You will need to apply two coats in order to replicate the performance of hot-dip galvanizing. Professional coatings applicators actually measure the dried film thickness of the zinc-rich coating to ensure that an adequate film thickness exists.

    Main benefit: Brush-on applications will create a better interface between the product and the protected surface than a spray-on application will, Brushing mashes the zinc onto the surface and creates better contact between the zinc and steel.


    Aerosol vs. Compressor

    The spray-on application of cold galvanized compounds can be administered in aerosol form or by use of a compressor or airless spray techniques. Like the brush-on application method, be sure to cover the intended surface evenly with the zinc-rich coating, and apply two coats to achieve the same corrosion protection as hot-dip galvanizing.

    Touching up an existing corrosion protection solution? Aerosol is the best product for your project. Much like a can of spray paint, you can shake up your can of cold galvanized compound and apply it directly to any blemished areas of coating. Aerosol will also work well for new projects that focus on preventing corrosion on smaller surface areas.

    ZRC's cold galvanizing compound in aerosol yields the same superior performance as the brush-on type. ZRC simply adds propellants and other ingredients so it sprays easily and evenly out of a aerosol can. ZRC Worldwide's aerosol application method is low in VOC and yields a consistent dry film thickness not found in low cost solutions. This does not change the performance of the product.

    Dealing with a larger project that requires coating a large surface area? Consider using a compressor to apply a cold galvanizing compound to your target iron or steel material. An airless spray system may be a better choice if your project involves building construction or large-scale steel fabrication.

    Main benefit: Spray-on applications easily cover more surface area in less time.

    Are there any industry standards or protocols that dictate when to use one application or the other?

    A lot of projects will specify that a corrosion prevention product must be used in accordance with a standard method of protection, but most architects and structural engineers will not specify the method of application. This means you can select your prefered method based on your wants and needs.

    There are two standard classifications of zinc percentages typically recognized for cold galvanizing compounds:

    • 65-69%
    • >92%
    • (per ASTM A780)

    The Association for Materials Protection and Performance (AMPP), formerly the Society for Protective Coatings (SSPC), aims to regulate the industry standards for features and performance of cold galvanizing compounds. They offer a set of many standardizations, the most common of which for cold galvanized compounds is called SSPC Paint 20. You can learn more about AAMP standards, certification, and training on their website.

    Common misconceptions about the different ways to apply cold galvanizing compounds

    There are a lot of things that get misconstrued with cold galvanizing compounds.

    The biggest one? People think a cold galvanizing compound is a normal paint that can be applied as such. Google will probably show you pictures of corrosion solutions that come in cans looking similar to those containing paint products. But since cold galvanizing products are not the paints they are so often mistaken for, they have to be applied properly to work as intended.

    Other misconceptions include:

    • Does it need to be cold? No —the terminology "cold galvanized" does not mean that it needs to be applied in a cold environment. A normal, temperate one will do just fine.
      • The language comes from the product's creation in the 1950s as an alternative to its molten-zinc counterpart and has followed it to present day.
    • Is it just for small areas? No — cold galvanizing compounds can be used for the overall galvanization of entire structures and not just for touch-ups.
    • Should I be concerned about quality? Not with the right products. Many people have had poor experience with a zinc-poor product masquerading as a cold galvanized compound. As the creators of zinc-coating technology, ZRC Worldwide has upheld the highest product quality in the industry for over 50 years.

    Choosing the right cold galvanizing product

    There are many products that service the varying needs of the corrosion prevention industry. Imitation is flattering, but the proof is in the paint. ZRC Worldwide created zinc coating technology as a hot-dip alternative to combat corrosion and has been a worldwide leader in the space for almost 70 years.

    Whether touching up an existing project or completing a full-sized job from scratch, our team will ensure you get the right product and the correct application method for your needs. Visit our store.

    Galvanic Corrosion Prevention Guide Everything you need to know about galvanic corrosion prevention