When it comes to protecting steel from rust and corrosion, cold galvanizing is one of the most effective and trusted methods available — but that doesn’t mean it’s always well understood. Whether you're an engineer writing a spec, a contractor tackling surface prep, a facility manager weighing long-term maintenance strategies, or a homeowner looking to protect your outdoor furniture, you likely have questions about how cold galvanizing compounds work, when to use them, and how they compare to other corrosion protection solutions.
At ZRC, we’ve been fielding these questions for decades. In this blog, we’re answering the most common ones to help you make confident, informed decisions about corrosion prevention. Let’s dive into the FAQs.
Both cold galvanizing and hot-dip galvanizing are methods used to protect steel and iron from corrosion by applying a zinc-based coating. That’s where the similarities end; how they’re applied and perform differs significantly.
Hot-dip galvanizing involves immersing steel into a bath of molten zinc, creating a thick, metallurgically bonded coating that offers durable, long-term protection. This method is typically performed at a galvanizing facility and is best suited for newly fabricated steel components before they’re installed. It creates a robust layer ideal for high-exposure environments, but once a part is galvanized this way, any cutting, drilling, or welding will compromise the coating and require touch-up.
Cold galvanizing, on the other hand, refers to the application of a high-zinc-content coating (like ZRC's) using a brush, roller, or spray — just like paint. It offers true galvanic protection by using zinc as the sacrificial metal, similar to hot-dip, but with the flexibility of field application. Cold galvanizing is ideal for touch-ups, repairs, weld seams, and maintenance work on-site. It can also be specified as the primary corrosion protection system when hot-dip isn’t feasible due to size, location, or project constraints.
While both offer zinc-based protection, cold galvanizing provides greater convenience, control, and versatility — especially for existing structures and ongoing maintenance needs. And when formulated to meet or exceed industry standards, as ZRC’s products do, it’s a reliable solution with proven performance in the harshest environments.
No, you can't apply cold galvanizing over existing rust or degraded paint. Cold galvanizing paint requires direct contact with clean, bare metal to adhere properly and protect against corrosion effectively. If rust or old paint is left on the surface, the coating won't bond well, which can lead to flaking, peeling, and premature failure.
Surface preparation is key to ensuring proper adhesion and maximizing the life expectancy of the coating. Use a wire brush, sandblaster, or grinder to remove all loose rust, scale, and paint. The cleaner and smoother your surface, the better the cold galvanizing compound will stick — and the longer it will last.
Remember: good prep = longer protection.
When it comes to the longevity of cold galvanizing compounds, it's important to understand that there is no definitive lifespan. Several factors influence the effectiveness and durability of the protection offered by these compounds. Key considerations include the environment in which the product is used, the degree of surface preparation prior to application, the film thickness of the specific ZRC product chosen, and the applicator's proficiency in applying the product.
While we can't provide a firm answer regarding the exact duration of protection, we can confidently say that ZRC's cold galvanizing compounds offer a level of protection equivalent to G60 hot-dipped galvanized coatings. This means that with proper application and consideration of environmental factors, you can expect robust corrosion resistance that stands the test of time.
Cold galvanizing compounds are primarily designed for use on steel and other ferrous metals. They provide excellent corrosion protection by creating a zinc-rich barrier. However, they are not suitable for non-metal surfaces or materials that do not have ferrous properties.
If you're considering using cold galvanizing compounds on materials other than steel, such as aluminum or galvanized surfaces, it's important to note that while some products may adhere, the performance and corrosion protection may not be as effective. Cold galvanizing compounds are not recommended for non-metal surfaces, as they require a metal substrate to bond properly and provide the intended protective qualities.
Yes, cold galvanizing compounds meet industry and government standards for corrosion protection. ZRC products conform to several important specifications, including ASTM 8780, which ensures quality and performance in corrosion resistance. Additionally, our products are certified under the following standards:
These certifications highlight our commitment to providing reliable and effective corrosion protection solutions.
In the majority of circumstances, a topcoat is not needed over a cold galvanizing compound. The inherent properties of the cold galvanizing compound provide effective corrosion protection on their own. However, we recommend applying a topcoat if the surface is exposed to extremely corrosive environments, particularly when the pH level is between 6.5 and 10.5. In such cases, a topcoat can offer additional protection and enhance the longevity of the coating.
Please refer to our guide for top coating specifics.
No, you cannot weld over a surface coated with cold galvanizing compound, as the extreme heat will degrade the coating. The surface temperature rating for cold galvanizing compounds is 350 degrees Fahrenheit, with a tolerance of up to 750 degrees Fahrenheit for intermittent exposure. After welding, you will need to clean the weld points and reapply the ZRC product to ensure continued protection.
For this reason, it's best to perform the welding first and then apply the cold galvanizing compound afterward, as the heat will burn off the protection if you attempt to weld through it.
Yes, cold galvanizing compounds can be environmentally friendly and VOC-compliant. At ZRC, we manufacture products for every type of VOC situation. Our standard products contain 385 grams per liter of VOCs. For those seeking even lower VOC options, we offer ZRC Zero VOC Galvanizing Compound, which you can learn more about on our website.
Combining the best features of organic and inorganic zinc coatings, ZRC® Zero-VOC Galvanizing Compound is water-based and environmentally friendly — and different from other products of its kind with the same quality protection guarantee. It offers the same true cathodic protection as our original ZRC without volatile organic content, solvents, or solvent fumes.
It is also worth noting that preserving the integrity of existing structures rather than replacing them contributes to a lower carbon footprint over their lifetime. Choosing to repair rather than replace is a more environmentally friendly approach.
For more information on which ZRC product has the right VOCs for your use case, please use our product finder.
Yes, ZRC products are easy to apply. Our cold galvanizing compounds can be administered in aerosol form or using a compressor or airless spray techniques. They offer the same superior performance you would find in the brush-on type.
The aerosol spray can be applied directly to the surface, making it particularly user-friendly for touch-ups and smaller projects. 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. It sprays easily and evenly, allowing for a consistent application without extensive equipment.
Our cold galvanizing paint was the original ZRC product and is still the industry standard. It is equivalent in function yet superior in convenience to hot-dip galvanizing. The brush-on application provides excellent control and is ideal for larger projects, ensuring a strong bond between the zinc and the metal surface.
Which application is right for you? Once applied and dried, zinc-rich coatings are designed to perform to the same industry standard of corrosion prevention. This is true whether sprayed on or applied by brush. They perform the same once applied! Both options deliver superior performance, making it straightforward for users to achieve effective corrosion protection with minimal hassle.
No, that is not recommended. Applying a primer before using ZRC is counterintuitive, as you want the ZRC product to come into direct contact with the steel for optimal adhesion and protection. Using a primer in this case would be unnecessary and could waste the product. For the best results, apply ZRC directly to the clean, prepared steel surface.
Cold galvanizing paint can be used in a wide range of applications, including assets for the oil and gas industry, transmission towers, radio broadcast towers, and marine environments. Its versatility makes it suitable for everything from NASA and DoD contracts to homeowners repairing a rusty lawnmower deck. ZRC is particularly effective on iron and steel surfaces, making it an excellent choice for various infrastructure projects, like bridges.
Additionally, ZRC cold galvanizing paint is safe for immersion surfaces, meaning it can be applied on metal assets going underwater. This makes it ideal for the bottoms of boats, cooling towers, galvanized bolts on pylons, oil rigs, and other structures in wet, salty environments. ZRC has even successfully been used on floating salmon pens and other infrastructure needed for maritime activities.
With its broad uses, ZRC is the best option for reliable corrosion protection!
Using a ZRC product ensures you achieve a strong bond between the zinc and the metal that is being protected. If you have any additional questions, we’re always here to answer them. We’re passionate about sharing our expertise to help you arrive at the best cold galvanizing paint for your project. Contact us, and our experts will lend support on a variety of topics, including ordering support, product fit, and more.