Galvanized Nails 101: All You Need to Know About Galvanization

The information about steel nail galvanizing on the internet is really spread out and inconsistent. While creating this guide, we stumbled upon a lot of contradicting facts about this topic. So we decided to gather all the correct data about steel nail galvanizing in one place for your own comfort. I hope you will find what you’ve been looking for here; if not, there are a few links leading to other sources that might be useful. So, without further ado, let’s get started.

1. Understanding Galvanization

Galvanization is a process by which a protective zinc coating is applied to steel products to shield them from corrosion. This coating acts as a protective layer, preventing the underlying steel from coming into contact with corrosive elements such as moisture and oxygen.

There are a few primary methods of galvanization: hot-dip galvanization, thermal diffusion galvanization, mechanical zinc plating, and electro-galvanization. Each method has its advantages and disadvantages, making it important to carefully consider which method is best suited for the specific application.

Now that we have a basic understanding of galvanization, we can further explore the mentioned methods in more detail.

2. Galvanization types

a) Hot-dip Galvanization (HDG)

Hot dip galvanizing is a widely used method for applying a protective zinc coating to steel nails, offering unparalleled corrosion resistance and durability. The process involves several stages, each carefully executed to ensure optimal adhesion and coverage of the zinc coating.

Surface preparation: The first step in hot dip galvanizing is preparing the steel nails for coating. This typically involves thorough cleaning to remove any dirt, grease, or other contaminants from the surface of the nails. There are two stages of nail surface preparation: Pickling and Fluxing.

Pickling is when steel nails are immersed in a solution, usually hydrochloric acid or sulfuric acid. This acidic solution removes any remaining oxides or scales from the surface of the nails. Once the nails have been pickled, they are immersed in a flux solution to clean the surface further and promote the adhesion of the zinc coating. The flux solution typically contains zinc ammonium chloride or zinc chloride, which reacts with the steel surface to form a protective barrier against oxidation during the galvanizing process.

Galvanizing: The nails are then immersed in a bath of molten zinc, heated to a temperature of around 450°C (842°F). As the nails are submerged in the molten zinc, a metallurgical reaction occurs between the zinc and the steel surface, forming a series of zinc-iron alloy layers known as the zinc-iron intermetallic layers. These layers provide the nails with superior corrosion resistance and mechanical properties.

High RPM spinning: After the nails have been galvanized, they are quickly removed from the molten zinc bath and spun in a drum. This process removes excess zinc and distributes it evenly on the nail surface.

Finishing: The galvanized steel nails may undergo additional finishing processes, such as inspection, drying, and post-treatment. The inspection involves checking the nails for any defects or irregularities in the coating while they are drying, ensuring that the nails are free from moisture before they are packaged and shipped to customers.

Result: The zinc layer thickness obtained through the HDG process varies from 43 to 86 μm (1.7–3.4 mils). Some nail manufacturers provide a double-dip option. It may seem like double-dipping would mean twice the zinc layer and twice the lifespan of the fastener. However, the galvanized coating after the second dip, with the same immersion times, is just slightly thicker than the initial coating. There is a short article on the “American Galvanizers Association” website explaining why double-dipping has just a slight effect on overall layer thickness.

b) Thermal Diffusion Galvanizing (TDG)

The Thermal Diffusion Galvanizing (TDG) method, also known as sherardizing, is quite different from the Hot-Dipped Galvanizing (HDG) process.

Preparation: Instead of using acidic chemicals for surface cleaning, the products are first cleaned with a blasting process. This is a much more environmentally friendly process because there is no waste left

Galvanization: Cleaned nails are put into a sealed barrel oven along with a special zinc powder. Inside the oven, heated to 400 °C (750° F), the zinc powder turns into vapor. This vapor integrates and diffuses into the surface of the metal, effectively becoming part of the component, which means that the surface is resistant to mechanical damage. To make sure all parts get coated evenly, the barrel oven rotates. The amount of zinc used is carefully calculated based on the size of the parts, which helps control the thickness of the coating and minimizes waste.

Finishing: After coming out of the oven, the nails are given special topcoats and sealers to finish the process, which prolongs the anti-corrosion effects even more. Finally, the parts are cooled down and checked to make sure they meet quality standards before they’re sent out.

Result: The zinc layer thickness achieved by the TDG method varies from 25 to 80 μm (1-3 mils). Though the layer of TDG is thinner, that does not mean it has a lower corrosion protection level. According to tests made by other companies (Test 1, Test 2, and Test 3), the corrosion protection was superior to the HDG method and showed better results.

However, the entire TDG process is costlier compared to HDG, with restrictions on batch sizes, and it typically requires six to eight hours to finish applying the coating because of specific requirements. Also, you might be hard-pressed to find TDG nails on the fastener market.

c) Mechanical Plating, aka Peen Plating

Mechanically plated nails, also known as peen-plated nails, have emerged as an alternative to HDG.

Preparation: In this process, cold nails are placed in a rotating barrel along with zinc dust, small glass beads called “BBs,” and an activator fluid.

Galvanization: As the barrel rotates, the BBs effectively hammer or peen the zinc dust onto the surface of the nails. While this method typically results in clean threads, the coating tends to be thin near the edges and underneath the nail head due to the limitations of the mechanical plating process. Additionally, the coating is 25% less dense than a hot-dip galvanized coating and lacks the same level of abrasion resistance. Because the corrosion protection is determined by the thinnest section of the coating, a typical coating lifetime of 10–15 years can be expected for exterior applications.

Finishing: To enhance the coating’s strength, the nails may optionally undergo immersion in a chromate rinse, which improves their corrosion resistance and durability. After the production is dried, it is packaged and sent to customers.

Result: The zinc layer thickness achieved by peen plating is inconsistent. Typically, the effective zinc thickness is 38.1 μm (1.5 mils). But it might vary from 5 to 110 μm (0.2–4.3 mils), depending on tumbling time. Additionally, the coating is 25% less dense than using a hot-dip galvanizing method. With these inconsistencies on the surface, the longevity of the fastener is compromised, and a 10 to 15-year coating lifetime can be typical for exterior applications.

d) Electro-galvanizing

Litnaglis has its own electro-galvanizing plant, where 100 tons of production are galvanized every month.

Preparation: We begin by cleansing the nails to eliminate any dirt, oil, or other impurities from the surface. This can be accomplished using a solvent-based acidic cleaner or a degreasing solution. Following the cleansing process, the nails undergo a thorough rinsing with fresh water. Subsequently, the surface of the nails must undergo activation to enhance adhesion. Typically, this involves immersing the nails in an acid solution, such as hydrochloric acid or sulfuric acid, for a short duration. The acid etches the surface, creating a rough texture that enhances the bonding of the zinc coating. Once the surface activation is complete, the nails undergo another thorough rinsing with clean water to eliminate any remaining acid or impurities.

Galvanizing: The nails are then submerged in a zinc-plating solution and subjected to an electric current to deposit a layer of zinc onto the surface. The electric current activates the zinc atoms, causing them to adhere to the steel nail surface, thereby coating it with a thin layer of zinc. We have the ability to control the thickness of the zinc layer, which can vary from 3 to 12 μm.

Finishing: Finally, the nails undergo one last rinsing with fresh water, are transported to the drying area, and are left to cool down naturally.

Result: The EG zinc layer is the thinnest of them all, ranging from 3 to 12 μm (0.12–0.47 mils). These nails are more suitable for indoor use, but if these electroplated nails are employed for outdoor tasks like roofing, their thin coating typically offers a lifespan of 5–10 years. Subsequently, rust may become noticeable on the nail head.

Despite the appealing glossy appearance of electro-plated nails, it’s not cost-effective to achieve a sufficiently thick coating to ensure reliable corrosion resistance for outdoor applications. The thin zinc layer tends to oxidize quickly when exposed to the elements, leading to the rapid rusting of nails. In essence, while plated nails offer a strong grip due to clean threads, they lack the substantial zinc coating necessary to prevent rusting and staining.

3. Why Zinc?

In the world of construction, zinc has been a trusty companion for over 150 years, shielding steel from the ravages of corrosion. Whether it’s through hot-dip galvanizing or other innovative coating methods, zinc has been there to ensure that our buildings stand strong and sturdy.

Ok, but why zinc? Maybe there are better alternatives? Well, first of all, zinc is a very reactive metal. The only two metals that are more reactive than zinc are aluminum and magnesium. However, zinc has more positive properties when it comes to galvanizing and protection from corrosion.

In the presence of natural wet and dry cycles occurring in the environment, various zinc corrosion byproducts emerge on the coated surface. These byproducts, including zinc oxide (ZnO), zinc hydroxide (ZnHO2), and zinc carbonate (ZnCO3), combine to form the zinc patina. This patina serves as an extra layer of passive, insoluble protection for the hot-dip galvanized coating. Once established, the zinc patina significantly reduces the corrosion rate of zinc to approximately 1/30th that of steel exposed to the same environment. Also, due to zinc’s abundance in nature, the price plays a significant role. These are the main factors that make zinc the best option for galvanizing.

4. Importance of Galvanized Nails in Construction

Nails are galvanized in order to stop or at least slow down the corrosion process, which is the main issue with ferrous metal-based products. Rust gradually eats metal away, which weakens its structural integrity. This deterioration can pose serious safety risks in structural applications. Also, rust creates a reddish-brown discoloration on the surface of ferrous metals and their surrounding surfaces, detracting from their appearance. This can be particularly problematic in applications where aesthetics are important, such as architectural elements or decorative items.

That is why nails are coated with a layer of zinc, which helps prolong the lifespan of ferrous metal products. But how do we know how long galvanized fasteners are going to last? Well, there is a useful tool developed by Dr. X. G. Zhang that helps you calculate the longevity of galvanized fasteners in a specified area. It is called a Zinc Coating Life Predictor. The instructions for this “calculator” are pretty straightforward; you fill out your specified location’s atmospheric conditions (which can be easily found on Google), and then in the next step, you have to write the zinc thickness of your fasteners. We already know the most popular galvanization types and their optimal zinc layer thickness.

• EG from 3 to 12 μm. (typically 12 μm.);
• MP from 5 to 110 μm. (typically 38 μm.);
• TDG from 25 to 80 μm. (typically 25 μm.);
• HDG from 43 to 86 μm. (typically 50 μm.);

For fun sake, we filled in and calculated how long an HDG nail with a layer of 50 μm. would last in our local outdoor conditions. The results showed that it would take 89.3 years for HDG protection to wear off, losing 0.6 μm of zinc layer every year.

5. Pros & Cons of Each Galvanization Type

Electro-galvanizing

👍Advantages:

• Precise coating thickness: It allows for precise control over the thickness of the zinc coating, ensuring uniformity and consistency.
• Good for complex shapes: Electro galvanizing is suitable for coating complex-shaped objects and small parts with intricate details.
• Smooth finish: It produces a smooth and aesthetically pleasing finish, making it suitable for decorative applications.
• Environmentally friendly: It generates fewer emissions and waste compared to some other galvanizing processes, making it relatively environmentally friendly.

👎Disadvantages:

• Limited coating thickness: Electro-galvanizing typically results in thinner zinc coatings compared to other galvanizing methods, which may offer less corrosion protection in certain applications.
• Surface preparation required: Proper surface preparation is essential to ensure good adhesion and uniform coating, which can increase processing time and cost.
• Vulnerable to mechanical damage: The thin nature of the coating makes it more susceptible to scratching and mechanical damage, compromising its corrosion resistance.
• Not suitable for large parts: It may not be suitable for galvanizing large or bulky parts due to limitations in tank size and handling capabilities.
• Lower corrosion resistance in harsh environments: Electro-galvanized coatings may not offer sufficient protection against corrosion in highly corrosive or extreme environments compared to other galvanizing methods.

Mechanical Plating

👍Advantages:

• No heat distortion: Peen plating is a cold process, that eliminates the risk of heat distortion in the metal substrate, which is particularly important for heat-sensitive materials.
• Improved surface adhesion: The mechanical action of peening helps promote excellent adhesion between the substrate and the zinc coating, enhancing durability and longevity.
• Fast processing time: Peen plating can be a relatively quick process, allowing for efficient production rates and shorter turnaround times compared to some other galvanizing methods.
• Enhanced corrosion protection compared to EG: Peen plating provides better corrosion resistance, comparable to EG, making it suitable for outdoor environments.

👎Disadvantages:

• Surface preparation required: Proper surface preparation is essential for peen plating to ensure good adhesion and coating quality, adding to the processing time and complexity.
• Potential for surface damage: The mechanical process of peen plating can introduce surface imperfections or damage if not properly controlled, affecting the appearance and performance of the coated parts.
• Inconsistent coating thickness: It is hard to get a uniform coating under the nail head and point. Also, the protective layer is about 25% less dense than the HDG coating.

Thermal Diffusion Galvanizing

👍Advantages:

• Uniform coating: Thermal diffusion galvanizing provides a uniform and consistent zinc coating thickness across the entire surface of the substrate, ensuring reliable corrosion protection.
• High corrosion resistance: The zinc coating produced through thermal diffusion galvanizing offers excellent corrosion resistance, making it suitable for use in aggressive environments.
• No risk of hydrogen embrittlement: Unlike some other galvanizing methods, thermal diffusion galvanizing does not pose a risk of hydrogen embrittlement to the metal substrate.
• Long-lasting protection: Thermal diffusion galvanizing creates a durable zinc-iron alloy layer that adheres strongly to the substrate, providing long-lasting corrosion protection.
• Environmentally friendly process: No acids or chemicals are used in this galvanizing method.

👎Disadvantages:

• Longer processing time: Thermal diffusion galvanizing typically requires longer processing times compared to some other galvanizing methods, which may impact production efficiency.
• Surface preparation required: Proper surface preparation is crucial to ensure the effectiveness of thermal diffusion galvanizing, adding complexity to the process and requiring additional steps.
• Pricey option: TDG products tend to be more expensive than HDG metal products.
• Rare coating option for nails: It is hard to find a distributor who supplies nails for pneumatic nailers with such coating.

Hot-Dip Galvanizing

👍Advantages:

• Excellent corrosion protection: Hot dip galvanizing provides robust and long-lasting corrosion resistance, making it ideal for outdoor applications, marine environments, and harsh industrial settings.
• Complete coverage: The hot dip galvanizing process ensures thorough coverage, including complex shapes and hard-to-reach areas, providing uniform protection across the entire surface.
• Low maintenance: Once galvanized, the coated surface requires minimal maintenance over its service life, reducing the need for frequent inspections and repairs.
• Durability: Galvanized coatings are highly durable and can withstand mechanical damage, abrasion, and exposure to extreme weather conditions, extending the lifespan of the coated structure or component.
• Cost-effective: While the initial cost of hot dip galvanizing may be higher compared to other coating methods, its long-term durability and low maintenance requirements often result in cost savings over the lifespan of the treated object.

👎Disadvantages:

• Initial cost: Hot dip galvanizing can be more expensive upfront compared to some other coating methods, which may deter budget-conscious projects or applications with tight financial constraints.
• Aesthetic appearance: The appearance of hot dip galvanized surfaces may not be as visually appealing as other coating options, as they typically have a characteristic matte gray finish that may not suit certain architectural or decorative applications.
• Limited thickness control: The thickness of the galvanized coating can vary, and it may be challenging to achieve precise coating thicknesses, which can be a concern for applications with strict dimensional tolerances.

6. Applications of Galvanized Nails

Hot dip galvanized nails are extensively used in outdoor construction projects such as fencing, decking, and framing. The robust corrosion protection provided by HDG makes these nails ideal for applications where exposure to moisture, humidity, and harsh weather conditions is common. They are also commonly used in marine environments due to their excellent resistance to saltwater corrosion.

Thermal Diffusion Galvanizing: Nails treated with thermal diffusion galvanizing find applications in industries where high corrosion resistance and consistent coating thickness are critical, such as infrastructure and marine construction projects. The uniform zinc coating achieved through this process ensures reliable protection against corrosion, making these nails suitable for use in structural applications such as bridges, decks, piers, fencing, and more.

Mechanically plated nails are preferred in applications where a thin, uniform zinc coating is desired without the risk of hydrogen embrittlement, making them suitable for fastening materials with stringent dimensional tolerances. They also find use in decorative applications where a visually appealing finish is required, such as furniture and architectural fixtures.

Electrogalvanized nails are commonly employed in indoor applications where moderate corrosion resistance and a smooth, aesthetically pleasing finish are desired, such as furniture assembly, interior carpentry, and light-duty construction. The thin zinc coating applied through the electroplating process provides sufficient protection against rusting while maintaining a sleek appearance.

7. Common Myths About Galvanized Nails

Galvanized nails have long been favored for their corrosion-resistant properties, making them a popular choice for outdoor construction projects and applications exposed to harsh environmental conditions. However, several myths and misconceptions surround galvanized nails. Here are some common myths debunked:

Myth: Galvanized nails never rust.

Reality: While galvanized nails are highly resistant to corrosion, they are not completely immune to rusting. Over time and under certain conditions, such as prolonged exposure to saltwater or acidic environments, galvanized nails may develop rust spots or corrosion. However, compared to untreated nails, galvanized nails offer significantly better protection against rust and can significantly prolong the lifespan of structures and materials.

Myth: Galvanized nails are suitable for all outdoor applications.

Reality: While galvanized nails are generally well-suited for outdoor use, not all galvanized nails are created equal. Factors such as the thickness of the galvanized coating, the quality of the galvanizing process, and the specific environmental conditions can affect the performance of galvanized nails. In some cases, specialized coatings or materials may be required for extreme environments or applications subject to high levels of corrosion.

Myth: Galvanized nails are weaker than non-galvanized nails.

Reality: Galvanized nails undergo a galvanizing process that does not significantly weaken the base metal. In fact, galvanized nails maintain comparable strength and durability to their non-galvanized counterparts. However, improper handling or storage of galvanized nails, such as exposure to excessive heat or moisture, can potentially compromise their integrity and performance.

Myth: Galvanized nails are more expensive and not worth the investment.

Reality: While galvanized nails may have a slightly higher upfront cost compared to untreated nails, their long-term benefits far outweigh the initial investment. Galvanized nails offer superior corrosion resistance, which can prevent costly damage, repairs, and replacements over time. Additionally, the increased lifespan of structures and materials due to the use of galvanized nails can result in overall cost savings in the long run.

Myth: Galvanized nails require special handling or maintenance.

Reality: Galvanized nails do not require any special handling or maintenance beyond standard best practices for fasteners. However, it’s essential to store galvanized nails properly to prevent exposure to moisture or other corrosive elements before installation. Additionally, selecting the appropriate type and size of galvanized nails for specific applications can ensure optimal performance and longevity.

By understanding the realities behind these common myths, builders, contractors, and DIY enthusiasts can make informed decisions when selecting and using galvanized nails for their projects, ensuring reliable and durable results.

8. Future Trends in Galvanization Technology

As industries continue to evolve and technology advances, several trends are emerging in galvanization technology that are shaping the future of corrosion protection and surface coating solutions.

Advanced coating formulations and alloys. Future advancements in galvanization technology are expected to focus on developing new and improved coating formulations with enhanced corrosion resistance, durability, and environmental sustainability. Researchers are exploring innovative alloy compositions, nanoparticle additives, and surface treatments to create coatings that offer superior protection against corrosion while reducing the use of hazardous chemicals and heavy metals.

A recent advancement involves the introduction of aluminum-magnesium-silicon-zinc alloy-coated steels. Nippon Steel has developed a hot-dipped steel sheet product with a surface composition of 11% aluminum, 3% magnesium, trace silicon, and 86% zinc, conforming to ASTM A1046-06 standards. According to their claims, this coated steel sheet offers extreme corrosion resistance.

Nano-coating technologies. Nanotechnology holds great promise for revolutionizing galvanization processes by enabling the development of ultra-thin, highly uniform coatings with exceptional performance characteristics. Nano-coatings offer increased surface coverage, improved adhesion, and enhanced barrier properties, making them ideal for protecting steel and other metal substrates in demanding environments.

Smart coatings and self-healing materials. The integration of smart coatings and self-healing materials into galvanization technology is expected to become increasingly prevalent in the future. These advanced coatings are designed to autonomously detect and repair damage caused by corrosion, mechanical wear, or environmental factors, thereby extending the lifespan of coated surfaces and reducing maintenance requirements. Smart coatings may incorporate responsive polymers that trigger repair mechanisms in response to changes in environmental conditions.