Any metallic structure has to be durable and maintain this property for as long as possible. Without a doubt, steel has a lot of strength but there are many alloys of it that are vulnerable to certain environmental conditions. When it comes to protecting the metal from corrosion, galvanizing appears to be the best option in this regard. Before coming to the main context, let’s have a look at some advantages of galvanizing and why it is performed.
- 1 What is Galvanized Steel
- 2 Why This Process is Performed
- 3 Applications of Galvanized Steel
- 4 Methods to Galvanize Steel
- 5 What Methods Are Better for Non-Industrial (Home) Projects?
- 6 What Safety Precautions Are Required Before Galvanization?
- 7 Galvanize Steel With Spray
- 8 Galvanize Steel With Special Paint
- 9 How Long Does The Coating Of Zinc Last?
- 10 Conclusion
What is Galvanized Steel
The process of galvanizing includes placing a thin coating of another metal on top of the existing one. In most cases, zinc is used as a coating material in metal structures. This protective layer of zinc protects the metal against the surrounding environment. This ability of galvanized steel to withstand harsh environmental circumstances makes it durable and perfect for open-air use.
Why This Process is Performed
The primary purpose of galvanization is to prevent rusting; that’s why galvanized steel is covered with zinc oxide. The idea behind galvanization is that the layer of zinc has to be corroded first so the steel remains safe for a far longer period. If there is no zinc coating on the metal, the chances of metal corrosion will become more significant and the metal gets corroded much quicker, as the metal is exposed to the elements.
This one is an outcome of the protective properties of the coating. Research reveals that a galvanized piece of industrial steel may serve up to 50 years in normal conditions. The same metal piece would serve up to 20 years if it is located in a highly corrosive environment where there is a lot of contact with water.
This advantage is kind of subjective but most would agree that galvanized steel looks better in comparison with most steel alloys. Usually, it’s brighter and it is way shinier with certain types of coatings.
Applications of Galvanized Steel
The use of galvanized steel is not limited. In fact, it is used in many industries like construction, energy plants, agriculture, and the sports sector. Galvanizing steel also plays a pivotal role when it comes to the construction of roads, buildings, bridges, railway tracks, gates, signal gantries, storage containers, and sculptures. So, whenever corrosion is to be avoided, galvanizing must be done to secure the metal.
Methods to Galvanize Steel
Different processes can be carried out to perform galvanizing:
- Hot-Dip Galvanizing
- Metallic Spraying
1. Hot-Dip Galvanizing
In this process of galvanization of steel, steel is immersed in a tub of molten zinc. Hot-dip galvanizing (HDG) has three basic steps; surface groundwork, galvanizing, and inspection.
In Surface groundwork, fabricated steel is brought for galvanizing, and the steel is passed through three cleaning stages; degreasing, pickling, and fluxing. Without this cleaning process, galvanizing could not be performed as zinc does not react with impure steel.
After surface groundwork, steel is immersed in 98% molten zinc having a temperature of 830F. The immersion of steel in the kettle is done at such an angle, which may allow air to outflow from tubular shapes or other pockets. It also allows the zinc to flow over and into the whole steel body. In this way, zinc comes in contact with whole steel. The iron inside steel starts reacting with zinc and forms inter-metallic coatings of zinc iron. While on the outer side, there are deposits of pure zinc coating.
The last step is performed for the checkup of this coating. Visual inspection is performed to see if there is any uncoated place on the steel body, as a coating does not stay on uncleaned steel. A magnetic-thickness gauge may also be utilized to ascertain the thickness of the coating.
The electrochemical process is carried out to make Electro-Galvanized Steel. In this process, steel is submerged in a zinc bath, and then an electric current is allowed to flow from it. This process is also referred to as electroplating.
Before the electro-galvanizing process is carried out, steel must be cleaned. Here, zinc performs the duty of anode to shield the steel. For the purpose of electrolysis, zinc-sulfate or zinc-cyanide is used as the electrolyte, while cathodes protect steel from corrosion. This electrolytic solution will allow the zinc to stay on the surface of the steel as a coating. The coating layer will be as thicker as greater will be the time of immersion in the zinc bath.
To increase the resistance against corrosion, some conversion coatings are then useful. This process creates another layer of zinc and chromium hydroxides, and the metal will show a blue-tinted surface.
Sherardizing refers to forming an identical zinc coating on the surface of the iron or steel to secure the metal from corrosion.
In this process, the steel is put in a container with divided zinc, and the container is sealed and heated to the temperature below the melting point of zinc. The result of this reaction is that two metals form zinc and iron alloys with a strong external coating of pure zinc that sticks on the surface of steel and presents considerable resistance against corrosion. This coating also facilitates better paint on the surface.
Sherardizing is the best method in the case of small metallic objects. This process is exceptionally suitable for shaped steel metal pieces, as the external layer can easily follow the patterns of the base steel.
4. Metal Spraying
In metal spray galvanizing, charged or atomized particles of molten zinc are sprayed onto the surface of the steel. The process is carried out through a handgun applicator or an exceptional flame.
Before applying zinc coating through a spray, all contaminants like unwanted surface coatings, oil, and rust must be removed. When the cleaning procedure is completed, atomized particles of molten zinc are sprayed onto the coarsened surface, and these particles get solidified on the surface.
If flaking and peeling are to be avoided, this metal spraying method of coating is the best to apply, but it is less suitable to provide considerable resistance against corrosion.
What Methods Are Better for Non-Industrial (Home) Projects?
There are two methods that may be more appropriate for non-industrial projects if protection is desired, i.e., painting and spraying the coating.
Though spray and paint may provide less corrosion protection than other methods like a hot dip galvanizing or powder coating, the effectivity will depend on the condition under which the steel will be used and the quality of the coating.
Some points to remember when painting or spraying a coating:
- It’s essential to keep the steel’s surface clean before you apply a coating for a smooth application. You can use sandpaper or a wire brush to clear off any dust or rust from the steel.
- Since there are several types of coating, it’s crucial that you choose the right paint. Go for coatings that provide better adhesion and corrosion protection.
- Use a primer before painting or spraying to allow the coating to stick and provide extra corrosion protection.
- Ensure that you evenly apply, whether it’s spraying or coating. To prevent dripping and uneven layers, avoid using a thick coating.
- Let the coating dry before handling or moving the steel.
- Once the coating is completely dry, check the steel surface carefully for defects, such as bubbles or holes, and apply an additional layer if required.
Also, the difference between insulation and coating is that the insulation method reduces heat transfer, while coating helps in protecting the surface of the material from weathering or other damages.
The pricing will depend on the size of the area to be covered, the type of coating, amount of time and work required. Compared between painting and spraying, the cost of spraying a coating is more expensive as it requires special equipment.
For painting, the cost can range anywhere from $1 to $4 per sq. foot, and for spraying, the price can be around $2 to $6 per sq. foot.
What Safety Precautions Are Required Before Galvanization?
If you’re a professional welder, metal fabricator, painter, or work with galvanized steel, it’s crucial that you take precautions while at work to avoid getting hurt. When producing galvanized steel, toxic fumes can be hazardous, so it’s best to follow the necessary steps to stay protected.
Wear PPE (Personal Protective Equipment) – This is non-negotiable. When working with equipment, wear proper protective gear, such as gloves, jacket, boots, etc. Also, before proceeding, check if your protection gears are in good condition, as you shouldn’t compromise safety.
Also, in case you want to weld steel with zinc in the future, then use proper respirators like these:
- Disposable Particulate Cup Respirator – The 3M cup respirator has at least 99.97% filtration against particles, and its cool flow system makes it suitable to wear even in humid environments.
- Half Facepiece Reusable Respirator – This is another comfortable respirator from 3M. Its quick latch design makes putting on and taking off easy, and it has a resilient silicone face seal that provides adequate comfort.
- Proper Ventilation – Before galvanizing, ensure that the area is adequately ventilated to prevent the build-up of dust and fumes. When working, keep the windows and doors open or use exhaust fans to reduce exposure to harmful fumes.
- Clear Emergency Exits – Ensure you keep first aid kits ready and remove any objects blocking the way to escape during an emergency.
- Fire Prevention – Keep the area free from flammable materials and avoid using electrical equipment that may cause sparks.
Moreover, pairing these respirators with a respirator cartridge can protect you from harmful acid gases, organic vapors, ammonia, and particulates.
Galvanize Steel With Spray
Galvanizing steel with spray typically involves using a zinc-rich coating that is applied to the surface of the steel using a spray gun or similar device. The zinc coating is excellent corrosion resistance that protects the steel from unfavorable weather conditions. This process is commonly used for structural steelwork such as refineries, radiators, transformer tanks, bridges, and windmill towers. However, we will examine home applications of this method.
Since all spray paints are not the same, it’s essential that you choose the right one so it can stick better on galvanized steel.
If you’re looking for a price-friendly option for your project, then acrylic latex-based spray paints are a suitable choice, as they’re widely available and very affordable. Though these paints are reasonably durable, they adhere well to galvanized steel.
But, if you’re looking for high-quality paints for more durability, you should go for high-build epoxy or vinyl-based paints. But the downside is that these types of paints are not readily available.
Regardless, if you are galvanizing steel using a spray, it’s essential that you first clean the steel’s surface for a smooth and even coating. But remember not to scratch too much as it may damage the steel’s coating.
Here’s a step-by-step method of galvanizing steel with a spray:
- Clean The Surface – Ensure the steel surface is free from dust, grease, rust, or other foreign matter that could interfere with the coating. It’s essential that you clean the surface before applying the zinc-rich layer so that the paint can adhere well. You can use a chemical cleaner, sandpaper, or a brush for cleaning.
- Soapy Water – Soapy water is another excellent option for cleaning galvanized steel. You can either skip or follow this step. But if you want to see satisfying results, you can use this idea. Mix the solution in heated or lukewarm water and wipe the surface using towels or unused clothes and use goggles or rubber gloves while cleaning for safety. This process can help remove the remaining dirt and provide a seamless coating.
- Rinse With Clean Water – Once cleaned with soapy water, rinse with clean water to remove any chemicals. After that, with a clean cloth, wipe the entire surface and allow the metal to dry for some time. Let it dry for about 2 to 3 hours because the paint cannot adhere well to the surface if not dried properly.
- Apply The Zinc-Rich Coating – Once the surface is arid, you can apply the zinc-rich coating. But wide varieties are available, so choose the appropriate one for your application. When preparing the coating, follow the manufacturer’s instructions and use safety equipment like gloves.
- Spray The Coating – Now, using a spray gun, you can apply the zinc-rich coating to the surface of the steel. While working, apply the spray evenly so that all sides can dry simultaneously. Don’t apply the coat thickly; it can cause the paint to drip and disrupt the coating.
- Wait For The Coating To Dry – After applying the coating, allow it to dry according to the manufacturer’s instructions.
- Check The Coating –Inspect the surface to see any defects, such as holes or bubbles, once the coating is completely dry. If there are any, you can touch up any areas that need an additional layer.
Recommended Galvanizing Sprays
Spray painting is a quick and easy way to restore corrosion protection on steel. But always make sure that the surface is cleaned appropriately before coating.
With many products available, it can take time to choose the right one. So we’ll make it easier for you if you want to galvanize steel with spray.
Here are the products that you’ll need.
Seymour Paint Zinc Rich Galvanized Coating Spray
If you want a glossy coating to match your steel surface, go for the O.E. Shiny Galv from Seymour Paint. This paint contains 65% zinc that gives a smooth finish and meets ASTM A780 performance specifications.
The Seymour 16-842 galvanized coating spray paint is a rust-preventive coating that provides a durable and long-lasting finish for galvanized metal surfaces. The paint is designed to adhere to the galvanized metal without needing a primer, making it a convenient option for easy-to-use spray paint.
This spray is also an excellent option for restoring fences and guardrails. It’s considered a sacrificial coating, is crack resistant, is durable, and works great in protecting steel and iron surfaces.
Moreover, it’s better than traditional solvent-based polymers because the coatings contain waterborne and high-solids resins. As one of the best sprays for steel protection, it’s completely free from harmful chemicals like mercury, lead, chromates, cadmium, or solvents.
- High-quality finish
- Rust and corrosion resistance
- Easy to use
- Dries quickly
- Smooth application
- Excellent coverage and adhesion
- It may require multiple coatings for coverage
- It may not blend well on heavily corroded or rusted surfaces
- Some customers complain that the nozzle clogs during use
Rust-Oleum Cold Galvanizing Spray Paint
Another suggestion on our list is the Rust-oleum compound spray paint that you can use for both interior and exterior on metal, plastics, and vinyl. This product is quite popular as it’s well-liked by customers for several reasons.
First, it has a 93% pure zinc concentration that makes it highly durable and provides maximum corrosion protection, increasing your material’s durability.
Second, it’s quick drying. Most times, it can be pretty bothersome to wait for several hours or days before applying a second coating. But with this spray, you can use as many layers as you need because it dries within 20 minutes.
Third, it gives a smooth finish, and you can even use this spray as a touch-up or repair for gutters, storage tanks, and fences.
Moreover, it meets the USDA requirements, and the high-zinc content prevents unwanted or untimely corrosion.
- Quick drying
- Highly durable
- Easy to apply
- Smooth finish
- It can be used on metal, plastics, and vinyl
- Prevents corrosion
- Some customers say that it peels off even with slight abrasion
Moeller Zinc Cold Galvanizing
The third product we have is the Moeller zinc primer. This cold galvanizing primer is another popular spray paint that contains 95% zinc, providing excellent protection from solvents and abrasions. So, no doubt, it’s highly durable. Also, it helps create a strong bond with the metal surface due to its high zinc content.
Moeller zinc cold galvanizing primer #025800 is designed to resist rust and can be used on surfaces such as aluminum, steel, iron, bare metal, fiberglass, and wood. Also, you can use it on welded joints. This primer is a quick-drying formula, and its corrosive barrier helps fight rust.
However, the drawback is that it has high VOC content, which some customers might not like. And you’ll also require additional safety equipment while using this spray as it can be harmful.
- Corrosion resistance
- Easy to apply
- Highly durable
- Quick drying
- High VOC content
- Incompatible with some coatings
Galvanize Steel With Special Paint
Painting a coating on steel is a common method to add a layer of protection and enhance its durability. If you’ve ever tried to paint galvanized steel, you must know that the paint doesn’t adhere well to the surface because of the zinc. Although it keeps the steel from corrosion, the presence of zinc makes it highly challenging as it rejects paints.
But if you’re new to galvanizing steel with paint, don’t apply paint directly on the steel, as it can peel off quickly. Also, use a rust-preventing primer to protect it from corrosion as well as to let the paint dry and adhere properly.
However, painting on steel is easy as long as you follow the proper steps and you can effortlessly do it.
Here’s a step-by-step method on how to galvanize steel with special paint:
The process is quite similar to spraying on galvanized steel.
- Clean The Surface – Before you apply paint on any surface, be it metal, steel, or iron, it’s crucial that you clean the surface by removing all the buildup of dirt as it can with the adhesion of the paint. Not only that, but it can also be challenging to apply paint smoothly if there is any dust or other contaminants. You can use a chemical cleaner or sandpaper to remove surface dust, dirt, or rust. Keeping it neat and smooth can enable you to paint the steel smoothly.
- Or Clean The Surface Using White Vinegar – If you don’t want to use chemicals or harsh items to clean the surface, you can choose a safe alternative, i.e., white vinegar. That’s right! White vinegar is a cupboard staple, so you might already have it in your kitchen. It’s non-toxic, safe, and effective compared to other solvents. To clean, pour vinegar into a bowl or cup, then take a clean cloth, soak it in the vinegar, and begin cleaning. Also, the advantage of using vinegar is that since it’s acidic, it reacts pretty well with steel, enhancing paint adherence.
- Wash With Hot, Soapy Water – Another easy option is using hot soapy water to wash the steel’s surface. If you don’t have a chemical cleaner or vinegar at home, you can use this method for cleaning. It’s pretty effective too! What you have to do is mix the solution in hot water. Then take a cloth to soak the soapy water and clean the surface. You can wear gloves for protection.
- Rinse The Surface – Once you’re done cleaning the surface using your desired method, rinse with clean water and use a clean cloth to rub off excess water or chemicals from the surface. Before moving to the next step, let the steel dry completely. Leave it for 2 to 3 hours.
- Choose The Right Paint – As you might be aware, several types of paint are available, so you have to choose the right one depending on your need. Ensure that you choose a paint that provides good adhesion to steel. Avoid alkyd or oil-based paints as they may not adhere well to the steel’s surface.
- Apply A Primer if Required – It’s recommended to apply a primer before painting a coating to maximize the paint adhesion and provide additional corrosion protection. Also, use a primer compatible with the type of paint you choose.
- Paint The Coating – Once the primer is dried, you can paint using a brush or roller. When painting, apply evenly to prevent drips or uneven surfaces.
- Let It Dry – After painting the coating, let it dry completely before you start working with the steel because it can damage the paint if not dried properly.
- Give A Final Checking – Once the paint is dried, check carefully to ensure that the paint has dried and also check for any defects to touch up any areas if necessary.
Recommended Products for Paint Galvanizing
Also, if you’re wondering what type of paints to use for galvanizing, we’ll make it easier for you.
Here are the products:
Rust-Oleum High-Performance Cold Galvanizing Compound
This matte cold galvanizing compound is a quality product. If you’re looking for a paint that offers value for money, this high-performance cold galvanizing compound from Rust-oleum should be on your list. Whether the environment is moderate or extreme, it’s meant to provide top-level performance.
This paint product provides a clean matte finish that most customers love. One significant advantage of this cold galvanizing compound is that you can apply it directly, even on a mild rusty surface.
The rust-oleum cold galvanizing compound protects metal surfaces from rust and abrasion. It contains a high concentration of zinc and forms a durable, protective layer on the surface of the metal. This product can be used on surfaces that are already rusted or on clean metal surfaces that need to be protected from rust and corrosion.
Also, another advantage of this paint is that you can apply it directly to metal surfaces without needing a primer. It dries quickly, making it suitable for use on large surfaces.
- Dries Quickly
- Highly durable
- It can be applied without using primer
- High performance
- Protects from erosion
- It may require multiple coats to achieve the desired level of protection
- It may not be as effective in extreme environments
CRC Instant Cold Rich Galvanize Coating
CRC is one of the leading market leaders in offering supreme chemical solutions. If you want to get your hands on highly specialized formulas, you should opt for the CRC zinc-rich coating that provides superior safeguarding against corrosion and rust.
Its 92% zinc coating provides a long-lasting finish, making it a good option for tough environments. Also, the advantage is that it can be used on several surfaces, such as railings, grates, fasteners, fencing, rails, doors, and more. Besides, it can also be used as a touch-up for ruined surfaces.
However, like all other products, it also has some drawbacks. When applying this paint, ensure the surface is cleaned thoroughly to ensure adequate adhesion and performance, as it may not adhere well to oily or greasy surfaces.
Also, it may not provide the same level of protection as hot-dip galvanizing or other more advanced coating systems. However, still, it’s an excellent alternative to protect the steel surface from corrosion and rust.
- Supreme quality
- Fast drying formula
- Easy to apply
- Can be used on several surfaces
- Cost-efficient alternative to hot-dip galvanizing
- May not adhere well to oily or greasy surfaces
- May not be suitable for use in highly acidic or alkaline environments
How Long Does The Coating Of Zinc Last?
Regarding durability, it usually depends on the thickness of the zinc coating—or other factors such as the type of environment, the type of zinc coating used, and the quality of the paint or spray. The thicker it is, the longer it lasts.
When comparing hot-dip galvanization with cold galvanizing coatings, hot-dip coatings tend to be more durable than cold coatings as they tend to be thick and durable. Hot-dip galvanization involves dipping the metal in molten zinc, but in the cold galvanizing method, a single coat or two is sprayed or painted.
In terms of durability, a hot-dip galvanized coating can last for over 50 years, regardless of the environmental conditions. In contrast, cold galvanizing coatings can last a few months or several years, depending on the coating layer.
Besides, it may not last as long in highly corrosive environments like industrial settings. So, choosing a high-quality zinc coating and protecting it over time is essential for maximum protection from corrosion, abrasion, and rust.