January 17, 2024
We often get questions regarding zinc, as many of our customers either aren’t aware of its significance or know it’s needed but aren’t quite sure why. This is why an in-depth exploration of zinc-rich paint and its pivotal role in preventing rust on metal surfaces is so important for those looking to keep their transmission towers, commercial boats, gates and fences, HVAC cooling towers, welding projects, and other structures free of corrosion.
In this blog, we will delve into the multifaceted world of zinc, highlighting its significance in industrial applications — particularly in the fight against corrosion. Whether you're interested in understanding how zinc-rich paint protects metal from rust, learning about why ZRC Cold Galvanizing Compound works so well, or exploring the science behind zinc-rich compounds, we've got you covered. We’re not here to just sell; we want to educate our customers on the importance of zinc in safeguarding metal integrity in a wide range of industrial settings.
What is Zinc?
In the context of paint and rust prevention, zinc is a key component of zinc-rich coatings that are often used as a protective layer on metal surfaces. A zinc-rich coating is a surface layer that contains a high percentage of zinc dust which sacrificially corrodes when in direct contact with steel.
Zinc plays a crucial role in these coatings by acting as a sacrificial anode, meaning that it corrodes preferentially to the underlying metal. This sacrificial corrosion helps prevent rust by forming a protective barrier over the metal substrate. Zinc-rich paints provide an effective defense against corrosion and extend the lifespan of the coated metal. They provide cathodic protection to metals that’s similar to that provided by the hot-dipped galvanizing process.
The zinc content in these paints serves as a durable shield, creating a barrier that inhibits the corrosive effects of environmental elements and enhances the overall durability of metal surfaces.
Does Zinc Rust?
Is zinc rust proof? You may read the above answer and think that means zinc doesn’t rust. That’s a common misconception, but a misconception nonetheless. Zinc will eventually undergo the process of corrosion, but it forms a protective layer that prevents further deterioration. When exposed to oxygen and moisture, zinc reacts to create zinc oxide, which acts as a barrier against corrosion. This protective layer is crucial in preventing rust and is why zinc is used as a sacrificial anode in our anti-corrosion compounds. The zinc sacrificially corrodes instead of the underlying metal and provides effective corrosion protection for the coated material.
A zinc-rich compound has a significantly longer lifespan than that of unprotected, oxidized metal; but it, too, corrodes. Eventually, it will need to be replaced. When that time comes, simply sand or grind the original coating down to remove the zinc hydroxycarbonate salt that has formed. Then, apply a new cold galvanizing compound to keep corrosion at bay.
How Does Zinc Prevent Corrosion?
How does it work? How does rust form? These are common questions. To understand how, one must know that a less noble metal will corrode at a faster rate than a nobler one. Zinc-rich compounds can be applied by spray or by brush (like a paint) to steel. Zinc, being less noble than steel, forms hydroxycarbonate salt when it corrodes. This salt bonds with the existing zinc in the film coating, creating an advanced, self-healing film that ensures the metal surface beneath the coating stays protected.
Step 1: Apply ZRC to steel
Step 2: Weather damages the steel
Step 3: Hydroxycarbonate salt bonds with the existing zinc in the film. This self-healing process creates a dense, impervious, galvanic coating that is resistant to weather, water, and fumes.
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Does Steel Rust With a Zinc Surface Layer?
If left untouched, metal will eventually corrode. Even metal that was initially treated must be maintained in order to keep it rust-free. We recommend you reapply ZRC about once a year, depending on the weather in your area.
Does the Quality of Zinc Matter?
Absolutely! There are three factors that affect the quality of zinc-rich cold galvanizing compound. Perhaps the most important is the quality of the dust itself, meaning the purity of zinc dust being used. You see, zinc dust is mined out of the earth; it is a natural product. There is simply no way to mine it without scooping up some impurities along with the raw state. Zinc dust has a lot of impurities, so producers refine it and take these impurities out.
It may go without saying that different companies take out different levels of impurities. This is why the ASTM D520 regulates the Standard Specification for Zinc Dust Pigment. There are three levels: Type I, Type II, and Type III — each pertaining to the purity of the zinc dust in the product.
Type I is not very pure. This compound can have lead, chlorine, cadmium, sulfur, and plenty of other nasty stuff. If you settle for Type I, you may be buying zinc dust, but you are only getting 94% pure zinc. The other 6% is little more than filler that gives poor corrosion resistance — toxic garbage, in fact.
Type III, at the opposite end of the spectrum, requires the zinc to be extremely clean and pure. It is about 97% pure, which makes a big difference in the quality of the coating and how much protection it gives.
How Can I Apply Zinc?
There are actually a few different ways to apply ZRC. If you need to climb a ladder to apply the product, you can use ZRC in an aerosol spray can. On top of that, aerosol is the best product for your project if you're simply touching up an existing corrosion protection solution. Our experts recommend the brush-on applications when you’re undergoing a high-volume project, like steel girder I-beams. If you have a big job ahead, we recommend liquid paint. This is because you will get more coverage from a gallon of cold galvanizing paint than a spray can.
When Will I Need To Reapply Zinc?
It all depends on the environment. A steel structure in a chemical plant is going to be corrosion-proof for a relatively short amount of time because of corrosive materials in the air, like chlorine and acids.
What conditions create rust? One word: moisture. If you’re out in the dry desert, the zinc will last much longer. Everything from how close the structure is to salt water to the humidity of the air and beyond — it all affects the life expectancy of a zinc product.
There are a lot of different factors at play, but we encourage you to reapply ZRC once a year as a general rule.
Is It More Expensive To Use a Zinc-Rich Paint?
Yes, it is — but it’s also worth it. Zinc-rich paint, tailored to combat rust, differs significantly from regular paint due to its unique composition and protective mechanism. Unlike standard paint, zinc-rich paint contains a high concentration of zinc dust or particles within its formulation.
The key distinction lies in the role of zinc as a sacrificial anode. When zinc-rich paint is applied to a metal surface, the zinc particles act as sacrificial corrosion agents. In the presence of environmental factors like moisture and oxygen, it is the zinc within the paint that undergoes corrosion rather than the underlying metal. This sacrificial corrosion forms a protective barrier of zinc oxide on the metal surface, effectively preventing rust from developing.
Regular paint lacks this sacrificial property and does not offer the same level of corrosion resistance. Zinc-rich paint provides an added layer of defense against rust that regular paint simply can’t match, making it a preferred choice for applications where corrosion protection is needed, such as in the coating of steel bridges.
If you’d like to learn more about this, check out this digital brochure.
Do You Need To Remove Zinc From Previously Galvanized Sheet Steel?
In this case, no. This is a form of galvanizing on sheet metal, and so you don't. It still has electrical conductivity, and will not act as a barrier that reduces the effectiveness of ZRC products.
That being said, you will want to prep the surface area before adding a new layer of ZRC Cold Galvanizing Compound. Be sure you remove paint chips, oil, grease, dirt, and mildew so the paint adheres directly to the metal with nothing sitting on the surface.
Trust ZRC For Your Zinc-Rich Paint Needs
The pivotal role of zinc in the relentless battle against rust cannot be overstated. Whether you're safeguarding our nation’s vital infrastructure or preserving the integrity of commercial metal surfaces, the use of zinc-rich coatings stands out as a proven and effective solution.
Elevate your rust prevention strategy with our premium products, meticulously designed to harness the corrosion-resistant properties of zinc. As you embark on projects that require superior corrosion protection, purchase your needed zinc-rich paint from our online store. By choosing ZRC as your rust prevention solution, you're not just investing in paint; you're investing in the longevity and resilience of your structures. Zinc offers unmatched defense against the relentless forces of rust, and our zinc is the best of the best. No one else can say that!
