Raise your hands if you have troubles with painting galvanized surfaces! Yes, to some extent, we all dealt with the same problems when it comes to this topic. The key to solving these issues is how to increase the adhesion between the surface and the paint.
Even with professional painters, they might be doing it wrong. We can see so many situations where the paint falls in big parts after just a few years in the surprise of the owners. That’s why we have done a lot of practical research on this field to find out the solution. And we did!
We hope that the article today would help you release all the worries before doing a galvanized painting project. You might or might not know about this topic, so let’s begin with:
Galvanized paint refers to a kind of paint used for galvanized metal. If painting is tough, then painting galvanized metal is even tougher. This is because this surface is covered with the oil layer to prevent rust. Therefore, this layer would eventually shed the paint.
On the other hand, the amount of zinc included in galvanized metals can also peel the paint off. To understand how difficult it is to paint this surface, let’s continue with us:
A lot of people buying tons of “high-quality” products that promise by the marketers. However, there is no such magical product like that. We also play very important roles in this process. You should understand that the key to solving the problem is the adhesion. Below we would analyze each of the issues when painting galvanized surfaces.
To put it simply, in order to prevent the white rush, galvanized surfaces are normally treated with chromates or other passivating methods. These treatments, therefore, cause troubles for the adhesion of the paint.
Having said that, before doing the painting, you should check if the galvanized surfaces are passivating treated or not. Remove it before applying any other coatings.
Prepare the Surface
A shiny and smooth galvanized metal. Sound interesting, right? However, when it comes to painting it, there might be some issues. This kind of surfaces can be hard to adhere to the paint.
That’s why it is indeed to prepare the surface. Here’s how you can do it:
First of all, remove oil and grease using SSPC SP-1 Solvent Cleaning. Secondly, make the surface become roughened by cleaning it with MPI #25 or any other chemical etching solution. Another way is to blast at lower pressures (50 psi) or with lighter abrasives to decrease the effect of zinc of the galvanized surfaces.
The Importance of Primer
Some marketers might tell you how great their paint is and why you don’t need to apply primer. Well, be careful with these advertisements. Let us tell you a story.
This happened in a shopping mall where the paint from galvanized steel parts was falling down in big chips after just a few years of painting. After doing some research, they found out that the main reason was the primers weren’t applied on the surface.
For galvanized steel, the primer is not used to resist corrosion or rust. Hot-dip zinc does that. The purpose of applying primers is to increase the adhesion between the surface and the paint. Therefore, it is really important to apply the primer.
You can use a water-based acrylic primer for this step. And in this case, MPI #134 is a good choice. For aggressive environments, replace it with MPI #101.
Alkyd Dryfall Coating
Another mistake when painting galvanized surfaces is applying an alkyd dryfall coating without covering the surfaces with primers. This causes the blistering and low adhesion due to the reaction between alkaline salts produced by zinc and alkyd dryfall coating.
To conclude this part, we want to emphasize some problems that people often make when painting galvanized surfaces.
Make sure to remove any pre-treatments. Dull and roughen the surface using some chemical solution. Apply the primers is very necessary for the adhesion. Last but not least, avoid using an alkyd dryfall coating on the unprimed surfaces.
The 4 Best Product Reviewed
The first product comes from Rust-Oleum company. This is one of the popular brands on the market. The galvanized surfaces are renewed with 93% pure zinc coating. It can cover up to 12 sq ft. You only need to wait for 30 minutes to dry it.
As it is a galvanized spray paint, the product is easy to use for everyone. The finish is smooth, durable, corrosion and scratches resistance
Pros: Cover the rust well, tough and strong, improve the look but also protect the meta, the finish is clean and rea, last for a long tim, resist corrosion.
Cons: The nozzle doesn’t work well, make sure to shake it before using, easy to scratch, take a long time to dry.
The product of ZRC is the second one we introduce to you. ZRC is a prestigious company with the success proven for 50 years. The effect of the paint is equal to hot-dip galvanizing. It can protect the surface effectively.
Plus, the quality of the product is approved by the VOC standard in 50 states. It is indeed a reliable product for you.
Pros: Stick to the surface easily. The best way to slow the rust on your vehicle. Protect your vehicle from Rust and Salt. This compound covers evenly without lumps and protects against corrosion. After painting, it looks like original galvanizing.
Cons: Haven’t found any cons of this product.
As the name “High Performance” says it all, this product from Rust-Oleum is formulated to use in harsh environments. It can bear the heat up to 200 Degree F. Moreover, it dries fast – 20 minutes. What’s more?
It is designed with the wide nozzle. Therefore, you use the less effort on your fingers and can spray from any angle.
Pros: No sign of rust, weather resistance , durability and easy to use, pretty solid for metal coating, spray well and dry quickly.
Cons: The nozzle doesn’t work well.
This product is different from the three product above as it comes in the can form. A bit more expensive, yet worth the money. When you first apply it on the surface, it doesn’t look like real galvanizing. However, it may fade into a more normal galvanized color with time.
As it is in a can, it would be a little bit hard for you to get used to it. It is thick until you stir it regularly. That said, you should ask the instruction prior to the manufacturer. The can is heavy. It might be one of the signs that it contains a lot of zinc.
Pros: Look great on the anchor when it is wet, and during drying, it looks streaky, but after it is dry (about an hour), it looks like a galvanized anchor. Easy to apply and protect rust well, even for many years afterward. The adhesion is great. Tough and durable.
Cons: Haven’t found any cons.
Above is our top 4 best products in our opinion. As you can see, ZRC products seem to have a lot more advantages than Rust-Oleum products. ZRC’s galvanized paint is more durable, protect the metal from corrosion and rust better. It is also approved by VOC standard.
Besides, so far, we haven’t found any cons related to their products. The price of ZRC products is a bit higher than the Rust-Oleum ones. Nonetheless, once you use it, you will be satisfied. It is not the end. Even if you have the best product, it would be a waste if you don’t use it correctly. So, check it out this part
As we mentioned below, galvanized surfaces require careful treatments before applying the paint. If not, the adhesion will cause you so many troubles later. This part introduces you step-by-step instruction on how to paint this kind of surfaces. There are four steps as below:
Step 1: Wash the Surface
This step is important before using any painting technique. Firstly, use hot and soapy water to wash the surface. Then wait for it to dry completely. After that, use a mixture of water and 2% ammonia to clean the surface again.
This process could take you a few hours, yet it is necessary for the next steps. Make sure to check if the galvanized metal comes with chromates or other passivating pre-treatments as these could affect the adhesion of the paint.
Step 2: Sanding
A 240 grit sandpaper is perfect for you in this step. Sand the entire surface to make sure it is cleaned from dust. Then wipe it out using tack cloths. Next, the adhesion could be reduced if the galvanized surfaces are too shiny and smooth. A lot of people skip this one causing serious damages.
We recommend you to make it dulled and roughened by using some chemical etching solution. Congratulations! Welcome to the next step.
Step 3: Apply The Primer
Now you know how important it is to apply the primer, right? These primers will bond the paint into the galvanized surface. Before using it, you should understand clearly the directions on the product package. It gives you the instructions on how to use it and how long it takes for the primer to dry.
The best is to use galvanized spray paint. Spray the objects from the top below, one part at a time. If you see any drips, remove it immediately. You can apply two-three primers depending on your purpose. Remember to let it dry before applying a new coat.
Step 4: Applying The Paint
If you have done the above steps as we instructed, this step is so much easier. You should also use the same technique as applying the primer. To increase the compatibility, you might also want to apply the paint from the same brand as the primer.
Although this is the last step, don’t be rushed. Paint it gradually to finish the job perfectly. Refer to the products we recommend above to find the suitable one for you.
Actually painting galvanized surfaces is not as hard as it sounds. However, all you need to do is to prepare the surface well before painting and choose the suitable galvanized paint. Keep in mind four things when preparing the surface: Pre-treatment, make the surface dull and roughen, applying the primer and be careful when applying an alkyd dryfall coating.
When it comes to this kind of painting, using galvanized spray paint is easier than using rollers or brushes. We also give you a list of highly recommended products with its features. This list is endless and we want to update it regularly. If you have any fabulous products, share them with us in the comment below.