Polyurethane is generally a plastic material that we use in different fields. We often use polyurethane as a sealing of coating material.
Whenever we want to protect something from moisture or corrosion, we use polyurethane. Even polyurethane can stick to most of the surfaces.
So, you might be interested in whether you can use polyurethane on metal or not. Generally, polyurethane has different bonding characteristics on different surfaces.
So, you have to know the bonding quality between polyurethane and metal. Moreover, knowing the consequences of using polyurethane on metal is also essential.
Can you use polyurethane on metal?
You can use polyurethane on metal. Generally, polyurethane is available as both semi-hard and liquid forms to use on metal. Moreover, polyurethane is popular to use as a hard metallic finish. Besides, polyurethane is useful on metal because it has low VOC than other plastic products.
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However, you might be confused about which surface of metal you can use polyurethane. Sometimes, metal can be painted or sometimes bare metal.
Sometimes, additional materials might be needed for effective polyurethane. So, let’s see whether you can use polyurethane on different surfaces of metal.
Painted metal:
You can use polyurethane on painted metals. Generally, polyurethane is an excellent material to seal the metal surface. Even polyurethane makes the painted metal surface more enhancing.
Moreover, polyurethane seals the painted metal surface. That means it doesn’t allow moisture or corroding materials to come into contact with metal. So, the painted metals remain protected.
Besides, different metals are suitable to use polyurethane on them. For example, steel, aluminum, iron, etc., metals are suitable to seal with polyurethane. When these metals are painted, they are perfectly ready to use polyurethane on them.
If the surface doesn’t have any painted surface or primer, the polyurethane will not be effective. Otherwise, you will need to abrade the surface so that the plastic material stick to the metal surface.
Bare metal:
Generally, liquid and clear polyurethane will not stick to the bare metal. When the polyurethane will dry, it will chip off from the surface. So, you will not a primer to make polyurethane stick to the metal surface.
Generally, different types of metals are good to use polyurethane. For example, iron, steel, copper, aluminum, etc., metals are suitable for sealing with polyurethane.
But if these metals are bare without any primer or paint, polyurethane will not durable to these surfaces.
Polyurethane is a rubbery plastic material that has a hard and durable finish. But using a caustic primer or epoxy primer is essential. Then the polyurethane will stick to the metal surface and protect it properly.
Will polyurethane adhere to metal? Can you use water based polyurethane on metal?
Yes, polyurethane will adhere to metal. But you will have to prepare the surface first. If you don’t use any primer material to the metal surface, clear polyurethane will not stick to the metal surface. That’s why a painted metal surface is perfect to use polyurethane.
Polyurethane is a hard plastic finish that seals and protects metal from environmental effects. Sometimes, people paint metal surfaces to protect them from corrosion.
But polyurethane will be the best as a protecting hard surface. Moreover, polyurethane provides low volatile compounds that are harmful to the environment.
Water-based polyurethane can also be used on the metal surface if the polyurethane has the quality to stick to the metal surface.
Generally, it is often mentioned in the labeling whether the water-based polyurethane is suitable to use on metal or not. But if the metal surface is painted earlier, you can use water-based polyurethane on that surface.
How to prepare metal for polyurethane?
You might have already known that you can’t use polyurethane on bare metal. The polyurethane might not adhere to the bare metal. So, you have to prepare the metal first. Let’s see how you can prepare metal for polyurethane.
Cleaning:
Like the other coating processes, you must clean the metal surface first. You have to clean dirt, dust, grease, and other residues. For removing grease, you can use mineral spirits. Moreover, you can use detergent to remove organic dirt.
Removing old paint:
If the metal surface has old paint, you have to remove that paint first. Sanding is the most effective way to remove old paint. You can also use a brush or scrub the surface to clean old paint.
Many people use power tools to remove old paint, but it can produce high heat and damage the metal surface. So, you have to remove old paint carefully.
Removing rust:
You also have to remove rust from the metal surface. Metals often get rusted by the environmental effects. So, you have to remove rust by sanding. Many rust-inhibitive primers, rust converters, etc., are available to remove rust from the metal surface.
Repairing:
Now you have to repair the metal surface from debris, holes, dents, etc. These problems might affect the polyurethane after installing. So, you have to repair these problems first. You can use an epoxy filler to repair the small and large holes.
Priming:
The final preparation step is to use a suitable primer for the metal surface. Without primer, the polyurethane will not adhere to the metal.
So, you have to use a primer that is suitable. Try to avoid water-based primer. You can use an oil-based or epoxy-based primer. Generally, iron oxide and zinc chromate primer are suitable to use on metal surfaces.
What happens if you don’t use primer on metal before polyurethane?
If you don’t use primer on metal before polyurethane, the polyurethane will not be effective. The metal surface will start to rust and corrode.
Moreover, the metal surface will be exposed to environmental effects and weaken the metal. Ultimately, the metal will face different types of failure.
So, you must use primer on metal before polyurethane. If you don’t use primer, the polyurethane will not stick to the surface. Moreover, the polyurethane will not create a protective surface.
The coating might seem okay, but after some days, the polyurethane coating will start to corrode. So, primer is essential for using polyurethane on metal.
How to use polyurethane sealant on metal?
When you want to use polyurethane sealant on metal, you have to follow an appropriate process. Let’s see how you can use polyurethane sealant on metal.
Preparation:
Before using polyurethane, you must prepare the metal surface. Otherwise, the sealant will not adhere to the metal. For example, you have to clean the surface from all types of dirt and grease. Moreover, you have to sand the surface to remove old paint and rust.
Besides, you have to remove all the debris and impurities that are visible. Then you have to fill the small and large holes with epoxy fillers.
Primer:
One of the most important steps is to use primer on the metal surface. You can use iron oxide and zinc chromate primer on the metal surface. Primer is necessary to make polyurethane durable and effective.
Applying polyurethane:
Then you have to use liquid polyurethane on the metal surface. You can also use semi-hard polyurethane according to your preference.
You can use a brush or roller to use the sealant on the surface. If you want a thick coating, you can use multiple coatings of polyurethane on the metal. Let the surface dry and cure for a sufficient time.
Will polyurethane prevent rust on metal?
Yes, polyurethane will prevent rust on metal. But for this, you have to apply the polyurethane properly. For example, if you prepare the metal surface well and use a primer before polyurethane, the polyurethane will work well as a sealant and protect the metal.
This protection will be effective from rusting. Otherwise, the polyurethane will not work properly, and eventually corrosion and rusting will take place.
Generally, if properly used, polyurethane is an excellent sealant for preventing rust on metal.
Which is more durable polyurethane or lacquer on metal? Lacquer vs polyurethane on metal
Generally, polyurethane is more durable on metal. Let’s see the difference between polyurethane and lacquer.
Durability:
Polyurethane is a hard polish over metal and creates a thick coating than lacquer. On the other hand, lacquer is a thin coating that penetrates the porous materials often. So, polyurethane is more durable than lacquer on metal.
Cracking and discoloration:
Polyurethane prevents cracking and discoloration. Generally, the hard surface of polyurethane prevents cracking and discoloration well than lacquer. Because the thin coating of lacquer doesn’t provide hardness against cracking and discoloration.
Though polyurethane is susceptible to heat, it is more durable than lacquer considering the cracking and discoloration protection, thick and hard coating, etc.
Final Thoughts
Polyurethane is a great coating to seal, protect, and enhance the metal surface. If you use polyurethane on metal, the metal will be durable and protective against rust. But you must take necessary preparation and use a primer before polyurethane. Otherwise, it will not stick to the surface.