Whenever it comes to applying a clear coat over a surface, you might have thought about polyurethane. Generally, polyurethane is a clear coat that provides a protective, glossy, and transparent layer. Besides, shellac is also a popular coating to provide protection.
So, you might be confused about whether you can put polyurethane over shellac or not. Well, polyurethane and shellac both are coating materials. So, you have to know the safety of using one over another.
Moreover, knowing the consequences of using polyurethane over shellac is also essential.
Can you put polyurethane over shellac?
You can put polyurethane over shellac. Generally, shellac is already an excellent sealant. So, it’s not compulsory to put polyurethane over shellac. But if you want to apply polyurethane over it, you can do it. Because shellac is pretty compatible to go under oil or water-based polyurethane.
However, polyurethane can also be of different types. For example, water-based polyurethane and oil-based polyurethane are two different types. They might have different reactions to shellac. Let’s see whether you can put these polyurethanes over shellac or not.
Water-based polyurethane over shellac:
You can put water-based polyurethane over shellac. Generally, shellac is one of the most compatible coatings. They can easily go over or under other coatings. For example, you can put a clear coat over or under shellac.
That’s why you can also use polyurethane over shellac. Polyurethane will also stick to the shellac surface. Generally, polyurethane is a clear coat that provides extra protection to a surface.
So, when you will apply water-based polyurethane over shellac, it will also provide protection to the shellac surface. But shellac is also a great coating that doesn’t need a clear coat compulsorily.
Still, you can add additional water-based polyurethane over it. It will keep the shellac safe from weather effects and it will also be easy to clean the shellac surface. Moreover, polyurethane will give a shiny look to the surface.
But you have to cure the shellac surface to put polyurethane over it.
Oil-based polyurethane over shellac:
Oil-based polyurethane is another type of polyurethane that uses different petroleum and mineral solvents. You can also use oil-based polyurethane over shellac. Generally, oil-based polyurethane is better for using on shellac.
It will be more compatible with shellac. Besides, shellac is compatible to remain safe under polyurethane. But you must apply polyurethane over a fully cured shellac surface.
For example, if you have applied shellac newly, you have to leave the surface for curing. Then you can apply the oil-based polyurethane. Otherwise, the polyurethane will not adhere to the shellac surface.
So, you must need surface preparation before applying the oil-based polyurethane.
Generally, shellac can stick to almost any surface. So, if you put polyurethane over it, it might stick to the shellac. But you have to try to make the coating durable.
However, you might have heard about waxed and dewaxed shellac. You can put polyurethane over any of these types of shellac. They are both compatible with polyurethane.
Moreover, polyurethane will make the overall surface durable and long-lasting. Besides, you will get a glossy and attractive surface over shellac.
Will polyurethane stick to shellac?
Yes, polyurethane will stick to shellac. Generally, shellac is an excellent coating that is compatible with most surfaces. So, it will also stick to the polyurethane coating.
But when you put polyurethane, you will expect the coating will be durable. So, you have to ensure that the shellac surface has been cured completely. Otherwise, the polyurethane coating will not be long-lasting.
Generally, polyurethane can be water or oil-based. Both of these polyurethane coatings will stick to shellac. Shellac is pretty well to go under or over polyurethane. So, whether you put polyurethane over shellac or under shellac, it will stick to the shellac surface well.
How to apply polyurethane over shellac?
Now that you know you can apply polyurethane over shellac, you might want to know how you can apply it appropriately. Because if you put polyurethane in an inappropriate way, the coating might not be durable. So, let’s see how you can apply polyurethane over shellac properly.
Preparing the surface:
Generally, you have to prepare the surface before coating it with any material. So, you have to clean the surface. Moreover, you have to sand the surface so that the shellac can stick to the surface well.
Then you have to apply shellac. You can apply shellac with a brush and let it dry. After drying the shellac, you can apply one or more layers of shellac.
Drying and curing:
You have to dry and cure the shellac surface well before applying polyurethane. Otherwise, the polyurethane will not be long-lasting over the shellac surface.
Preparing the shellac surface:
After applying and drying the shellac, you have to prepare the surface for applying polyurethane. For example, you can use a fine grade grit to sand the shellac surface. Though shellac is compatible with polyurethane, sanding the surface will ensure to stick both surfaces.
Finally, you can apply polyurethane. You can apply a thin coat first and let it dry for at least 4 hours. Then you can apply another layer. But make sure that the previous layer is cured and dried well.
Allow 3 to 4 days to cure the polyurethane completely before using the final element.
Is shellac water-based or oil-based?
Shellac can be both water-based and oil-based. Generally, whether shellac is water-based or oil-based depends on the sources the shellac has come from. Some water-based shellac is used to coat over water-based paint.
On the other hand, oil-based shellac is used over oil-based paint. But most commonly, water-based shellac is vastly used over different surfaces.
Is shellac the same as polyurethane?
No, shellac is not the same as polyurethane. Generally, shellac is a natural element. But polyurethane is a synthetic material that is made of polymeric materials.
That’s why shellac has less volatile compounds than polyurethane. Moreover, you can apply polyurethane and shellac over each other. So, both of them are pretty compatible. But they are not the same.
Can you paint shellac over polyurethane?
Yes, you can paint shellac over polyurethane. Shellac is compatible with most surfaces. So, it will also stick to the polyurethane surface.
Generally, we use polyurethane as a clear coat or final coat over a surface. If you want to put shellac over polyurethane, you can do it. But you have to ensure that the polyurethane surface is cured completely before applying shellac over it.
What finish can you put over shellac?
Now that you know shellac is compatible with most surfaces, you might want to know what finish you can put over shellac. Here is a list of finishes that you can apply over shellac.
Polyurethane is a common clear coat that you can apply over shellac. You will not need much preparation and the process is pretty easy. But you have to cure the shellac well before applying polyurethane.
Moreover, polyurethane will make a hard surface finish that will protect shellac. Besides, a polyurethane clear coat will make the surface look shiny and attractive.
Oil-based varnish is also suitable to put over shellac. Generally, shellac is compatible with varnish. So, the varnish will not react with shellac. Moreover, it will be safe to apply oil-based varnish over shellac.
Whether the shellac is waxed or not, the varnish will stick to the surface. Moreover, the varnish will dry fast and make a protective shiny layer over shellac.
You can also use lacquer over shellac. Generally, the lacquer will work well over the shellac surface. Moreover, it will not affect the shellac surface badly. So, using lacquer is pretty safe over shellac.
Besides, the lacquer will provide a durable and glossy surface over shellac.
Polyurethane sticks to the shellac surface. So, you can put polyurethane over a dewaxed or waxed surface. Polyurethane is not compulsory to put over shellac since shellac is also an excellent sealant. But if you want to make the surface thick and durable, you can put polyurethane over shellac.