Let’s face it. Paints help to achieve an attractive finish but the finish is not as durable as varnish. So can you put varnish over paint to improve durability?
You can put varnish over paint but to make the varnish stick well, you’ll need to sand the paint with a fine-grit sandpaper. This is to create pores in the paint that the varnish can seep into to stick properly.
A coat or two of varnish over paint helps to protect the paint from scratches, dents, and moisture. Painters commonly use varnish over paint as a sealant.
Painters generally agree that water-based varnish is the best to use over paint. This is because water-based varnish is less toxic and it enhances paint color.
What Happens If You Put Varnish Over Paint?
If you put varnish over paint, a few things happen. First, the varnish enhances the color of the paint.
Depending on the shade of the paint and the type of varnish, the varnish can either make the paint color appear darker or lighter. Secondly, the varnish will help to protect the paint from damaging factors like moisture, scratches, and dents.
You should know that varnish generally works better when used over water-based paint. This is because water-based paints have no gloss or hard layer that can prevent the varnish from sticking.
Also, water-based paints accept both water-based and oil-based varnishes. If you put varnish over water-based paint, all you need is for the water-based paint to be clean and grease-free. Oil-based paints on the other hand are a different story.
To put varnish over oil-based paint, you’ll need to sand the paint first. This is because oil-based paints have a natural sheen that will prevent the varnish from sticking. So, you need to sand off the glossy sheen to put varnish over the paint.
When Should You Sand Paint Before Varnish?
You don’t have to sand paint before varnish. You should only sand paint before varnish if the paint will prevent the varnish from sticking properly. Here are cases when you have to sand paint before varnish:
If the Paint Is Oil-based – Oil-based paints generally have a natural glossy layer that prevents the varnish from sticking properly. So before you put varnish over oil-based paint, you need to sand the top glossy layer off to make the varnish stick.
If the Paint Was Sealed – If the paint was sealed with a top coat or sealant, you’ll have to sand the paint before putting varnish over it. This is to remove the sealant. If the sealant is left on the paint, it will prevent the varnish from sticking. You should know that it’s usually advised to strip sealed paints before varnish.
If the Paint is Peeling – If the paint is peeling off, it’s usually best to sand the paint off. If you leave the peeling paint and varnish over it, the spikes of the peeling paint will cause bubbles and paint pimples in the varnish as it dries. Peeling paint can also cause bleed-through.
If the Paint is Bumpy – If the paint is bumpy, the bumps will make the varnish uneven when it dries. So you need to sand the bumps and smoothen the surface for the varnish to come out smooth.
When You Shouldn’t Sand Paint Before Varnish?
Now, let’s check out when you don’t have to sand paint before varnish:
When the Paint is Water-based – Water-based paints don’t have a glossy layer that will prevent the varnish from sticking so you don’t need to sand the water-based paint. All you need in this case is to ensure that the water-based paint is clean and grease-free.
When the Paint is Perfect – For the paint to be perfect, it must be dirt-free, grease-free, smooth, and should have no top coat. If the paint meets all these criteria, then you can varnish it without sanding first.
When Dealing With Fresh Paint – If the paint is still new or was recently applied, then you don’t have to sand it because the paint is still in perfect condition.
Now that you know when to and when not to sand paint before varnish, let’s check out how to apply varnish over paint.
Related Read: Can You Varnish Over Old Varnish?
How To Apply Varnish Over Paint? (5 Simple Steps)
Applying varnish over paint isn’t difficult as long as you follow the right steps. This guide will show you how to do that correctly but first, we need a few tools and supplies:
- Fine-grit sandpaper
- Clean rags
- Dish soap
- Wire brush
- A paint shield
- Varnish Primer (optional)
Here is a 5-step guide on how to varnish over paint:
1. Find Out The Type of Paint
The first step is to figure out what type of paint you are dealing with. The type of paint determines how to prep it for varnish. To know the type of paint, use a clean rag soaked in alcohol to wipe a spot in the paint.
If the paint comes off, it means the paint is water-based. If it doesn’t come off, it’s either oil-based or a sealed finish; both of which you have to prep the same way for varnish.
You can also figure out the type of paint by feeling the paint. Oil-based and sealed paints often have a glossy and sleek feel while water-based paints feel textured and dry.
2. Sand The Paint
The next step is to sand the paint. This step is necessary regardless of the type of paint. For water-based paints, you can sand with fine-grit sandpaper to create pores in the paint that the varnish can soak into.
If the paint is oil-based or sealed, then you should start sanding with medium-grit sandpaper. This is to remove the top layer of the paint. After, you can finish off with fine-grit sandpaper.
After sanding, there is sure to be dust and paint residue on the surface. You need to remove these with a clean rag as they can ruin the finish if left on the paint. Wipe the surface clean before the next step.
3. Prime The Surface (Optional)
The step is solely for surfaces where you removed or stripped paint. Such surfaces will be uneven and rough. Not to mention the marks and paint residue that will be on the surface too.
In other words, this step is usually for when varnishing over oil-based paints. For water-based paints, you don’t need to prime. To prime for varnish, you need a special primer designed for varnish.
A coat of the primer or build-up coat is enough. Too many coats and the varnish will not stick well.
4. Apply The Varnish
You can apply varnish using a roller, paintbrush, or spray gun depending on which you are comfortable using. You can thin the varnish before applying it so you get good coverage. To thin the varnish, use water for water-based varnish and mineral spirits for oil-based varnish.
Ensure to allow enough dry time between coats of the varnish to prevent getting a muddled-up finish. You can apply up to 4 coats of varnish but you should know that the more coats you add, the glossier the finish will be. Allow the varnish to dry for at least 3 days before using it.
So what does varnish do to paint color? Let’s find out.
Does Varnish Change Paint Color?
Varnish doesn’t change paint color the way you think. A coat of varnish over your paint will enhance the paint color making the color appear deeper or lighter than it really is. Either the paint color gets deeper or lighter depends on the type of varnish and the number of coats.
Water-based varnish for instance is known to make paint color appear vibrant. Water-based varnish is clear and allows light to pass through making the paint color appear brighter.
Oil-based varnish tends to make paint color appear deeper. Given the high oil content of the oil-based varnish, it only allows low light to pass through meaning that the paint color will reflect low light making the paint darker or deeper.
The number of coats also matter. For varnish, the more coats you add, the glossier the finish gets. You should also know that varnish tends to develop a tint after a few years.
Water-based varnish begins to appear deeper due to the accumulation of dirt and filth on the finish. Oil-based varnish turns yellowish or amber-like due to the high level of oils in the varnish. Organic varnish also turns darker as time passes.
Types of Paints You Can Varnish Over:
You can varnish over most paints, here are some of them (except gloss paint):
You can varnish over latex paint easily. All you need to do is to ensure that the latex paint is clean and properly sanded. As long as the latex paint is clean and sanded, it will accept any type of varnish.
You can put varnish over chalk paint because chalk paint contains little to no chemicals that can repel varnish. Also, chalk paint is water-based meaning that it dries fast and will accept any type of varnish.
The best part is you don’t even need to sand the chalk paint before putting varnish over it. This is because chalk has no glossy film that can prevent the varnish from sticking.
You can varnish over emulsion paint. But, it’s better to apply water-based varnish over emulsion paint because most emulsion paints contain a high volume of water as the paint thinner. So the paint might not be compatible with oil-based paints.
You should also know that the type of emulsion finish determines how you’ll prep it for varnish. For instance, a high gloss emulsion finish will need sanding while satin and matte finishes don’t need sanding.
You can varnish over acrylic paint as long as the paint doesn’t have a top coat. If the paint has a top coat, you need to remove it to put varnish over it. Acrylic paints will benefit from having a varnish top coat because the top coat will protect the acrylic paint from dents, scratches, and moisture.
You can varnish over white paint but the finish will look boring. This is because white paint is a neutral color so the varnish will only enhance the white paint making it look whiter or brighter. Putting varnish over white paint will reveal a durable but boring finish. I’ll advise tinting the varnish to reveal some color.
You can apply varnish over satinwood paint but you’ll need to do some sanding to allow the varnish to stick. This is because satinwood paint is a tough and semi-gloss finish that will prevent the varnish from sticking if you don’t sand.
You should also know that satinwood paint doesn’t need a sealant. Some painters even see satinwood paint as a final coat and use it over base coats. So without varnish, satinwood paint is durable and colorful enough.
You can varnish over matte paint and the best part is you don’t need to sand the matte paint unless it is damaged or it was sealed with a top coat. This is because matte paints have no gloss at all.
Matte paints are usually water-based paints made with color, a binder, and water. As such, it has no chemicals that can repel varnish or a top coat that can stop the varnish from sticking. Both water-based and oil-based varnishes will work over matte paint.
Clear Varnish Over Paint
You can put clear varnish over paint but you should know that clear varnish tends to develop tints after a while.
Oil-based clear varnishes especially are known to turn yellowish. If you want a clear varnish over paint, pick water-based clear varnish as it enhances paint color better and doesn’t turn yellow.
You shouldn’t varnish over gloss paint except you remove the gloss paint. Gloss paints have a common feature. When dry, the gloss paint reveals a waterproof film that prevents varnish from sticking properly.
To paint over gloss paint, you’ll need to strip the gloss off. In most cases, you’ll have to remove the entire gloss paint to allow varnish to sit properly.
Overall, you can varnish over most types of paints. All you need to do is to ensure that the paint is clean and properly sanded before putting varnish over it.
Remember not to use varnish over oil-based paints or sealed paints without removing the gloss first. Also, water-based varnish is generally agreed to be better than oil-based varnish. After applying varnish, leave it for at least 3 days before subjecting the surface to regular use.