The short answer is ‘yes.’ However, several conditions affect the result of the varnish over varnish. People usually varnish for several layers, and each layer is thin.
Yet, varnishing over varnish is different from varnishing for several layers. The difference lies in sanding the current surface before applying a new layer of varnish.
Sanding is aimed to score and prepare the surface, so the next varnish adheres well.
However, there is an opposite answer to the question: ‘can you varnish over varnish?’.
Some do not recommend this treatment, especially for woodwork pieces, because the current layer of varnish is unknown.
If the type of current varnish layer is unknown, it might cause adhesion problems because you need to clean and sand the surface properly.
Another problem is finding the right type for the new layer of varnish.
Before applying a wood varnish, as a general rule, you must completely remove any existing varnish, waxes, oils, wood stains, dust, filth, grease, uneven spots, and sticky items.
You can varnish over it if your varnish isn’t peeling and is in good condition. If you wish to change the varnish’s color, this is helpful.
If you use a contrasting hue, peeling the old varnish will assure better and more accurate color.
Types of varnish
Applying varnish over varnish should consider the new and old varnish.
Finding suitable ones is necessary because some types do not go well together. Hence can you varnish over varnish?
Yes, depending on the type. Several types of varnish could and could not be applied, and they include.
- Oil varnish: it is the slowest to dry but the most durable. It needs frequent cleaning and polishing.
- Spirit varnish: mostly called Shellac, it finishes in a translucent look that shows the timber grains. Yet it does not perform well under direct weather.
- Alkyd varnish: almost similar to acrylic, it enhances the grain and color of the wood. It shields the surface from water seepage, UV rays, and changing temperature.
- Acrylic varnish: UV protection properties are the distinguishing advantages of the varnish. Hence it is mostly used for the exterior. It gives a transparent finish but cannot be absorbed well into the wood.
- Polyurethane varnish: tough and mate perfectly describe the finishing look of polyurethane. Its durability resists tear and heat well.
Those are some popular varnishes. Based on the materials, they might be grouped into oil-based, water-based, spirit-based, and two-pack.
Steps to varnish over varnish
To avoid failure and get the desired result, here are several steps in applying varnish over varnish:
- Check the current surface. Look at every spot and figure out what kind of varnish is on the current layer, whether new or old.
- Sand and clean the surface. Ensure that there is no more dirt or dust. Wipe using a soap-solution dampened sponge and let it dry if they are needed. Use a wire brush if the peels of the current varnish appear. Clean until the surface feels smooth.
- Apply a coat of primer if the varnish cannot stick to the surface well.
- Finally, apply the varnish following the directions of the product.
Sanding before varnish
In the beginning, it is mentioned the difference between varnishing over varnish and varnishing for several layers.
The difference is in the sanding process. Hence, can you varnish over varnish without sanding the surface first? Again, it depends on the surface’s current condition and the new varnish’s quality.
If the current surface is still freshly cured, no sanding is needed. Just clean by rubbing cloth soaked in water and soap, and then wait until dry.
Yet if the surface has scratches or peeling spots, sand off a bit until all area is even and smooth.
It is impossible to recoat varnished wood without first sanding it. To begin, lightly sand the surface with 120-150 grit sandpaper or no. 2 steel wool. Clean and remove the dust from the wood.
While sanding, be aware of the layer thickness of the current varnish. Do not sand until the original layer of wood appears.
Tips on applying varnish over varnish
- Varnish will be better done when the temperature is between 20 and 25O C, and the weather is not too humid.
- The first varnish could be thinned except for the water-based one. This first layer should be focused on the grain.
- Can you varnish over varnish for many layers?Usually, people varnish over varnish for 2-3 layers. Yet you can add more until you get the desired result.
- Before applying to the real wood pieces, try on other pieces with a similar condition. Hence any failures could be minimalized.
- Check their compatibility if the new and old varnish is two different types. Water-based does not finish well to be applied over oil-based and vice versa. The safest option is the two-pack over other types, but not vice versa. Oil-based over two-pack like polyurethane does not bond at all.
Cautions of failed varnish
Varnish could fail whether it is the first or finish layer.
So, can you varnish over varnish that fails? Sure no. Applying new varnish to failed varnish will not work as the new varnish will not adhere to the previous layer.
Hence, what does a failed varnish look like? Once the usual curring time passes and the surface still look gooey and soft, it can be categorized as a fail.
Any new layers should not be applied. Depending on the varnish applied, the failed surface must be removed using mineral spirit, steel wool, lacquer thinner, or any other varnish remover.
Dark or light varnish first?
Varnish not only preserves the surface but also brightens it.
If you attempt to varnish a light color of varnish on top of an existing dark finish, you won’t notice much of a difference.
Remove the current varnish with a solvent based on petroleum to achieve the desired result of a finish with a completely different color.
When you are finished bleaching the wood, you can apply a lighter shade varnish.
People usually combine the varnish color to accentuate the depth or bring out the color. Generally, varnish could give a light or dark color.
It is more suggested to apply the dark varnish first, then the light one to finish. The light one gives a shiny effect.
Moreover, the dark varnish usually does not stick well on the light varnish. Lastly, most final colors of dark over light are not flattering.
Preparing the last varnish
Can you varnish over varnish for the finish? What’s the difference between the final layer?
The last varnish as the finish layer of the wood should not be sanded and Sanding the final layer only makes the wood look dusty and cloudy.
Only sand a layer if you want to add another layer. Improper sanding between each layer could make the final layer rough or not smooth.
If this case happens, careful wet/dry sanding can be done. Or sanding along with adding a new final layer will do.
Check the temperature and avoid flying critters or bugs during the curing process. Finally, rub out the dry steel wood to see the sheen.
Frequently asked Questions
Does vinegar remove varnish?
Vinegar’s versatility does not end with its use for stripping paint from wood.
Because the same acid that can take off paint from wood can also get into varnish and remove the chemical that makes it stick to wood, you could use it to get rid of varnish or other treatments on wood if you wanted to.
This is because the acid that enables you to remove paint from wood also allows you to remove varnish from wood.
How do you renew old varnish?
Mineral spirits can be used to carefully clean the surface, while denatured alcohol can be used to remove lacquer or varnish.
If the finish on the entire piece of furniture is worn, you need to clean the whole piece of furniture and remove all grease and grime.
The next step is to apply another layer of the finish already on the wood.
Do you need to sand between every coat of varnish?
Sanding between coats of varnish is crucial because it accomplishes two things: first, it knocks down the “high spots,” and second, and more critically, it gives teeth for the subsequent coat to adhere to.
Sanding is important because it fulfills both of these goals. If this does not occur, the successive coatings have a chance to delaminate and peel off in big sheets.
How many coats of varnish should I apply?
If you want the finish to last a very long time and be very tough, such as on a kitchen table, coffee table, or end table, etc., You should apply two to three coats of varnish to the top and only one to two coats to the legs and base.
One to two coats of finish should be sufficient for furniture such as chairs, benches, chests, and other items.
Can you put oil-based varnish over water-based varnish?
You can varnish over water-based poly with oil-based varnish as long as the first coat has fully dried, which usually takes 30 to 60 days.
To get the old finish ready for the new varnish, you’ll need to buff it with a power buffer lightly.
Because it has many volatile organic compounds(VOCs), a varnish made with oil lasts longer than a varnish made with water. Chemicals like these make the finish stronger and help it last longer.
Is yacht varnish better than outdoor varnish?
Yacht Varnish is made with Tung Oil to give boats and other outdoor woodwork the most protection and durability.
Yacht Varnish is a very long-lasting varnish made from a solvent. It was first used on boats to protect the wood and keep it from rotting over time.
If floor varnishes are applied to wood that will be exposed to the elements and requires flexibility, they may be overly rigid and prone to breaking. They may also break down in the high UV light.
If you use yacht varnish on a floor that gets a lot of use, it won’t be hard enough and will wear out faster than it should.
This product is often used to give outdoor furniture a high-gloss finish that will last a long time.
Which is better, varnish or polyurethane?
Varnish is good because it protects against UV light and is naturally durable, but it was made to be used on outdoor surfaces like a deck.
Polyurethane, on the other hand, is usually used for indoor projects like bookshelves and desks because it is flexible and long-lasting.
Both are long-lasting, come in various colors, and protect against the weather.
Can you use a sponge to apply on varnish?
You’ll need something at least as wide as your sponge.
Dip the side of your flattest sponge into the varnish and use long, even strokes to paint your surface.
For each pass, you don’t need a lot of varnish on your sponge, just enough to lightly coat the paint.