Maybe you’re looking for a higher sheen level for your wooden furniture. Or maybe you want a higher resistance to physical and chemical damage for your highly used cabinets. Then applying a lacquer finish over your existing varnish might just be the solution you’re looking for.
This article will cover applying lacquer over varnish and some things to remember. But first, let’s have a brief introduction of the two finishes.
What is Varnish?
Varnish is a topcoat that you can use on wood furniture and porches. It’s either clear or tinted. The clear version shows the wood’s natural color, while the colored versions act as stains and change the wood to a specific color. Spar varnish is used on outdoor furniture and wooden objects in contact with water, such as boats, decks, and beach chairs. It produces a glossy finish, is transparent, and hardens when dry to offer protection against abrasions and UV light.
Because of its high solid-to-liquid ratio, the varnish is durable and can last up to ten years if you maintain it properly. Varnish sits on top of the wood, unlike other finishes that penetrate the wood surface. This is why it’s able to offer protection against moisture and why you can use it to come up with a glazed finish on the wood stain.
The main ingredients of varnish are solvents, resins, and oil driers. It has a viscous flow because of the high solid ratio. Varnish cures to dry via a crosslinking chemical reaction that takes place in the presence of oxygen molecules.
Uses of Varnish:
- To create a durable wood surface.
- To form a glazed finish with wood stains.
- To protect the wood from physical damage such as scratches and abrasions.
- You can use it as a top coat for base paints and stains.
- You can use it over other wood finishes.
What is Lacquer?
Lacquer is a finish made up of shellac dissolved in alcohol to create a synthetic coating on a wooden surface. It dries quickly to a highly glossy surface due to the presence of solvents and plasticizers. Like varnish, it’s also resistant to damage but wears out with time and discolors a lot quicker. Moisture compounds such as plasticizers also make it moisture resistant. It has a thin flow and can even be applied without thinning. Lacquer forms a thin film after spraying to create a smoothie finish.
There are two types of lacquer based on how they dry. One type dries through solvent evaporation–the water in the solution evaporates, leaving the solid behind. You can find this type in big box home improvement stores. The other type dries by chemical reaction and is referred to as catalyzed lacquer. They usually have a short shelf life. These are available at specialty paint shops.
Uses of Lacquer:
- It’s suitable for large furniture since its application by spraying is easier on large surfaces.
- You can use it to produce a glossy sheen.
- You can use it to protect stained wood.
- Use it to bring out the natural grain of the wood.
Can You Apply Lacquer over Varnish?
Applying lacquer over varnish depends on their compatibility. Some varnishes are compatible with lacquer, while others are not. This is because the varnish doesn’t bond well with the lacquer and peels off over time. The nitrocellulose in the lacquer may also dissolve an incompatible varnish underneath it, leading to messy paintwork.
Before applying lacquer, try to find their compatibility with the varnish from your local supplier. Most alkyd varnishes are compatible with lacquer, while polyurethane varnishes are not. Alkyd varnishes have polyester resin that adheres better to lacquer. They have a natural appearance and won’t yellow with time.
Tips to Remember When Applying lacquer over varnish
- If you’re unsure whether your lacquer is compatible with the available varnish, a safe bet would be to use a shellac coating over the varnish before you apply the lacquer on top. The shellac acts as a sealer coat, preventing the lacquer from damaging the varnish.
- It would help if you also use a test strip to determine whether the varnish will be compatible with lacquer. If the lacquer doesn’t damage the varnish on the test strip, then you can safely paint the lacquer over the varnish.
- Ensure your varnish cures completely before applying the lacquer finish over it. This will decrease the chances of solvents in the lacquer eating away the varnish.
- Before applying lacquer, examine the surface for any blemishes or imperfections such as scratches and cracks and try to fix them to prevent buildup.
How to Apply Varnish
You can apply varnish over bare wood or an already painted surface. To remove old finishes, you can use a paintbrush to apply a paint stripping solution on the wood and scrap it off with a putty knife. Also, you can remove old finishes by sanding or using a paint thinner.
Steps to Applying Varnish:
- Sand the wood along the grain direction using 180-220 grit sandpaper. This is to remove any existing finish residue or smoothen the wooden surface.
- Remove dust or dirt on the wooden surface with a damp cloth or vacuum. You can also use a tack cloth to wipe the dust residues.
- Use a grain filler to fill open-grained woods like oaks. It also smoothens the surface. Based on your preferences, the grain filler can match the wood, the stain you want to apply, or a contrast to the stain color.
- Prepare the varnish by thinning it. Oil-based varnishes are thinned by adding paint thinner in the ratio of 1:1. Acrylic varnishes, on the other hand, are thinned with water. Varnish that you buy in spray cans doesn’t need to be thinned.
- Apply the thinned varnish using a foam roller or paintbrush. Apply in long and even strokes and along the wood grain. If you’re using a spray can spray light and uniform coats at a distance of about 8 inches from the wood’s surface. Wait for 24hrs for the first coat to dry.
- Buff the surface of the first coat to smooth it out, and use a tack cloth or clean rag to wipe.
- Apply 2-3 coats more coats of varnish. Ensure you sand along the grain with 320 0r 400 grit sandpaper and wipe off the surface between coats. Wait for 48hrs before you apply the final coat.
- Apply the final coat and wait for it to cure. Curing time ranges from 1-30 days, depending on the varnish you use.
How to Apply Lacquer over Varnish
The application of lacquer by spraying is a lot more efficient than brushing. One can use either a spray gun or an aerosol spray can. The aerosol can is not suitable for large surfaces since it dries quickly. Spray guns can be in the form of:
- High volume, low pressure (HVLP gun)
- Air-assisted airless sprayers
- Suction feed guns
- Gravity feed guns
- Pressured guns.
Steps to Applying Lacquer:
- Prepare your lacquer by adding the recommended ratio of thinner. Colored lacquer, for example, has a lacquer to a thinner ratio of 1:1, while clear ones need less thinning.
- Ensure the previously applied varnish has completely dried before you apply the lacquer. You can use shellac as a sealer coat.
- Feather sand the wooden surface to eliminate available imperfections.
- Spray the first coat thinly and evenly. Ensure you maintain a uniform distance between the sprayer and the wooden surface throughout the spraying. Overlap each spray pass by 50%. The surface may start to appear blotchy, but it’ll clear when applying successive coats.
- Apply 3-4 other coats by spraying evenly from end to end and prevent buildup on the edges.
- Sand between coats using 320-grit sandpaper or a 0000 steel wool, then wipe using a tack cloth.
- Apply the last coat and buff with a 400-grit sandpaper soaked in mineral spirit, then buff with a 0000 steel wool.
Can Lacquer Finish be Repaired?
Another reason to use a lacquer finish over varnish is its ease of repair. Just like shellac lacquer is easily repairable, it’s suitable for repairs such as scratches, scuffs, water rings, and hazing because of moisture. Lacquer also yellows and fades with time hence needs a retouch. All you have to do is reintroduce a coat of lacquer on the surface you need to repair.
You can use a paintbrush to put lacquer on the damaged surface. Spray can lacquers are also available for touch-up jobs. Ensure that the color of your new lacquer matches your old or damaged lacquer. The solvent in the lacquer softens the damaged lacquer, leading to the blending of the two coats.
The solvent evaporates, and the lacquer hardens, forming a new finish on the area. This won’t work if the damage is beyond the finish level. Instead, that requires stripping the lacquer and fixing the damage before you reapply the lacquer finish.
There you go. Applying lacquer over varnish and things to remember when applying lacquer over varnish. The most important thing is to ensure the lacquer you purchase is compatible with your existing varnish. Try to test your lacquer over varnish on a test strip to capture any hurdles that might arise.
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