Man applying varnish to a woodent fence with his daughter

Your Guide to Varnish Types and Applications

Real wood brings added value and an elegant touch to any room, but it is susceptible to damage from water, sun, and regular wear. The following guide provides an overview of the types of vanish that you can use to protect different wood surfaces. Find out how to avoid some common issues and keep the wood looking its best for a long time to come.

Effective Protection for Every Wood Surface
After you use regular stain (as opposed to a stain and sealer in one) to transform the colour of wood or to showcase its natural beauty, you should also apply a varnish topcoat. This protective finish will help the stained wood hang on to its colour and shine.
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Choices for Protective Wood Finishes

You can find a number of varnish options on the market today. Each unique choice has a different look and level of protection. Consider which type is best for your project.

Here is a quick overview of the most common wood varnish types:

  • Water-based polyurethane: Clear- and quick-drying, water-based polyurethane is a top choice for lighter woods and a great option for lowering your waiting time between coat applications. It is sometimes available in formulations with acrylic, as well as in formulations specifically for hardwood flooring. Cleaning is easy and can be done with some soap and water, and it has less of an odour when compared to oil-based varnish.
  • Oil-based polyurethane: The light amber colour of oil-based polyurethane gives it a warm and welcoming glow. It is an oil-based and hard-finish varnish that provides superior protection for hardwood floors and is typically preferred for darker woods. It requires fewer coats but a longer drying time than water-based varnish and clean-up is easily done with mineral spirits.
  • Oil-modified polyurethane: A great option for wood flooring, oil-modified polyurethane combines the warm finish of an oil-based varnish with the quick-drying properties of a water-based one. All you need for cleaning is soap and water.
  • Lacquer: Very easy to apply, lacquer is a quick-drying topcoat that provides a high-gloss and clear finish. It is not the best choice for floors as it can develop a tint over time and is susceptible to scratching, but it can be used on other wood and metal surfaces. You’ll need to have lacquer thinner on hand for cleaning.
  • Shellac: An alcohol-based and natural topcoat, shellac has a slight amber tone that isn’t typically suitable for lighter woods. It can be used on flooring but is more susceptible to scratches than polyurethane and so requires more upkeep. Because it is not very heat-resistant, shellac should not be used on surfaces where hot items will be set down. However, it does work on drywall, cured masonry, metal, and cured plaster. For cleaning, use either denatured alcohol or a water and ammonia mixture.
  • Spar urethane: An oil-based varnish, spar urethane is very resilient. It has a longer drying time, but the finish is highly durable and a great choice for protecting wood from damage caused by water, UV, and temperature changes. It is a go-to varnish for bar tops, bathroom cabinets and other surfaces that make contact with moisture, and it is also used on wood or window trim that receives sunlight. Mineral spirits are used for cleaning.
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Pro Tip

Make sure you check the manufacturer’s information to ensure that the prepping, staining, and finishing products you use are suitable for the application. For example, a surface that is used to hold food needs a food-safe varnish.
Picking a Sheen Level
Sheen is an indication of a topcoat’s shine and lustre.
Hardwood floor with a very glossy finish

High-gloss and gloss sheens are used to impart wood with a deep shine, but they can also make blemishes more apparent.

Semi-gloss sheens provide a more muted shine.

Satin sheens have a moderate shine which makes for a more natural look. They hide minor surface imperfections well.

Flat and matte finishes obscure surface imperfections even more thanks to a low shine.

More Protective and Decorative Finish Options

You can find many more finishes for enhancing and protecting wood surfaces, including tung oil and Danish oil, as well as specifically formulated finishes made for conditioning butcher blocks and cutting boards.

There are also decorative washes, wood effects, and finishes that can create burnt, crackled, weathered, and aged looks. Other finishes are a suitable replacement for stains and topcoats, can be used to turn latex paint into a glaze, or be applied to stained wood.

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Wood Care 101
Whatever your wood varnish project, from finishing a piece of furniture to restoring a hardwood floor, always make sure to follow this quick guide and have the appropriate product for the surface.
Person sanding a piece of wood with sandpaper
Surface Preparation
  1. First, test the stain in an inconspicuous location or on some wood scrap. Once dry, see how it looks in the surrounding light, as the lighting of the room will impact the final appearance. The stain opacity as well as the colour and texture of the wood can also make a difference, so it is important to know what to expect.
  2. Clean the wood.
    1. Using TSP can help ensure you won’t damage the wood surface.
    2. Use a wax strip to safely remove the wax.
  3. To aid with adhesion, use 220-grit sandpaper and sand in the grain direction. Steel wool should be avoided.
  4. Wipe away dust when finished sanding.
Person applying varnish to a wooden box using a brush
Varnish Application

Follow these steps for applying either water- or oil-based varnish to wood surfaces.

Water-Based Varnish

  1. Use a high-quality polyester brush, spray equipment, or a pad applicator.
  2. Allow 3-4 hours for the first coat to dry.
  3. Repeat to apply the second and third coats.
  4. Before applying the final coat, sand in the direction of the grain.

Note: The product will appear milky white at first but will dry clear.

Oil-Based Varnish

  1. Use a high-quality bristle brush, spray equipment, or a pad applicator.
  2. Wait 8-12 hours before another new coat.
  3. Use mineral spirits to clean tools.
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Pro Tip

Always follow safety instructions when applying varnish and ensure proper ventilation as well.
Varnish Application Problems and Causes
When applying varnish to wood, you may encounter some common problems. Make sure you correctly identify the issue before trying to fix it.
Issue
Possible Cause
Bubbling
  • Application issues:
    • Application was too thin
    • Excessive ventilation
    • Over-brushing
  • Product was stirred or shaken
Chipping, flaking, or cracking
  • Too many coats
  • Different varnish types applied over one another
Film remains tacky
  • Application is too thick
  • Applied in high humidity or cold weather
  • Incompatibility with prior coating
Visible brush strokes
  • Earlier coat didn’t fully dry before the next coat application, causing the brush to drag
Finish dries cloudy or milky
  • Product applied in cold temperature
  • Presence of moisture under the finish or the stain was not dry
  • Product was not properly stirred, and the stain agent was poorly distributed
Hi/Low spots
  • Semi-gloss or satin was not properly stirred
  • The product was absorbed at different rates on the surface
Issue
Possible Cause
Bubbling
  • Application issues:
    • Application was too thin
    • Excessive ventilation
    • Over-brushing
  • Product was stirred or shaken
Chipping, flaking, or cracking
  • Too many coats
  • Different varnish types applied over one another
Film remains tacky
  • Application is too thick
  • Applied in high humidity or cold weather
  • Incompatibility with prior coating
Visible brush strokes
  • Earlier coat didn’t fully dry before the next coat application, causing the brush to drag
Finish dries cloudy or milky
  • Product applied in cold temperature
  • Presence of moisture under the finish or the stain was not dry
  • Product was not properly stirred, and the stain agent was poorly distributed
Hi/Low spots
  • Semi-gloss or satin was not properly stirred
  • The product was absorbed at different rates on the surface
Fast and Simple Wood Repair
Over time, even wood with a protective varnish will begin to show minor damage like nicks and scratches. However, small aesthetic issues don’t mean you need to completely refinish the wood. Wood repair products like tinted wood putty, stain markers, stain pens, and filler pencils are available in most stain colours for fast and simple repairs.

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