The Differences Between Varnish And Polyurethane

Varnish and polyurethane are two popular finishes used for furniture refinishing today.  It’s not a really a battle between varnish vs. polyurethane because one isn’t better than the other. Both have positives and negatives that I will explain in this post.

What Is Varnish?

Varnish is used on wood furniture to give it a shiny protection and gloss. It is usually transparent and has very little color. It typically becomes glossy when dry, but flatting agents can be added to give them semi-gloss or satin sheens.

Varnishes are also very durable and resistant to wear, moisture, stains, and heat. One drawback of using varnishes, though, is that each coat acts as its own. They don’t blend with each other well, so sanding the previous coat is essential in order for the next one to properly stick to it.

Varnish vs polyurethaneA benefit of varnish is that it doesn’t require a sealer. Different types of varnish have different drying times, but all of them can be sped up if they are exposed to heat. Be careful though because most varnishes are highly flammable.  Varnishes are best used on dark wood since they tend to give the wood and amber color and allow it to naturally yellow with age.

Varnish can be applied in different ways. When applying it with a brush, make sure that you don’t shake the can. Shaking the can will form bubbles in the finish, which is then transferred to the surface of your furniture when brushed on.  Also make sure not to over brush, as this may leave brush marks on the surface.

When working with outdoor furniture, spar varnishes may be your best bet. This is because spar varnish does not only protect the wood from temperature changes and UV rays but also gives it flexibility so that it could last for many years. It is also resistant to water, so furniture finished with spar varnish will be less prone to rotting.

What Is Polyurethane?

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Polyurethanes, on the other hand, leave hard and durable coats that are best used for hardwood floors. There is not much difference between polyurethane vs. varnish since polyurethane also has some of the advantages and disadvantages of varnish. Polyurethane is newer than varnish, so some old-timers may advise against using it. However, it’s so easy to use that even a beginner could apply it correctly.

The coats this type of finish produces are harder, more durable, and more resistant to water than those that are produced by other types of finishes. Like varnishes, they are available in different sheens like matte or gloss. Less coat application is needed because of the film’s build. However, these coats are easily damaged by shock or heat. Polyurethane also does a lousier job in penetrating wood than other types of finishes, but this can be remedied by using oil varnishes with it. This kind of finish dries quicker and has a better flow than varnish, so there would be less brush marks and particles on the finished surface. However, it may tend to look like plastic when it dries and it is not very easy to repair. Just like varnish, make sure that you don’t shake the polyurethane can, as this can cause bubbles to form.

Polyurethane varnish should not be used outdoors because of its sensitivity to ultraviolet light. Some use UV-absorbers in order to protect the surface from the sun’s rays but this is only good for at least 2-4 years.

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When choosing between varnish vs. polyurethane, it is important to weigh both their pros and cons. For example, varnish, more particularly spar varnish, is best for outdoor use while polyurethane is best to use on indoor furniture. Old-timers may advise against the use of polyurethane but that is just because they are resistant to change. Both these finishes are actually very effective if used on the right kinds of furniture.

9 thoughts on “The Differences Between Varnish And Polyurethane

  1. I have already used a polyurethane on my kitchen cabinets and its not as shiny as I want, can I put something else over it.

  2. Do you have information about SYNTICO CLASSIC GLOSS It is kind of oil based poliuretane , made in Sweden and available in the US/possible/

  3. hello i’m from morocco my job is varnisher decouration I may publish some photos of my work I seek someone who loves to build company here in my country and looking always for new decouration of varnish and paint of wood

  4. I have old painted wood floors and I want a heavy coat gloss and protect it from water what should I purchase?

  5. I have an old vanity and a matching dresser that I wood like to ‘spruce up’. I am told that I will need to re-varnish them. I would like to also give them a new color. There current color is a dark wood and I would like to do a wood that is lighter or has more red in it. Would I need to stain it then put on the new varnish on ( after it is sanded) or can varnish have color in it?

  6. After taking it down to raw wood, sanded and dust free, you may use a stain with a varnish or poly/varathane over it for protection. There are varathanes and ploys that have stain in them. I tried one once and did not like the staining consisting during application – the project came out “blotch”. That was twenty years ago so there might be better products not. Do a test first.

  7. Is it possible to mix a small amount of varnish with ‘fine art’ oil paint so as to thin the paint substantially??

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