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How to use wood varnish

Close-up of varnish dripping from paint brush


For thousands of years, varnish has been a popular choice for waterproofing outdoor wood furniture. The first mentions of varnishes described a mix of solvent and resin and were applied by a brush. Many ancient cultures used natural resins and oils to protect and beautify wood surfaces, including the Egyptians and Greeks. The development of furniture varnish continued through the Middle Ages and the Renaissance right up to the modern day.

Exterior wood varnish is still an incredibly popular way of weatherproofing fences and furniture. Does it still stand up as an effective way to protect your garden furniture or is there a better way?

What is varnish?

Varnish is usually made from 3 main components:

  • Oil
  • Resin
  • Solvent

Varying the type and amount of each component will result in varnishes with differing properties. For example, the choice of oil will impact the colour of the finish. Resin adds strength to the finished product and can also impact colour.

Finally, solvents help thin oil and resin for workability and use. The more solvent in the mixture, the thinner the resulting varnish will be to apply. Once applied, the solvent evaporates – leaving the resin and oil to cure into a hard layer.

Types of varnish

There are various types of varnish available, including traditional and modern formulations. Common types include:

  • Acrylic varnish. Used for a variety of different applications, acrylic varnish tends to be water-based rather than solvent-based. It is usually clear and is relatively cheap when compared to other types. It is sensitive to extreme weather and may crack in high and low temperatures.
  • Polyurethane Varnish: This type is a synthetic, durable and widely used option. It is resistant to corrosive materials but is very vulnerable to UV radiation from the sun’s rays.
  • Yacht (or Spar) Varnish: Specifically designed for outdoor use and usually made from spar urethane, yacht varnish contains additional additives that enhance its ability to withstand weathering. It offers better moisture resistance but still requires regular maintenance. It is designed for protection, with little consideration for the final finish. Because it is intended for use on wood in contact with water, the finish tends to be brittle – not ideal for the garden.
  • Spirit Varnish: Spirit varnishes use alcohol as the solvent. These types are smelly to work with, contain high levels of VOC and are not resilient to weathering.
  • Alkyd Varnish: Contains alkyd resin. It has high levels of water resistance but takes a relatively long time to dry. Very pungent to apply.

How to apply traditional wood varnish

  • Sand the wood surface to ensure smoothness and remove any previous coatings. Traditional wood varnish is brushed or sprayed onto the wood. 
  • Multiple coats are typically applied to build up a protective layer. Allow to dry between coats.
  • Sand and polish to achieve the desired finish.

Drawbacks of varnish finishes

Cracked varnish on an old chest of drawers
Vulnerable varnish
Varnish can crack over time, letting in moisture and UV radiation from the sun.

Flexibility and Durability

Varnish coatings tend to become brittle over time and changing weather conditions, leading to cracking and peeling when exposed to wood movement caused by temperature and humidity changes.

Roxil Wood Protection Cream remains flexible, adapting to the natural expansion and contraction of wood. This flexibility ensures long-lasting protection without the risk of surface damage or failure.

Lack of breathability

One of the significant drawbacks of varnish is its lack of breathability. Varnish forms a film on the surface of the wood, preventing the wood from naturally exchanging moisture with the environment. This can lead to trapped moisture and subsequent wood decay. Roxil Wood Protection Cream allows the wood to breathe. It forms a water-repellent barrier that enables the passage of water vapour and reduces the risk of rot and mould growth. 

UV Resistance

UV rays from the sun can cause wood to fade, discolour, and degrade over time. Varnish offers limited UV protection and may require additional UV-resistant topcoats. Roxil Wood Protection Cream, on the other hand, contains advanced UV stabilizers that help shield the wood from harmful sun radiation. This ensures that the natural beauty of the wood is preserved for an extended period.

Water Repellency

While varnish provides some water resistance, Roxil Wood Protection Cream excels at waterproofing. It forms a hydrophobic barrier that repels water, preventing damage like warping, swelling and splitting. The superior water repellency of Roxil makes it highly effective at protecting garden wood exposed to rain, snow, and other outdoor elements.

What are VOCs?

Volatile Organic Compounds (VOCs) are the reason why treatments of all kinds give off a powerful smell. They can be dangerous to human health and the environment and can be found in a wide range of DIY materials.

VOCs can produce ground layer ozone, which is the main cause of smogs in cities. They are also irritants and can cause cold-like symptoms in people sensitive to them. As well as varnishes, VOCs are also present in paints and adhesives. 

Despite its widespread use, varnish has several limitations when it comes to waterproofing outdoor wood furniture:

  • Maintenance Intensive: Varnish coatings require regular upkeep to maintain their effectiveness. Exposure to sunlight, moisture, and changing weather conditions causes varnish to degrade over time. 
  • Brittle and Prone to Peeling: Varnish is not flexible and can become brittle as it ages. This rigidity makes it susceptible to cracking and peeling, especially when exposed to expansion and contraction due to temperature and humidity changes. Once the varnish layer has cracked, it can let water in and compromise the entire structure.
  • Limited UV Protection: While some varnish may provide some level of UV resistance, it is not as effective as modern alternatives like UV-resistant wood stains or protective coatings.
  • Environmental Concerns: Traditional varnishes often contain volatile organic compounds (VOCs) and other potentially harmful chemicals. This can pose health risks during application and contribute to environmental pollution as well as being unpleasant to work with.

While varnish has been used for centuries to waterproof outdoor wood furniture, modern alternatives like silicone-based wood creams provide superior protection, durability, and ease of use for waterproofing outdoor wood.

Finish outdoor wood with Roxil Wood Protection Cream

Varnish typically requires multiple coats and meticulous surface preparation, including sanding and polishing. Roxil Wood Protection Cream is easy to apply and requires minimal preparation. It can be applied directly to the wood surface using a brush or saving both time and effort. Roxil Wood Protection Liquid can be applied with a pump-action pressure sprayer too.

Roxil Wood Protection Cream is water-based and low in VOCs, making it a more environmentally friendly choice than VOC-heavy varnishes. It minimizes the release of harmful substances and ensures safer application and long-term use.

A silicone cream emulsion, Roxil Wood Protection Cream for the long-term protection of exterior wood furniture, fences and more. for 10+ years. It protects wood from moisture damage, weathering, warping and moss/algae growth. It also slows tannin-leaching and helps wood maintain its colour for longer.

Once applied by brush or roller, the colourless cream formula absorbs into wood to create a waterproof barrier. It will protect fences, decking, sheds, furniture and more from the elements without changing their appearance.

For more information call
01403 210204