As outdoor furniture, fencing and other outdoor wooden items are often a large investment that you want to last for a long time, they should be treated regularly. However, it can often be hard to determine what is the best thing to use amongst the many varieties of wood finishes available.
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Varnish
Good for: outdoor furniture and decking
Varnishes are usually resin based, and they dry to form a hard film that coats the wood’s surface. They are one of the most durable types of wood finish, as the coat they provide is resistant to water and scratches.
This is ideal for external use as it has a high resistance to UV light and moisture. It can be used on previously stained and treated wood to help protect against the effects of weathering, such as cracking and peeling.
Varnish is available in a range of finishes and enhances the natural grain of the wood. It normally dries clear, but certain varnishes may have a slightly orange or yellow tint to them.
To achieve the best finish, any cracks in the target surface should be sanded back and filled in prior to application. You should also be cautious while the varnish is drying, as this can take a long time and make the surface more susceptible to dust or dirt.
Paint
Good for: fences, doors, decking and furniture
Wood paint is one of the easiest ways to quickly transform a surface and is available in a range of colours. Paint offers the wood protection from fading, peeling and other damage that can be caused by the weather.
It looks best when several coats are applied with a brush, and be careful to select a paint that is pet and child safe once it has dried. It can also be applied with a roller or paint sprayer, and is good at hiding any flaws that may be present in the wood.
However, it is a much more permanent option compared to other finishes, as it is extremely difficult to remove. You may additionally experience peeling or bubbling within the paint, which means that it may need regular maintenance.
Preserver
Good for: fencing and sheds
This works similarly to stains and oils by protecting the wood from rotting and decaying, in addition to waterproofing it. It also gives resistance to mould and woodworm, with UV protection shielding from fading or greying of the wood. For the best results, apply generously with a brush so that the timber is soaked.
Stain
Good for: decking and fencing
As well as providing hardwearing protection from weathering, stain enhances the appearance of the wood grain. It is resistant to cracking, blistering and peeling, with some brands offering a non slip finish that is ideal for decking.
Stain can either be a penetrating or surface stain, and is ideal for applying before using a different finish coat over it for maximum protection. However, it should only be applied to bare wood.
Oil
Good for: decking and garden furniture
Wood oils penetrate the wood grain to replace oil lost through the effects of weathering and seal the surface to protect it from the inside out. It helps to prevent drying and warping through its tough, waterproof finish. Oil is best applied in thin coats with a brush, and allow each coat to dry before reapplication. There are several different types of oil that are available to use on wood:
- Tung Oil – this is derived from the seed of the Tung tree that is native to China, so it may also be labelled as Chinese Wood Oil. It is environmentally friendly and non-toxic before and after applying, as well as being non-darkening to the wood. This oil dries clear and does not turn yellow as much as other finishes over time. However, it can be hard to find a 100% pure version of this oil, it is expensive and has a long drying time.
- Linseed Oil – this natural oil is derived from flaxseed, so it may also be called Flaxseed oil in some places. It is very versatile as it can be used alone or alongside other finishes including varnish, stain and paint. However, to get the most out of this finish, it should be applied onto bare wood or wood that has only been treated with other oils, or it will not penetrate the surface properly. It is also very flammable, so anything soaked in this oil should be disposed of carefully.
- Danish Oil – this is made by mixing a natural oil (Tung or Linseed) with varnish and thinner to provide the benefits of oil with the protection and durability of varnish. Similarly to other oils, it is best applied only to bare or previously oiled wood.
- Cedar Oil – derived from cedarwood trees, this can prolong the life of wooden furniture and has the added bonus of being a natural insect repellent.
Lacquer
Good for: outdoor furniture
This is normally made by mixing together various solvents and resins, although it was originally made from the secretions of the lac bug. Despite being thin, lacquer will usually dry hard and provide a durable finish if applied with the right amount of skill.
However, lacquer contains a high amount of volatile organic compounds (VOCs) that are released during application, meaning that it is not very environmentally friendly.
Polyurethane
Good for: exterior doors, windows, fences and outdoor furniture
This is a hardwearing and water resistant finish, that dries hard. There are two different types of this finish, oil based and water based. Oil based has a warmer look, but can yellow over time, whereas water based dries and remains clear.
They can both provide protection for a few years if they are applied and maintained correctly. Polyurethane is also scratch and stain resistant, but can be challenging to repair if it becomes damaged.
Shellac
Good for: using as a primer coat or spot priming outdoors
Shellac consists of an alcohol solvent mixed with the secretions of the lac bug, which dries as a glossy, hard coat. It offers a durable finish as well as protection against abrasive or water damage. It is good to use on dining surfaces, as it is non-toxic and food safe.
However, care should be taken to avoid exposure to heat from mugs or plates by using coasters, and alcohol spillages should be avoided as much as possible.
Before using any wood finish, it is best to research which one you have the right equipment and skill level for. Ensure you correctly prepare the target surface before beginning and check the weather conditions so that there is not a risk of the finish adhering improperly.
You should also check if you have an outdoor suitable version of whatever finish you are using, as finishes designed for indoor use will not be able to withstand the conditions of your garden.
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