Regardless of what new products and technologies become available, timber’s natural look, cost and durability mean it will remain a popular building material. Whether it is being used indoors for floors or for outdoor purposes such as decking or fencing, any exposed timber needs to be treated and coated to protect it. There are a seemingly endless range of coatings available, and to know which one is right depends on what type of timber is being used and what it will be used for.
All timber will need to be protected from insects and mould and sealed to keep moisture out to protect against rotting and warping. Timber will also need to be guarded against basic wear and tear, especially in uses such as flooring where there is a high level of contact. Also, any timber which is used outside will need to be guarded against increased exposure to the elements such as wind, rain and UV light.
Different finishes will provide different levels of protection and different types of timber will require different products. There are also several levels of environmentally friendliness, and price is also a factor. But for many, the biggest issue will be the appearance of the final product, and the potential range is huge.
The first thing to look at when selecting a coating is whether it is the first application or a reapplication. Colin Watson, director of coatings consultancy company Sandbind, says if the performance of the previous coating was acceptable, then “overcoating with the same system is generally sound advice”. He says that if a change of products is made, the timber will need to be sanded back and washed to remove any traces of the materials present in the previous coating, as they may not always be compatible.
Timber washing products are available in all major brands and will remove most previous finishes as well as other organic stains such as grass and grease. After this the timber should be ready for the new application. If the timber is starting to look lifeless a coat of a revitalising product such as Intergrain Reviva will clean and prepare the timber and help restore some of the original look.
Whether the timber is inside or outside will dictate what range of products are available to choose from. For exterior use, products contain pigmented UV absorbers based on zinc or titanium which prevent bleaching of lignins from wood over time. Traditionally, solvent based products have been better suited to UV absorption, although some much better water based products are now entering the market. For use on areas such as decks, Watson recommends the timber be allowed to weather for four to six weeks to let some of the excess tannins to drain out before washing and coating and for better penetration of oils.
For durable interior finishes such as floors, one of the most important aspects is a hard wearing finish which will withstand high foot traffic. Solvent based polyurethane is one of the most common products used on floors. It can provide a clear glossy finish and form a hard protective layer which keeps out moisture and protects the wood. Tung oil is also suitable for floors — it provides a less glossy, clear matte finish with a slight golden tint. It penetrates into the wood to nourish and preserve it and the final result is almost completely impervious to water. Tung oil finishes are also available in most brands. They have a similar effect but may not necessarily contain any actual tung oil.
In most cases there will be an option of water or oil based finishes. Oil based products work by penetrating into the wood to preserve it, as well as forming a hardened water resistant coating. Water based products form a hard protective film over the top of the wood. Oil or solvent based products are not as easy to clean up and can be less environmentally friendly. They can contain volatile organic compounds (VOCs), which means it is vital to ensure adequate ventilation during application.
Water based products can be quick to dry and longer lasting. If not properly applied there can be the potential for cracking, which can result in moisture trapped under the protective layer and accelerate the decomposition of the wood.
Watson says the type of wood is also a factor in coatings. “Some timbers are very oily and contain sugars and exudates that can affect the adhesion of some systems. Water based coatings, while becoming very popular, do require the correct priming system on these particular hardwoods. It is important to follow the manufacturer’s recommendations in this regard.” All timber will need to be protected against fungus and insects and most products available provide adequate protection on their own.
Lisa Madigan, marketing manager from Orica Woodcare, says Orica have three brands that cover all bases. “Cabot’s is suitable for DIY projects. It contains a range of finishes and is simple to use. Because they’re water based they dry faster and are easier to clean up. Feast Watson is a bigger range of more specialist products, including many which are suited to timber flooring. Intergrain is top of the line for people who are prepared to pay for the best, as well as being more environmentally friendly.”
There are plenty of other paint company brands that supply wood finishes, such as Wattyl, Taubmans and British Paints, and there is a push towards more natural and environmentally friendly products such as Intergrain and Organoil.
Dieter Groening, managing director of Bio Products, believes there is a demand from consumers for all natural products. He says his products are made from all-natural, non-toxic ingredients which are low allergenic. Products are also tested to ensure their performance is as good as other products in the market and they contain the lowest percentage of VOCs.
There are also products to avoid. There is some concern in Australia about the dangers of solvent-based polyurethane, which is commonly used on floors. The solvents used in its production contain toxic isocyanates and extended exposure can result in light headedness, breathing difficulties, dermatitis and emphysema.
If a solvent based polyurethane is to be used, it is recommended there is adequate ventilation during application. Possible alternatives include water based polyurethane, hardwax oils and tung oil modified polyurethane. Some brands such as Bio Products and Whittle Waxes refuse to incorporate solvent based polyurethane due to health and environmental concerns.
