Wood is a long-standing, classical material for outdoor furniture that is making a comeback due to its warmth and traditional character. The key to longevity of outdoor wood furniture is to start with good quality pieces made with hardwood that is appropriate for outdoor use. Roble, mahogany, cornis and the less expensive acacia woods are naturally rot resistant and durable enough to withstand all kinds of weather conditions. For these wood types, special care is not necessary other than to preserve the furniture's original colour, because as it ages the wood acquires a silvery-gray tone which some customers actually prefer. Pine furniture (a softwood as opposed to the hardwoods mentioned above) is pre-treated with preservative in order to make them suitable for outdoor use, lending a durability of ten years plus. Still, it is recommended that the timber be treated annually with a good quality softwood timber preservative.
For regular cleaning, hot soapy water suffices. Scrub with a soft-bristled brush or sand lightly in the direction of the grain to remove mold, stains or mildew; more stubborn stains can be removed using timber cleaner or by sanding with a medium grit sandpaper. Avoid power-washing (pressurized water cleaning), abrasive cleaners or chlorine bleach - abrasion will result in furring.
As part of the natural weathering process, over time cracks and splits will appear in the wood, particularly on the end grain and to a lesser extent on the surface. The drier the wood, the more cracks will appear due to the evaporation of natural oils and minerals in the wood from exposure to the elements. As with most hardwoods left outdoor, this is a normal characteristic and doesn't compromise the strength or structural integrity of the product.
During winter months shelter your wooden furniture (ideally in a garage/shed) or at least keep the furniture under wraps. Alexander Rose has a range of furniture covers. They come in a breathable material and feature a pull-cord at the base so the cover fit snugly. Avoid unbreathable plastic covers - poor ventilation will result in sweating and molding.
Every 2-3 years, a sealer can be applied to hardwood furniture. A sealer serves as a sunscreen and is applied mostly for cosmetic reasons, as it helps to preserve the original colour of the wood: Prolonged exposure to the sun induces the natural oils in the wood to rise to the surface and form a layer of patina that changes the colour of the wood to silver-grey. As mentioned earlier some people prefer this colour, but if you want to treat your furniture, only do it during warm and dry weather - treating wood when it is cold and damp will promote mildew spots.
Apart from Alexander Rose's own line of oils and sealers, Mid Ulster Garden Centre recommends Woodoc as an alternative. The advantage of Woodoc is its simplicity and low maintenance: Exposed to weathering, the sealer biodegrades and "disappears" from the wood. After one treatment, all that is needed is a thorough clean down with steel wool and mineral turpentine before any reapplication is needed in approximately 2 years, and no more scraping and heavy sanding will be needed to remove hard, chipped and flaking surfaces. Compared to other products in the market such as Danish Oil, which requires more frequent reapplication, Woodoc products provide a good balance between high quality, low maintenance and reasonable price. Moreover, Woodoc treatments are non-toxic when dry, so can be used on indoor furniture as well. Woodoc sealers come in 1-litre cans and last for about 3 years for a standard 5ft bench.
For additional colouring, Woodoc Stain Concentrates can be added to the sealer, adding an ebony, imbuia or rosewood taint to softwoods such as pine while refreshing the natural colour of darker woods:
For furniture that is quite far gone, Woodoc's Wood Reviver
is ideal for cleaning weathered and blackened wood, effectively removing blackening and greening of wood due to fungal and algae growth and greying from exposure to the sun.
Above information should give you some pointers to get started, but don't hesitate to give us a call on 028 796 42324 if you have questions - Jim, Peter and Mid Ulster Garden Centre's outdoor furniture team would be happy to provide more specific guidance!