Special decking oils are available that will do the job of caring for and sealing your deck - restoring and maintaining its original colour, or changing it to a newer colour. For us, best treatment for decking is with decking oil.
Wood - like all living things - is made up of a honeycomb of minute (microscopic) cells. Whether softwood or hardwood, the cells are there - empty, waiting to be filled up with whatever is available! Deck boards are different in one main respect to other timber structures outside.
Deck boards lay horizontal - not vertical like walled structures - so dirt and dust is not readily washed off. It simply lays on the deck until it finds a home. If it is larger than the cellular structure of the wood, then it will eventually wash off. If it is dust-like and smaller than the cell structure, then it will fill the available cell!
This cell structure can be 'capped' by using Decking Oil. Decking oil or stain? Decking stain, simply stains - very attractive too, but decking oil can stain and also preserve at the same time.
The fact that your deck has been pressure treated in the manufacturing stage, does not mean that it requires no further treatment to alleviate stains and grey-coloured decks.
Ordinary deck stain, simply colours the surface area of the timber. It does not fill up the cells, so dirt is still able to fill the spaces! A Deck Sealer is required to do the job - usually by way of a decking oil. There is a case to be made for just using stains in certain circumstances. Decking oil or stain needs to be thought out carefully. Preservation for the future is far more important than a cosmetic job!
Close up of a grooved softwood deckboard clearly showing the groove and also the grain direction.
Decking oil is a special treatment/preserver that - whilst applied as a liquid - has a high potential 'solids' content, so that when it dries it solidifies thereby filling the pores/cells. Deck oil has high penetrating properties, so that it can enter and then solidify in the individual cells. We would always say that the best treatment for decking is proper decking oil. Some deck stains simply coat the cells, still leaving room for the dirt to accumulate.
Penetrating oil finishes are much better for deck maintenance than polyurethane or varnish type finishes. Oils do not crack as the timber expands and contracts with the varying weather patterns. Deck oil treatments actually improve the structure of the timber, for once dry, the solids are stronger than the individual wood fibres that they bind together. Decking oils actually replace the natural oils and resins that get lost over time with deck timbers.
Decking oil should be applied after the deck has been thoroughly cleaned. We do not advocate the use of pressure sprayers, for if used indiscriminately a pressure jet can ruin the surface structure of the timber - leaving it with a 'wooly' feel - difficult to clean.
The oil should be applied in two coats using a soft-haired paint brush. The soft-haired option will allow for even spreading of the deck oil and also act as a sponge to mop up any surplus deck oil, which can then be used further along the board.
A 5 litre
The oil should be applied thinly and well brushed out to ensure no puddles of surplus oil is left on the deck. This is particularly the case with grooved deck boards, as surplus oil can linger in the grooves, giving an unsightly appearance, and also taking a long time to dry.
With a thin application, the first coat will normally be touch dry in an hour in ideal weather conditions. A second coat is necessary to further protect the timber and also to enhance the colour if using a tinted oil.
The picture clearly shows the difference a second coat will make. The lighter section has received just one application of deck oil. 4 hours later, the second coat of oil was applied. As well as being the best treatment for decking, oil actually seals the pores as well as being a good cosmetic finish.
The colour used here is Natural Cedar. If you decide to opt for a coloured oil - and it really does add impact to your deck - then always choose a lighter colour if you are uncertain. It is easy to 'darken' a lighter colour by oiling with the darker colour subsequently. It is virtually impossible to 'lighten' the colour after using a darker coloured oil.
We have never experienced any problems when treating boards that are slightly damp. The spirit carrier within the decking oil still ensures good coverage and penetration of the oil.
A 5 litre can of oil normally covers around 50 sq metres of deck with 2 coats.
Here it is possible to see that the deck board to the left has been over-applied with deck oil. This will result in filling of the grooves, and also a build-up of thick oil on top of the board, which will result in a long drying period, and a stick feel to the deck.
In the images below, 2 methods of application are shown. We prefer to apply the deck oil along the whole length of a couple of boards for a more even application. The left hand image method of application can result in 'over-painting' of some areas, leading to a patchy finish. The whole board length method also ensures good long brush strokes to spread the deck oil evenly.