Once your deck or pergola has been exposed to the weather for a while, you will notice that the colour starts to fade, the grain becomes washed out and the timber won’t look as good as it once did. When that happens, it’s time to re-stain. With most stains this will be required either once a year, or once every two years. To ensure the stain goes on evenly, it's important that you first give your deck or pergola a good clean.
How to clean the wood
To get a deck or pergola clean, you don’t need to spend lots of money on special wood cleaning detergents; the active ingredient in most of these cleaners is sodium percarbonate and it's used in plenty of other household substances, including Napisan and its generic alternatives.
Add about 2 cups of Napisan or a generic alternative to half a bucket of hot water and you have a great solution for cleaning the wood with. If you don't already have one, buy a stiff bristled decking brush from a hardware store and give your pergola or decking timbers a light scrub while applying the cleaner. Leave the solution on the wood for about 15 minutes or so, add a little more to wet the timber again and then give it a really good brush down. Rinse it off thoroughly and allow it to dry. For pergolas, you may not be able to let the solution sit on the wood for quite as long so you may need to re-scrub several times to achieve the same results.
If there is a build-up of stain in the wood, you may need to take more drastic measures and use a commercial stain stripper. This won’t get rid of any stain that has soaked deep into the wood, but it will certainly get rid of any surface staining. Be careful using stain stripper as it is caustic and can harm you as well as any plants or pets that come into contact with it. Any small spots of stain that won’t come off with the stripper can be sanded out gently.
Using a wood brightener
Before applying the stain, you may wish to spray on some wood brightener. This product neutralises any residual stain stripper and opens up the wood to improve penetration of the next coating of stain. This can be especially useful on wood with a long accumulation of stain in the grain. In most cases you simply spray this on, leave it sit for a few minutes and then rinse it off.
How to apply stain to your timber
To stain wood, there is no better applicator than a paintbrush. A paintbrush’s bristles open up the pores of the timber and cause it to absorb the stain better. You may not use it for the whole deck or pergola, but it should at least be on standby for any touch ups. Applying too little is better than applying too much; if too much is applied and allowed to dry then the surface can become brittle and start to crack and peel, resulting in a horrible looking finish and a mess of stain flakes drifting around.
When applying stain to a deck, the idea is to run as far long a single board as you can without touching any of the other boards. Only when you’ve finished one row should you start to move on across the deck. Applicators should be able to cover four boards at a time, so you can do this but you will need to concentrate on coating each board evenly. Long, continuous strokes with sufficient oil to soak into the wood will net the best results. If this is your first time, try and test it on an offcut to see how much oil to apply to soak into the wood and how long it needs to dry for.
The directions on the tin should give you an indication of drying time and when to apply the second coat. Use less oil in the second coat than the first as the wood will not absorb as much of it and it may pool on the surface and become sticky. Use a rag with turps to clean up any marks or spills; the turps thins out the oil.
Stains applied to wood used in pergolas will be subject to running and drips, so be aware of this and clean up any little trickles and dribbles as you go.