The usual way to apply a wood sealer is to use a brush. You should use a soft brush and spread it onto the surface, just as you would do with paint. It is recommended to use fast, brisk strokes because this stuff usually dries pretty quickly. Before you get started, it is important that you give your deck a good washing. Any dirt or debris that might be present will prevent the sealer from adhering to that spot. Thus, there will be a weak point in your deck’s protective armor. It’s also important to protect adjacent areas from any potential overspray.
In many cases, you will need to do some basic restoration before you can apply your wood sealer. If the deck is damaged in any way, a sealer will only trap the problem inside. First, go over the surface of the deck and drive any raised nails that you might see. As wood swells and contracts, it pushes the nails upward. That creates snags and will ruin the nice flat surface that you need. Use a hammer and punch so that you don’t have to strike the surface of the wood.
It will also be necessary to remove any remnants of the previous finish. These little bits of peeling paint will keep your sealer from doing its job, so all of it has to go. This can most easily be done using a pressure washer. If that doesn’t take care of the problem, your next step should be to apply a deck cleaning solution. If this is done, be sure to wet the grass and plants around your deck thoroughly. That way, any runoff will be diluted and made weaker. If you don’t do this, it’s very easy to kill your grass.