To give a wood deck the best protection and to keep it looking good, you should maintain it with a quality stain/sealer. Here are some stain application tips we’ve learned over the years.
Dry it First
For newly constructed decks, let the wood weather before staining. For decks built with treated lumber, the waterborne preservative leaves moisture in the wood. This is why fresh PT lumber often arrives wet from the supplier or is still damp at the lumber yard, and the moisture can impede the penetration of stains and paints. For best performance of stain coatings, allow treated wood to dry 2 to 4 weeks prior to application after the decking is installed. Drying time will depend on how much time has elapsed since chemical treatment, the wood’s exposure to the sun, ambient weather and temperature, etc.
For decks built with exotic hardwood, the wood needs time to weather. Exotic hardwoods are dense and can contain a large amount of natural oil that can block wood stain from penetrating. After construction, let the natural elements of sun, wind, and rain help you out by breaking down the surface of the wood, so the oils dry out and stain will be more easily absorbed.The more the wood weathers, the easier it will be to stain the hardwood.
Keep it Clean
All wood needs to be cleaned well before staining. It should be obvious that dirt or mud should be cleaned off before application, but brand new lumber should be cleaned to remove “mill scale” (a crushing of the wood grain during the milling process that can prevent stain penetration).
For the best-looking finish on an older deck, graying from the sun, mildew and old stains all need to be removed prior to staining. Oxygenated bleaches are highly effective at cleaning the wood, plus they won’t harm surrounding plant life and vegetation. Rinse off the bleach thoroughly.
Strip and Brighten?
For previously stained decks, stain strippers can help prep the surface. Formulated using sodium hydroxide, these chemical strippers can be effective at breaking down the surface of the wood, opening its pores to make it more absorbent. If using a stripper, it’s also a good idea to use a wood brightener. A wood brightener will neutralize the effects of the stripper and, similar to the stripper, the brightener will help to open the porosity of the wood even further for the best stain penetration. Again, rinse thoroughly and give the deck time to completely dry for a day before staining.
Try to avoid staining in direct sunlight. The heated wood and sun both tend to dry the stain/sealer nearly as quickly as you apply the product, which can lessen your working time, impede finish quality, and possibly reduce absorption into the wood. On the other hand, you should also avoid staining within 24 hours of rain, so staining on an overcast day can be risky. Keep an eye on the forecast and use your best judgment. Morning and evening hours often make better application times than high noon.
Type of Stain
Traditionally, oil-based deck stain/sealers have been considered the go-to choice for a long-lasting penetrating finish. However, water-based stains have made great strides in performance and can offer some real advantages--namely, they clean up with soap and water, and there are no harsh solvents to breathe. Research your product and check its warranty.
Semi-transparent stains will allow the natural wood grain and color variation to show through the finish. Solid stains will give an opaque finish to the wood, which conceals the woodgrain but retains its texture. The choice is yours, but make sure you understand the difference.
Read the Container
Everything that you need to know about your product is on the back of the can. Take a few minutes to read it before you begin. Not all products are meant to be applied the same way. What is the drying time? How many coats should you apply? How much time between coats? Is there a critical re-coat time?
Brushing is Critical
You have options for application: brushes, rollers, sprayers, stain pads, etc. Regardless of how you apply the stain, it is very important to brush the product into the wood grain. If you roll it on first, then back-brush it into the grain while it is still wet. The same applies for spraying. When you brush the stain, the brush creates a friction that breaks the surface tension of the wood and works the stain into the pores.This step achieves much better penetration of the stain.The more stain the wood absorbs, the longer the project will last before requiring maintenance coats.
Wipe off the Excess
If you apply more stain than the wood can absorb, then wipe off the excess. When you apply too much stain, it puddles on the surface and looks bad because of the uneven tone. Furthermore, those spots are likely to flake and peel over time. Apply only as much stain as the wood can easily absorb. - M. Weber