Q: Following this winter’s heavy rain, I am refreshing my redwood deck’s protection from the elements.
For the past 20 years, I have used Cabot’s Solid Color Acrylic Deck Stain, which has worn pretty well. This year, I noticed some peeling on the boards most exposed to the sun. In some areas, the paint peeled in strips, revealing the bare wood. In these areas, there are some crevices in the wood, going with the grain.
The wood seems to be free of dry rot, but I am worried about the crevices and the fact that the stain didn’t really stain as advertised but pulled right off in strips. Any recommendations before I continue?
A: Solid-color stain is really just another name for paint. Cabot developed its acrylic deck stain to provide a durable, walkable surface. It leaves an opaque finish, similar to painted siding. This differs from the two other types of deck finishes: semi-transparent stain and colorless water-repellent penetrating finishes.
Cabot’s Acrylic Deck Stain contains more than 40 percent solids and pigments dissolved in water. Penetration into new wood is limited because these solids and pigments tend to remain near the surface. Conversely, semi-transparent stains and clear penetrating sealers sink deeper into the wood and do not form a water-repellent film on the deck surface.
Twenty years of life, with occasional refinishing, is darn good. That the failure of the finish is restricted to the areas most exposed to the sun tells us that the peeling is the result of the water content of the wood.
During this year’s prolonged wet winter, your deck boards absorbed more water than usual, not necessarily because of voids in the finish, but more likely from the unusual amount of rain. Sun beating on the boards heated the moisture in the wood, effectively steaming the finish off.
Follow the same steps in refinishing your deck as you would for repainting a wood-sided house. We wouldn’t start until you’re sure that the rain is done and the dew is off the roses.
As always, preparation is the key to a good paint job. Scrape off the loose finish, and feather the edges of the remaining stain with sandpaper to provide a smooth finish. Give the rest of the deck a light sanding to provide "tooth" for solid adhesion of the new finish.
Let the deck dry for a few days to be sure any excess moisture in the decking evaporates. Sweep or vacuum the decking for a debris-free surface, then apply a coat of primer to the boards.
As for the crevices you mention, we’ve had good luck using the automotive filler Bondo to repair defects in wood. Bondo is a two-part filler, a base with a catalyst. It doesn’t shrink as it dries and sands perfectly. Mix a small amount of material according to the instructions on the can and fill the crevices. When the filler is dry, sand it smooth. Then spot-prime the patches.
Finally, apply the finish. We’d make it a two-coat job, so wait a day and apply a second finish coat. Let the finish cure for a day or two before breaking out the margaritas.