Answers to some of contractors’ most frequently asked questions about spring deck care, answered by Rick Watson of Sherwin-Williams Product Information.
The exterior concrete deck I plan to stain is old and porous — my customer says it has never been previously coated. How should I handle this situation?
As always, you want to make sure the surface is completely clean and free of any grease or contaminants that could interfere with the adhesion.
To make sure there is not a sealer on the concrete, just sprinkle some water on it.
If the water soaks in, that is the indication there is not a sealer on the concrete. Once clean, dry and sound, stain away.
If it beads up, that indicates there is a sealer present and you’ll need to remove it. If not removed, your new stain, sealer or coating will likely not adhere.
If a deck is already stained, does the stain I put on it have to be the same kind — in other words, is a water-based stain compatible with an oil-based formula?
Normally there are a lot of reasons for re-staining a deck. It may be worn-out, discolored, peeling and flaking. Or, a customer might just want to freshen up what was on the deck previously.
Since some stains and sealers do not adhere well to others, it’s best to start by removing any old stain or sealer with a Deck Stain & Sealer Remover. This will remove stains and sealers that could prevent a new sealer or stain from adhering.
The next step would be to neutralize the stain remover. When the deck is dry, sprinkle some water on it. If the water soaks in, you are good to go.
If it beads up, that indicates there is still a sealer present and you’ll need to do the process over again until the stain or sealer is completely removed. If not completely removed, your new stain, sealer or coating will likely not adhere. If the wood is badly damaged, the best solution is to use a solid color stain.
Can I just use bleach to clean a deck?
We do not recommend bleach for cleaning decks, as it tends to be too harsh on the wood substrate and vegetation typically found around decks. We recommend the SuperDeck® line of cleaners.
The type of cleaning needed depends on which SuperDeck® cleaner we use. As always, read the application instructions carefully. Your Sherwin-Williams representative can guide you as well.
How long should I tell my customers to wait before they use their deck?
If conditions are mild — the weather is dry and the temperatures are in the 70s — you could probably walk on it in a half day to overnight. I would wait at least a day or two before moving patio furniture back on the deck and returning it to active use.