Q. Dear Umbra,

With all the news about the declining health of our waterways (Puget Sound is my local water body), I’m nervous about resealing my deck this summer. The self-proclaimed eco-friendly options are $55/gallon and up. Are there options to protect my deck and Puget Sound that won’t break the bank? Thank you thank you!

Gordon P.
Somewhere near Puget Sound, Wash.

A. Dearest Gordon,

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Because you declined to specify exactly where in the Puget Sound region you are, I’m picturing you researching deck finishes from a top-secret bunker. I love that your bunker has a deck, by the way. It must be lovely to escape the pressures of national security or international jewel smuggling or whatever else it is you do down there with a nice coffee break in the sun. Let’s get that deck of yours sealed so you can take your breaks in style.

It might cheer you to know that the actual act of sealing or staining your deck (which I’m assuming is wood, as finishing isn’t as big a deal for plastic composite lumber) doesn’t pose much risk to local waterways. But here’s the buzzkill: Cleaning your deck, a key step before sealing it, can affect waterways and must be done carefully. Not only that, but sealers also have other, non-watery impacts to consider — we’ll get to that in a moment.

Since it’s the health of Puget Sound that has you worried, we’ll start there. Decksperts recommend cleaning the planks after removing existing wood treatment to ensure an even surface that’s ready to receive your new seal. But chemical cleaners, including those containing chlorine bleach, can wash into the water supply when you rinse them off, and/or harm your garden or lawn. Your solution: use oxygen bleach, a safer alternative that’s reportedly terrific for this purpose. And then take care to channel the runoff onto permeable surfaces like grass or gravel, not into the storm drain. These areas act as natural filters.

Breathing easier about the Sound, Gordon? I hope so, as now we’re moving on to a different threat from deck sealing: air pollution from the volatile organic compounds (VOCs) found in many products made for this task. VOCs are bad news for the atmosphere because they contribute to ozone and smog formation, and they’re bad news for you and your bunkermates because they’re linked to headaches, dizziness, respiratory problems, and even cancer. It’s best not to use ’em at all, or to seek out low-VOC products instead.

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In the world of deck maintenance, that means water-based sealers and stains. The solvents used in oil-based products emit far more VOCsand they require the use of toxic paint thinners to clean up. Water-based formulas, on the other hand, come in low- and zero-VOC versions, can be cleaned with soap and water, and also dry faster than their oily cousins. And while oil-based paints have a reputation for penetrating more deeply into wood, the latest water-based brands are doing a better and better job in that department.

And now for the pocketbook issue. As a sad-but-true general rule, eco-friendlier, less-toxic products sometimes carry a premium price. There’s always the chance you can shop around or turn up something suitable on sale: I’ve rustled up a few options in the $40/gallon range at big-box stores, and it never hurts to get to know your local green home store. But sealing the greener way just might require a bit more cash. Only you can decide whether the extra cost is something you can swing — and whether it’s worth paying a little more for the peace of mind that comes with knowing you are making a choice that’s better for the planet and for your health.

One thing you can do to spread out your investment is choose the longest-lasting sealer you can find. It’s tough to make general recommendations for you, Gordon, as the best product will depend on what kind of wood your deck is made of and what kind of look you’re after — do you want the natural color of the lumber to shine through, for example, or is it okay to cover it up with a more opaque tint? If you’re open to the latter, that could be happy news for your wallet: solid pigments tend to last the longest (three years or more), in part because they’re the best at fending off UV rays; clear stains that preserve the wood’s grainy look often need replacing every year. Solids also have the bonus of covering up any unsightly flaws if your deck is particularly old or weathered, but bear in mind that they need to be applied carefully — too many coats, and they run the risk of flaking or chipping. Semi-transparent sealers fall somewhere in between and could be a good option if you can’t find a solid pigment that works.

Happy shopping, and best of luck on this and any other bunker-improvement projects you undertake this year. Recycled kitchen tile can really add a pop of color to even the darkest underground lair.