Winnipesaukee Forum - View Single Post

SummerIslander · 04-08-2022, 12:47 PM

From my experience, it's mostly about moisture control. Paint and other deck/dock outdoor finishes will peel off unless the wood is first sealed against moisture movement in-out of the wood on all sides. For years, when doing new construction for docks/decks, I seal all cut parts with cheap polyurethane cut ~25% with paint thinner so it can soak in and penetrate the wood surface, not just sit on top of it. After a week or so (yes, it adds time to the project) I will paint with an oil-based deck paint on top, or in the case of porch rails and such that are not traffic surfaces, exterior latex works fine also.

For post or leg ends in contact with the ground in in the lake, I mix up a bucket of the sealer and let the ends soak in 3-4" for a few hours so it really penetrates the end grain. Needs at least a week for the ends to dry since it soaks up so much.

In the first couple of years, the paint may not adhere in a few small spots, so touch-up annually. But I've found that the paint never peels off wholesale because the moisture in the wood is stable, internal moisture is not forcing up below the paint sitting on top of the wood, rotting the thin surface layer, and causing the paint to lose adhesion. The paint protects the poly sealer from sun/UV so the poly will not deteriorate as it would with a 100% clear poly finish.

For existing structures exposed to the weather, sealing all sides of the wood when dry may hard to do, too much power washing off dirt, waiting to dry that, then crawling under and still unable to get the sealer into any joints.

For pressure-treated wood, it is always important to let it dry out completely in a covered location for a couple of weeks or even months before putting any coating or sealer on it. It almost always comes wet from the lumberyard. If you seal in the moisture, coatings will peel forever.

In theory, a good oil-based deck paint should penetrate and seal the wood surface the same way, but most seem too thick to really penetrate as well as the thinned poly does, and you cannot thin a deck paint. I have not seen any water-based products lasts long on deck or dock surfaces.

04-08-2022, 12:47 PM	#26
SummerIslander Junior Member Join Date: Feb 2017 Posts: 14 Thanks: 0 Thanked 7 Times in 4 Posts	seal before paint on outdoor wood From my experience, it's mostly about moisture control. Paint and other deck/dock outdoor finishes will peel off unless the wood is first sealed against moisture movement in-out of the wood on all sides. For years, when doing new construction for docks/decks, I seal all cut parts with cheap polyurethane cut ~25% with paint thinner so it can soak in and penetrate the wood surface, not just sit on top of it. After a week or so (yes, it adds time to the project) I will paint with an oil-based deck paint on top, or in the case of porch rails and such that are not traffic surfaces, exterior latex works fine also. For post or leg ends in contact with the ground in in the lake, I mix up a bucket of the sealer and let the ends soak in 3-4" for a few hours so it really penetrates the end grain. Needs at least a week for the ends to dry since it soaks up so much. In the first couple of years, the paint may not adhere in a few small spots, so touch-up annually. But I've found that the paint never peels off wholesale because the moisture in the wood is stable, internal moisture is not forcing up below the paint sitting on top of the wood, rotting the thin surface layer, and causing the paint to lose adhesion. The paint protects the poly sealer from sun/UV so the poly will not deteriorate as it would with a 100% clear poly finish. For existing structures exposed to the weather, sealing all sides of the wood when dry may hard to do, too much power washing off dirt, waiting to dry that, then crawling under and still unable to get the sealer into any joints. For pressure-treated wood, it is always important to let it dry out completely in a covered location for a couple of weeks or even months before putting any coating or sealer on it. It almost always comes wet from the lumberyard. If you seal in the moisture, coatings will peel forever. In theory, a good oil-based deck paint should penetrate and seal the wood surface the same way, but most seem too thick to really penetrate as well as the thinned poly does, and you cannot thin a deck paint. I have not seen any water-based products lasts long on deck or dock surfaces.