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A friend of mine asked me what he should use to treat an outdoor swing that is made of pressure treated lumber. Would a deck sealer work? He didn't want to use anything that would leave a build up of finish on the exterior. Any input is appreciated.
 

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I have been told and tell all my customers that the treated lumber needs to weather a full year then you can treat it with anything you like.....the logic is that the treatment process is forcing a water based chemical into the wood and the added moisture needs to be allowed to escape before it is sealed or the escaping water will push the sealing material off its surface if finished to soon.
 

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I agree with Youngman, let it dry for a year. Then apply your Thompsons or any other quility sealer.
 

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Dido on the year wait

Deck sealer will work fine. You will most likly need to reseal it every summer though. Thomson deck sealer isn't the best on the market, just the most advertized. I recommend to my costumers to go a paint store and buy a good quality sealer. Paint stores carry way better products than your local lumberyard.

Presure treated wood starts out kiln dried to a low moisture content then submerged in a tank of chemicals and pressurized to 20 or 40 psi for an extended amout of time. Basicly the wood absorbe the chemical to the core. In the warmer climates you can seal the treated wood a little sooner than a year. But up north in the colder climates I would think it would take a year or more.
 

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Deck Cleaning and Sealing PT lumber

The whole "let it dry out for a year" thinking is a myth. Actually most of the damage is done during that time. After a year, even up here in northern Indiana, PT lumber will be cracked, split and greyed out.

Rain and even morning dew are absorbed into the wood almost every day and as it warms up the wood dries. This causes the wood to constantly swell and shrink, and it's these repeated actions that cause the splitting and cracking (water damage).

The greying is dead wood fibers caused by the sun's damaging UV rays. This usually happens anywhere from 3-9 months depending on the location of the wood. If the swing is in full sun all day long, it won't take long at all. If it's shaded it will take a little while longer but still will grey before a years time.

What determines when the wood IS ready is the moisture content in the wood. I clean/seal decks for a living so I check this with a moisture meter. In my area PT lumber is ready to be cleaned/sealed in about 2-3 months. You can find a reputable wood restoration company in your area to hire. Or if you want to do it yourself then buy a meter or possibly rent one. Mines about $150 new, but they do have cheaper ones I'm just not sure how accurate they read. Check the wood in several different places including some of the underneath spots that are shaded, you want a consistent reading of 10% or less and then you'll be safe to use most any quality sealer.

I ditto what someone said about buying sealer from the paint store, not from Home Cheapo. Use an oil based penetrating semi transparent deck stain.

This post is already long so I won't get too detailed about the steps of cleaning the wood first. Even though the wood will still be fairly new it will still need cleaned properly before sealing. I will just say that the number one reason a sealer fails is because the wood was not prepped properly, so do your homework on this.

So to summarize check the moisture level in about 2 or 3 months time, when it's 10% or less, it will need cleaned and neutralized properly, then allowed to dry for approximately two days or until the moisture content is 10% or less again, and then sealed. Hope this helps. :thumbsup:
 
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