Help!! Why is my white oak table "bleeding"? And other questions??

Tannins in the wood are likely responsible for the staining. Same thing if you let leaves stay on it too long and if they get wet. I’ve not yet done anything about the staining we get from leaves on our driveway, but it seems like they mostly go away over time in our case. Washing and scrubbing or power washing would probably do it at this point I would imagine

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Thompson Water Seal is waxed based, if you use it, it will give finishing problems in the future if you want to use something else.

White oak is an excellent outdoor wood due to its weather resistance and durability. The tannins in the oak, however, are water soluble and can/will leach out and probably what has stained the concrete. These are independent circumstances. The loss of tannins hasn’t affected the weather resistance of the wood, just the concrete.

I’m sure there are ways of removing the stain, but I don’t know them off the top of my head. I suspect pressure washing would take care of it, as it should dissolve the tannins that are now in the concrete and dissipate them, but don’t know for sure. Hopefully someone else can chime in there.

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Thanks guys. So with these tannins… will this continue to happen or will they stop leaching out? I can’t think of how to prevent this from happening every time it rains. I’m not sure I made the right choice of wood species! Yikes.

Let me suggest untinted exterior paint for the finish (more in a minute). A true marine spar varnish will also work, but will cost more and be a little more work. Avoid (read that again:AVOID) anything in the box store labeled “spar varnish”.....at least if you equate “spar” with “outdoors”. Now, to the paint: the deep color paint bases (the ones they use for tints) are usually numbered 1 through 4, generally the higher numbers are for the darker colors and without tint they dry clear, much like varnish (if it’s an oil based paint). Oil based paints are getting harder to find and many of the acrylic exterior paints (water borne) have the same properties, but they tend to dry very clear (no amber cast) even though they look milky in the can. But these paints (exterior, mind you) have the UV inhibitors and hold up very well outdoors. That said, any outdoor finish requires maintenance, but the paint and the true marine spar go a long time between recoating. (check here for more info on the pain) Lastly a word about the box store spar varnishes: most of them are urethane formulas, and urethane doesn’t do well in high UV. Flexner tested some of them for UV resistance and concluded that while the Min wax product is labeled that it has UV inhibitors, it did so poor in the tests he wondered if if really had any at all in it. I suspect if the post was finished that would stop some of the staining you see, presumably the finish would keep most of the water away from the wood preventing the dissolution of the tannins.

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