White Oak lumber is a good choice for outdoor projects *** But *** it will
discolor from its original color as it weathers. White oak is a open pored
lumber and has a large amount of tannan in it. The grain of the wood will
start to turn black as soon as it is exposed to iron that is contained in
most water, including rainwater. The only way to prevent this is to
completely water proof the surface of the oak lumber. You will have to
recoat the lumber almost every year to keep moisture from getting beneath
your finish and discoloring the wood. Most varnishes, without constant
maintenance, will not tolerate constant, long exposure to the suns UV light
and still maintain a water proof surface. Spar varnish is a starting point
and a sutable finish if you are willling to recoat it from time to time(at
least yearly).

West Systems sells an epoxy system that is used a lot in boat building and
is designed to waterproof outdoor woods. I have had good luck with their
epoxy on white oak after several bad experiences with varnishes and
polyurethanes. Their epoxy uses a special hardner that turns the epoxy a
amber color that is similar to the color of wood that has had oil based
varnish applies to it when it is applied to white oak. The epoxy if left
uncoated will not stand up to the UV of the suns rays. So, you will have to
coat the epoxy with a UV blocking material after the white oak has been
water proofed with epoxy. White oak is one of the most difficult of the
woods to keep from showing black streaks in its grain structure because it
is so reactive over a period of time with trace amounts of iron that is
almost always in water. If any part of the finish on white oak developes a
hair line crack, a surface pore fails to be completely filled, or if the
finish is thin enough in a tiny spot to let water under it, then over a
short period of time that spot, crack, or pore that is subject of water
invasion will turn black/grey.


"Chaprock" wrote in message
...
I recently finished White Oak Adirondack chairs with Watco Teak Oil. Now,
a
week and a half later, the recipient says that black dots are appearing on
the wood. Sounds like mold to me. I switched to this finish because I
read
that this could happen using linseed oil outdoors. The Teak Oil
descriptions 'sounded' perfect for this type application. I applied the
oil
with the wood completely dry. Looks like I'll have to sand and start over
with something else.

Any suggestions here? Has anyone used Watco Teak Oil in this manner? Has
anyone had good luck with a particular exterior oil finish? Any help here
would be greatly appreciated!

Thanks.

CC