- Q.On elevated decks, the
redwood decking often causes black streaks on the
joists below. How can we prevent this?
A.Redwood contains
tannins and extractives that are water-soluble. The
extractives will wash down onto the wood below,
leaving brown or black streaks. The best way to
minimize this streaking is to treat the redwood
with a water repellent. If the water does not
penetrate the redwood, only a minimum amount of
extractives will dissolve to wash down on the wood
below.
According to work done by Brian Buchanan of the
Texas Forest Service, the best water repellents are
clear or cedartone Amteco Roof and Deck Sealant
(Amteco Inc., 815 Cass Ave., St. Louis, MO 63106;
800/969-4811), ABR Natural Seal X-100, (American
Building Restoration Chemicals, 9720 So. 60th St.,
Franklin, WI 53132; 800/346-7532), Seal-Treat II
(W. M. Barr Co., P.O. Box 1879, Memphis, TN 38101;
800/238-2672), and WoodGuard (Chapman Chemical Co.,
6075 Poplar Ave., Suite 306, Memphis, TN 38119;
800/238-2523). For color maintenance, Amteco TWP
tested best.