Sealing & Painting
Treated Wood
By David Bowyer
Preservatives make pressure-treated
wood resistant to insect attack and rot,
but the chromated-copper-arsenate
(CCA) treatment does not prevent
cupping, cracking, warping, or checking.
This kind of damage is caused by
water and sunlight, not biological
activity (see "What Ages Wood?", next
page). To shield the wood's surface
from water and sunlight, and keep it
looking good, you need to protect it
with sealers and stains or paints.
Sealers
Sealers are penetrating coatings,
generally clear or lightly tinted, that
repel moisture. Their effective service
life is only one to two years, with most
manufacturers recommending an
annual reapplication. Sealers make
good undercoats for stains or good preprimers
for paints. Many paint manufacturers
are now recommending sealing
before priming.