Evening star., 1940-01-20
Good PainfzoInI n Dry
Wood Advised for
Satisfaction
Priming Coot
All Important for
Lasting Surface

Lasting Surface
Paint failures are most frequent
" the result of faulty paint. or
heavy moisture content in the ma
terial before painting.
Cracking and scaling are two
more common enemies of q, good
paint Job. Cracks, as a rule, go
through to the wood. Moisture
penetrates these cracks, gets be-
hind the paint, and forces it away
from the wood causing scaling.
Cracking is caused by paint which
Is so hard and brittle that it can
not move with the wood as it ex-
pands and contracts from moisture
and temperature changes.
The type Of failure is particular
" troublesome because all the old
paint must be removed by the ex-
pensive process of burning and
scraping before repainting. The
trouble can be avoided by using
pure white lead paint or a high
grade mixed paint, which produce
q tough but elastic paint film.
Surplus Moisture Troublesome.
Blstering and peeling of paint
are due to the presence of surplus
moisture in the wood. Wet wood,
that is, wood containing water in
excess of its fiber saturation point,
Is in a condition susceptible to
blistering and peeling of the coat
ing. This will be true whether the
wood was wet when painted or be-
came wet after painting.
When painted surface, beneath
which the wood is wet, becomes
heated, part of the moisture is
vaporized and the resulting gas
pressure forms blisters. If examined
shortly after their first appearance,
typical moisture blisters are found
to be turgid water-f filled pockets be-
tween coating and wood. On pune
turing them, water flows out. The
coating then can be taken by the
loosened edge and peeled off, leav-
ing the bare wood exposed. Quite
often the water-saturated paint
film is tough and elastic and its
adherence to the wood so weak
that the tear does not stop at the
edge of the blister but continues so
that the coating can be peeled off
in sizable pieces.
If the blisters are not punctured
when full of water, and good dry
ing conditions prevail for some time,
the moisture will probably evapo-
rate or pass out, leaving the loos-
ened portions fairly intact, but they
will hang in a somewhat flabby
fashion.
Printing Coat Important.
The best method of preventing
paint failures is to use a good paint
on a dry surface. The priming coat
is the most important of all coats
for upon its adherence to the wood
all subsequent coats depend as does
the success of the paint job. There
fore, If the paint next to the wood
is bad, good paint on top is worth
less.
When applying paint to new
pitchy lumber it is advisable to use
a thin priming coat, adding to each
gallon of paint two or three pints
Of pure spirits of turpentine or
thinner, and mixing thoroughly. The
thinner will carry the paint into
the pores Of the wood thereby pro-
viding a good substantial bond"
Furthermore, the paint will dry rap
idly to a hard surface which provides
a permanent foundation for the fol-
lowing coats.
Hiding power must be sacrificed on
this coat in order to secure thorough
penetration and hard drying A thin
printing coat, well brushed in, per-
mits what is called valve action"
with the result that exterior mois-
ture is excluded from the pores of
the wood and the interior moisture
Is permitted to escape through the
thin film, as the action of the sun
brings to the surface the resin or
sap.
Putty In Nail Holes.
If paint is to be applied to new
clear lumber the priming coat
should be thinned by adding one
quart of raw linseed oil to each
gallon of paint and one pint to one
quart of pure spirits of turpentine,
or thinner. The priming coat should
be allowed to dry thoroughly for
at least a week. All nail holes and
other imperfections should then be
puttied with good putty made from
approximately equal quantities Of
whiting and raw linseed oil. The
second or body coat may then be
applied
For this coat, to each gallon of
paint add one pint of thinner and
mix thoroughly. Do not add linseed
oil or you will experience difficulty
from crawling" when the third or
finishing coat is applied. Allow this
coat to dry one week, if possible.
Be sure you do not apply the Sec
ond or third coats until the under
coat is thoroughly dry, otherwise
wrinkles" and "blisters" are apt
to result.
Apply the third coat of paint as
1t comes from the can being sure
1t is we'll mixed. If paint is too thick
in cool weather, small amount Of
linseed oil may be added to this
coat. Do not add thinner.
Gtroefrar foreS in Pnuoo have