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HOW TO USE PAINT
BY ELIZABETH G. STOKELY
T H E three chief problems in
paint that confront the average
private householder today
have relation to laying the
preservative on wood, concrete,
or iron. Right consideration of
each individual problem means long-lasting
results, the preservation of the good
looks of, and above all. the longevity of
the object painted.
The bogies that pursue the painter—
even occasionally the professional, and
too frequently the amateur—are cracking,
scaling, peeling, "checking" and
"alligatoring".
Pretty nearly everyone has an idea of
what the first three terms signify.
"Checking" and "alligatoring" are
usually regarded as whimsical variations
of the cracking problem. There are,
however, distinct and preventable causes
for the latter phenomena. "Checking"
has reference to the development of fine
interlacing lines on the surface of the
paint. "Checking" on an extensive scale
is known as "alligatoring".
One paint authority says with reference
to these phenomena: "The outer
coats of varnish anil paint always tend
to shrink greatly in volume and to become
progressively harder and more
coherent, thus producing either of two
possible effects—one, the rupturing of
this outer coat with consequent alligatoring
or checking; the other is. the outer
coat becomes thinner without rupturing
—wdiich effect occurs depends on the
under coat. If it is soft, the outer coat
in oxidizing and shrinking will draw up
and slip over it with consequent rupturing.
If the under coat is sufficiently
hard, the outer coat does not slip over it,
and simply becomes thinner by shrinkage,
and no rupturing occurs. Alligatoring
also occurs whenever a paint is applied
over another paint that inherently
will not dry hard, as in the case of a
harder paint applied over a yellow ochre,
or an asphaltum paint."
The remedy suggested for these twc
evils is to have the under coat of paint
as hard as practicable. On the other
hand, checking is sometimes the lesser of
two evils. When the film of paint has so
great tensile strength that its surface
remains completely unbroken, the expansion
and contraction of the material
wdiich the paint covers may result in
cracking and loosening the paint, the result
being "scaling".
Every paint requires a drying oil. If
this drying oil is to have satisfactory
results it should possess the property of
being oxidized readily into a solid substance.
Since linseed oil is the most
satisfactory oil for the purpose, substitutes
should by all means be avoided.
Checking and alligatoring are surface
manifestations. Cracking goes deeper—
to the foundation, in fact. Scaling will
usually, as a matter of course, follow
cracking.
Cracking is caused as a rule by moisture
in the fiber of the wood base. As
this moisture dries out, the fibers contract,
forcing the paint surface to contract
with it. Consequently the paint
contracting with and across the grain,
is torn asunder. That is, cracked. The
mischief by no means ends here.
These cracks permit more moisture to
enter the wood. This moisture travels
under the film of paint, and literally lifts
or forces the paint up from its foundation.
Hence scaling follows. Moisture
under an unbroken paint surface in like
manner results in peeling.
A thick layer of paint inclines more
readily to crack and scale. Old layers
of paint therefore should always be removed
before new coatings are applied.
Sandpapering, of course, will remove the
old paint.
It is also an excellent idea to have the
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