Actually the process of varnishing or painting the woodwork and
metalwork on the house is the spreading of a thin protective coat, one
thousandth part of an inch thick or less, over the surface, in order
to protect it from the wear and tear of use and weather and decay.
And a marvel it is that any material could be found which spread in
so thin a film could withstand the chemical action of the sun’s rays,
the expansion and contraction of the surface over which it is laid,
the abrasive action of blown sand, hail, and rain, the natural wear of
walking feet and rubbing clothes and bumping furniture, and a dozen
other accidents which conspire to mar the surface of woodwork in the
home.
Is it a wonder that for this protective coat of varnish all experts
demand that the best materials be used? But out of ignorance it is not
always so, for the lower cost of varnish and paint is more evident than
the quality of the substance of which they are made.
The varnishes which are most used in good houses are made of
resins, melted in a kettle and mixed with linseed-oil, and thinned
with turpentine as they cool. They have the peculiar property, when
spread with a brush over a surface, of hardening by a chemical change
brought about by absorbing oxygen from the air, and making a strong,
transparent, protective coat over the substance upon which they have
been applied. The kind of resins[A] have much to do with the quality of
the varnish, since the linseed-oil and turpentine are apt to be about
the same grade in all varnishes. Dark or light varnishes can be made;
hard or soft and elastic surfaces can be produced; varnishes capable
of resisting the wettest kind of weather and those which turn white
under the least dampness are manufactured for various purposes, and
practically in all cases those varnishes which are the best are the
highest in cost.
[A] Varnish resins or gums are imported from countries that the average
man knows little about. The island of Zanzibar furnishes one of the
costliest and finest of gums. It is called Zanzibar copal and is the
gum of a fossil tree. New Zealand furnishes the most widely used gum,
kauri. It is dug out of the ground by the natives. The west coast of
Africa furnishes the gum known as Sierra Leone copal, which is used
much in automobile work.
The cheap varnishes which are the most abundant upon the market, and
which are used for cheap furniture and houses, are made of rosin
and not resin, or are resin varnishes adulterated with rosin. Most
houses erected by speculative builders are finished with cheap rosin
varnishes, but no architect should be guilty of specifying them, for
he should know better than to attempt to save money by purchasing the
poorer grades of varnishes, since the real cost of varnished work is in
the labor rather than in the cost of the materials used. These cheap
rosin varnishes cannot stand up under the sponge test, which is merely
the application of a wet sponge to the surface overnight. The next
morning the rosin varnish will be found to be white and dissolved down
to the wood, and will never recover its appearance. Better grades of
varnish may turn white under this sponge test, but upon drying return
to their original color, but the finest grades of varnish will not be
affected at all. The difference between these varnishes can also be
observed by rubbing the thumb over the surface of such a fine varnish
as is on a piano and noticing that no effect other than a higher polish
is produced, while if the same rubbing is done on a cheap varnish, it
will be crumbled off from the wood. Every one has seen the ugly surface
cracks which develop with age in old doors or upon old church pews in
musty churches of the dark ages of American architecture. In nearly all
cases these cracks are due to cheap rosin varnishes.
Before varnishing or painting any interior woodwork, it is important to
observe all the preliminary precautions, or else failure may result,
even though the work is conscientiously performed in the latter stages.
One of these early precautions is to paint the back of all trim for
doors and windows with some good linseed-oil paint, and apply a first
coat of filler to the outside surface, and all this as soon as it
arrives on the job. This is to prevent the wood from absorbing the
dampness which is prevalent in all new buildings, and as most trim has
been kiln-dried beyond ordinary requirements for construction work,
it is very thirsty for water, and will soak it up quickly from the
atmosphere. This trim should not be permitted to stand in the building
overnight without the priming coat. As the first coat of filler is
linseed-oil, there is not much excuse for not doing this, for it can be
applied very rapidly. Of course where the wood is to be stained with
an oil stain, the application of the linseed-oil before the stain is
applied will prevent the proper penetration of the stain into the wood,
and, as the architect generally insists upon seeing samples of the
staining work before it is applied, the above precautions of protecting
the wood as soon as it comes are often thrown to the winds.
And in connection with this matter of stains, a word may not be amiss.
Most manufacturers make among their many stains certain brilliant-red
mahogany colors, bright Irish-green colors, and horrible yellows. These
are made to meet certain gaudy tastes shown by the public, but of their
use by architects no word could condemn them enough. And on a par with
these stains is the varnishing with no stain at all of yellow pine
trim, an architectural atrocity which is committed on every hand in
small houses. The quiet browns, grays, grayish greens, and the like are
the only safe ranges of color for staining interior trim, for, after
all, the casing of doors and windows must blend in with the walls and
serve as a background for the furniture and not screech at it. And
directly in line with this statement should be emphasized the rule that
highly polished surfaces in varnishes for trim are as much out of place
as brilliant colors. Many architects prefer wax in place of the polish
of varnish, and with good reason. The manufacturers of varnishes make
certain grades which dry with a dull finish, and also show samples of
beautiful dull finishes which can be secured by the laborious method of
rubbing the final coat of varnish with powdered pumice-stone, water,
and felt.
But before any varnishing can be done, and for that matter any
painting, it is essential that the pores of the wood are filled, so
that the surface to be varnished has no soft and absorbent places, but
presents a hard and glossy body. Woods like oak, ash, and chestnut
have such large pores that paste fillers are required to fill them in.
These paste fillers consist of a solid part like pulverized quartz and
a liquid part of a quick-drying varnish. It is rubbed over the surface
of the wood and into the pores and permitted to set, when the excess
is then wiped off with excelsior and, finally, felt. When the wood is
stained with an oil stain, this filler may be colored to match.
Architects are often shown samples of the beautiful finishes which
are possible with the use of this or that manufacturer’s stains and
varnishes, and supplied with specifications by which they are told they
can secure these finishes, but much to their sorrow the results are not
like the samples, and probably never will be. All of these samples are
made under ideal conditions by the most careful experts. Laboratory
conditions and regularity and first-class skill can produce finishes
on a small sample board which could not possibly be reproduced in a
building except at enormous costs. In the first place, there is always
more or less dust blowing around in a newly constructed building, and
not the greatest care is taken in it to provide the exact control of
humidity and temperature required for drying varnishes. And, as every
one knows, the men who do the painting are generally far from being the
most skilful artisans of their trade. It, too, is a big temptation to
put on one or two heavy coats of varnish instead of three or four thin
coats, and there is not an expert living who can tell how many coats
of varnish are on a piece of wood after the work is done. Unless the
architect has observed each step of the application, he cannot deny,
when the painter shows him the finished woodwork, that there are not as
many coats of varnish on it as he required in his specifications. Yet
time will tell the tale, but then it is too late.
However, the treatment of floors and stair treads is the worry of
many an architect, although he ought to remember that in factories
sheet steel is laid on the floors at the doorways, and even this wears
through. Why should he be disheartened if after a year the stair treads
and the patches of floors near the door-sills are scratched down to the
wood through coats of varnish one-thousandth of an inch thick? Even the
best varnish will break down under this abrasion, but only the best
should be used. Cheap floor varnishes are not worth the labor of
laying, and yet how many spend money on them. Some architects, and with
good reasons, prefer finishing the floors with wax instead of varnish.
As a base for this wax, a thin coat of varnish is excellent. Various
manufacturers have different formulas for floor waxes, and they are
more or less complex, but generally turpentine is the softening and
drying material. The wax paste is rubbed into the floor and polished
with weighted brushes—a tedious job. However, it is a job which any
servant or housewife of ordinary intelligence can perform, so that
whenever the floors become worn around the doors or the stair treads
become shabby, the housekeeper is able to repair them easily, and there
is no doubt that a waxed floor is more beautiful than a varnished one.
But remember the slipping and sliding rugs on a wax floor and be sure
to fasten them down.
When examined critically, paint is not much more than a varnish with a
finely ground opaque powder, called the pigment, suspended in it. This
pigment takes away the transparent qualities of the varnish and gives
a definite color to the surface. Enamels actually do use varnishes as
their vehicle or base, but ordinary paint uses linseed-oil, which acts
much like a varnish, in that it has the property of becoming hard and
elastic under the oxidizing effect of the air.
The exteriors of most houses are painted with white-lead or zinc-white
pigments mixed with linseed-oil. Zinc makes a harder paint than
white-lead, but it is best to mix the two pigments together in the
proportion of one-third of zinc to two-thirds of white-lead.
In extensive investigations the U. S. Bureau of Standards suggests
that much saving of money in paint would be made if white paint were
abandoned altogether in favor of dark-colored pigments for exterior
use. Horrible suggestions, but these are the facts in the case! White
and light-tint paints invariably fail on the south side of a house,
before the paint on the other side shows signs of deterioration.
This is because the light of the sun breaks down the strength of the
linseed-oil, which is the body of the paint film. For this reason dark
pigments, which are more opaque, cut off the light and protect the oil
film more than the lighter-colored pigments.
Another common cause of failure in exterior painting is the application
of it to the wood during unseasonable weather, when the surface of the
wood is wet. Paint will only properly adhere to a wood surface when it
is free of any moisture.
Another one of the causes of failure of lead and zinc paints for
exterior work suggested by some authorities is the use of volatile
thinners like turpentine and benzine. They say that such thinners
should not be permitted on the job, for they are a temptation to the
painter. If raw linseed-oil is used, and it is necessary to shorten the
time required for drying, some good drier should be added, say 5 per
cent. This drier should be pale in color and free from rosin. Driers
are usually made of oil combined with a good proportion of lead and a
little of manganese.
White pine, Douglas fir, yellow pine, cypress, or any of these woods,
usually contain some knots, which are sure to damage exterior white
paint unless properly treated. These knots have a certain amount of
pitch in them, which will penetrate through any oil paint and leave an
ugly mark. They should be covered with shellac, which is not affected
by the pitch. Shellac is a spirit varnish made from shellac resins
dissolved in alcohol. The yellow shellac is the strongest, but the
white is used where a light-colored paint is to be applied on top of
it. The pitch which is so bad in knots is often distributed throughout
the wood, as in Southern yellow pine, and this will often cause
the paint to peel off. To prevent this to a certain extent, some
specifications advise using benzol in the priming coat, in order to
make the paint penetrate more deeply into the wood and get a better
grip on the surface.
The priming coat of any painting job should either be pure linseed-oil
or linseed-oil with very little pigment in it. Its purpose is to fill
the pores of the wood before the other coats are applied, for if an
ordinary thick coat of paint were applied to raw wood, the surface
would draw so much oil out of the film of paint that most of the
pigment would be left dry and unfastened upon the outside.
Only after the wood has been given the priming coat is it then time to
putty up the nail holes and other defects, and not before, because the
dry wood, as in the case of paint, will suck out the oil from the putty
and leave it without anything to bind it together. The best putty for
this work is made of linseed-oil with enough white-lead in it to make
a thick paste. The putty which is commonly used, however, is made of
whiting or ground chalk mixed with linseed-oil. This is durable if real
linseed-oil is used, but often some inferior adulterant is substituted.
After the holes are all puttied, the other coats of paint may be
added. At least two good coats should be applied, and three coats give
superior results. Plenty of time should be allowed between coats to
permit thorough drying of the previous one.