This branch of woodwork is a trade by itself and under modern methods
of specialization the men who do this work do nothing else. The methods
of finishing are legion and every polisher has a few little "kinks" of
his own which he regards as trade secrets.
The personal equation enters very largely into the work, and if twenty
boys have a given method explained to them and they all polish, say, a
box of the same size and material, there will result twenty different
kinds of polished surfaces.
This is due to difference in temperament. Some boys are patient and
painstaking. Others are nervously anxious to get through and see how it
looks. It is a fact particularly true of finishing that it cannot be
hurried without endangering the result. Every coat must be thoroughly
dry and hard before the next one is put on. Different woods require
different treatment, and the elements of good taste, colour, and
harmony all enter into the problem.
These statements are not made to discourage the young woodworker,
because finishing can be done well by any boy who will use reasonable
care, but to emphasize the fact that it is poor policy to make a fine
piece of woodwork and then spoil it at the last moment by hurry.
Staining is something on which opinions differ greatly. Some artists
claim that only the natural colour of the wood should be used, but a
great deal of staining is done, and we must leave artistic arguments to
others.
The extent to which staining is carried may be illustrated by the
following finishes used on one kind of wood--oak:
Golden oak Antwerp oak Rotterdam
English oak Ox blood Antique
Forest green Weathered oak Cathedral oak
Austrian Flemish brown Flemish green
Silver gray Sumatra brown Filipino
Mission oak Malachite Fumed oak
Bog oak
The writer believes that staining to make imitations is wrong, such as
staining cherry or birch to give the impression of mahogany.
The list of materials for staining is very bewildering, and it is
advisable to reduce the list to a few reliable ones and learn to use
them well. They may be divided roughly into three classes: oil stains,
water stains, and stains produced from drugs or chemicals.
Oil stains are dry colours ground in oil such as chrome yellow,
Prussian blue, burnt umber, burnt sienna, etc. When preparing one of
these for use, thin with turpentine and linseed oil and apply with a
brush. After it has stood for a few moments rub off with a piece of
cotton waste or rag.
Water stains are colours dissolved in water.
After applying this kind allow it to dry. Sand-paper the surface flat
and apply a second coat of half the strength.
Stains produced from drugs and chemicals include such materials as
logwood, bichromate of potash, ammonia, iron sulphate, acetate of iron,
etc.
The preparation of the surfaces to be finished is very important and
means the removing of any defects, such as scratches, by means of
plane, scraper, and fine sand-paper.
These defects always show much more prominently after polishing than
before, so that too great pains cannot be taken in preparation.
Assuming that the surface is ready, the first question to be considered
is whether the wood is open or close grained. If an open grained wood,
a coat of filler may be used; if close grained this may be dispensed
with. The following list will enable the beginner to decide:
Open grained woods requiring filler: Oak, ash, chestnut, mahogany,
walnut, butternut. Close grained woods; no filler required: White
wood, pine, cherry, birch, beech, gum, sycamore or buttonball;
maple, cedar, cypress, red wood.
Filler may be made at home, but it is a staple article to be found
in paint stores and it is advisable to buy it ready made. It comes
in paste and liquid forms, and the paste is recommended. It must be
thinned with turpentine to the consistency of cream and applied with a
brush. As soon as it begins to dry, rub off the excess across the grain
with a handful of excelsior, waste, burlap, or rags and allow it to
stand over night to dry.
When the wood is to be stained the colour is frequently mixed with the
filler.
The object of all this is to fill up the pores of the wood to give a
flat, solid surface for the polishing. Sometimes even on open grained
woods filler is omitted entirely.
Suppose that the work in hand is a footstool or tabourette made of oak
and we wish to give it a forest green finish.
The process would be as follows:
[Illustration: Photograph by Helen W. Cooke. Staining and Polishing]
Prepare the stain by mixing a small quantity of chrome yellow and
Prussian blue on a piece of wood. Mix thoroughly with a putty knife
or old chisel and thin with boiled linseed oil and turpentine; add
blue or yellow until a beautiful dark green is obtained. Add this to
the filler, using turpentine for thinning, until the whole mass of
liquid is the desired colour and as thick as cream. Paint the footstool
all over with this filler. As soon as it starts to dry, rub off as
explained.
The next day sand-paper smooth and give a coat of shellac. When hard,
sand-paper flat and give a second coat of shellac.
From this point on the process depends on whether a glossy polish is
desired or a dead flat surface. For an article of furniture like a
footstool a highly polished surface would be a mistake, as it would
soon be scratched, and while furniture is not to be abused, it is to be
used, and shoe nails make scratches.
A dead flat surface may be obtained by rubbing down the third coat of
shellac with fine ground pumice stone or rotten stone and water. If too
flat, rub the surface with raw linseed oil and wipe dry.
Some boys will obtain a better finish with two coats of shellac than
others will with four.
After the first coat of shellac, varnish is often used for the
remaining coats, but it takes much longer to harden and requires
careful handling.
Shellac is a product obtained from certain trees in the Orient. It
may be bought in the dry state at paint stores and dissolved in
alcohol. Grain alcohol is the best and most expensive, but wood
alcohol is cheaper and will answer all ordinary purposes. The shellac
may be bought in cans all ready for use, and there are two distinct
kinds--orange and white.
White shellac is the more expensive, but should be used on
light-coloured woods, such as maple, to avoid spoiling the colour.
Varnish comes in so many grades and kinds that it is best to go to a
reliable dealer and tell him just for what purpose you expect to use
it. There are outside varnishes, rubbing varnishes, light flowing
varnishes, etc.
When by exposure it becomes thick so that the brush drags, it should be
thinned with a little turpentine.
There is a great difference in the methods of using shellac and
varnish. The former being dissolved in alcohol evaporates quickly, so
that it must be put on thinly and as rapidly as possible. Varnish,
on the other hand, may take forty-eight hours or more to dry, so that
the brush can be drawn over the surface several times to remove air
bubbles. It is not possible to do this with shellac. The brush used in
shellac should never be laid on the top of the jar or can, as it will
harden in a very short time. The care of brushes is an important item.
Varnish brushes should be cleaned with turpentine, shellac brushes with
alcohol, and when cleaned it is better to keep all brushes in a pail of
water than to allow them to become dry.
The jar or wide mouthed bottle used for shellac should be kept covered
else a great deal will be lost by evaporation. A jam jar makes a
convenient receptacle for this, as it has an opening wide enough
to allow the use of a flat brush. Evaporation may be prevented by
inverting another jar of the same size over it. The shellac on the rim
will hold them together practically airtight with the brush inside.