Omaha daily bee., 1911-02-26
What is Done to
Finish the Wood
Cases of Pianos
Valuable Information Concerning the
Peouliarities of Highly Polished
Surfaces on These instruments.


panel seems to show hills and deep valleys
in curving fluctuations. What the owner
sees and wants Is superb wood with It's
wonderful tracery and net work OF nberB
brought out to the greatest advantage
This article VIII Try TO show how the
polish is secured and why It is fragile.
Narnish is a combination Of copal gum
and drying oil. with turpentine a. a thinner.
Copal gum Is a fossil resin. 1t Is like am
Der, only centuries younger. II Is brittle
Ike amber. Copal gum gives hardness to
varnish. and in general. the harder the
varnish. the better it will polish; but brittle
ness goes with hardness. and cracking
sometimes goes with brittleness.
Oil gives elastioy and cohesiveness: the
more oil the less liability to crack. but the
polish may die away. sinking" in is the
trade term.
In general pianos are finished In the
following manner The case is stained and
filled. II the wood requires it, then four or
five coats OF very thick varnish are put on
Five to ten DAYS are allowed between coats
depending on the varnish used Each coat
must be dry through. These coats are
called the bodying up coats After the
last one Is thoroughly dry, the case is
rubbed down with powdered pumice stone
and water. That is called coarse rubbing.
and the effect is a perfectly smooth sur
face.
The next step is q full-bodied coat Of
varnish; Il is called the flowing coat.
Plenty of time is allowed for this coat to
dry-ten days or two weeks
When it is sufficiently dry. It is rubbed
down to a flat. dead finish with pumlcs
and water. left one day. then rubbed again
with finely powdered rottenstone and water.
then polished with the bare hand. this po-
fishing can be done only by men OF ex-
perience who have hands suitable for the
work.
The result is a polish OF the most bril-
liant character, resulting from the several
coats Of varnish which have filled all the
minute crevices OF the wood with a trans
parent mass and which has been brought
70 a mirror-lke smoothness.
This polish Is particularly difficult to Sc
cure in permanent form. A number OF
bemishes may occur. the most common
being cross checking which is the name
/ for the countless tiny cracks which APP
pear on highly polished wood work Do not
confuse it with veneer checks or alligator
cracks The underlying is usually hardness
I and brittleness.
Z -H~a~AAANA AAAaA TINS NdTulHn necessarily
I dries very hard. Put a panel finished like
a piano in the cold and let it become thor
oughly chilled; strike the end of the panel
a sharp blow with a hammer. The beau
tifully polished surface will break. show
/ ing thousands OF tiny cracks Drop It on
the floor; the result viii be the same. Let
such panel become quite warm BY Ieav-
ing II In a room heated to eighty degrees
Take 1t at once 10 a temperature OF
/ freezing or below. The varnish does not
| contract with cold at exactly the same
rate as the wood. and the panel will prob
| ably cross check. IL viii do Il to a GER
tainty II 1t Is dropped, or II it receives
| any sudden shock. Let a sudden drauRht
of cold air strike a warm piano, IL will
crack, probably Sudden changes do the
harm Hot water poured into a cold
tumbler Will crack H.; ice cold water
poured into a warm tumbler will probably
crack it. The reason a piano cross checks
is the same reason that tumbler cracks.
Cross checking is the most common
trouble which comes to piano finish II
is the one trouble which can be guarded
against but it cannot always be pre-
vented.
There are other troubles Alligator
cracks. large irregular wavy cracks. due
TO too much varnish or too little time for
drying between coats. Veneer checks; the
veneer in its most beautiful burIs may
split In this case the crack follows the
pattern Of the grain exactly Veneer
checks cannot be guarded against The
risk is part OF the price OF beautiful wood
The trouble next in frequency to cross
checking, Is sinking in. Piano makers
in their effort 20 escape Cross checking NAV
use varnlsh that is too elastic. and as il
continues to oxidize long after the piano IL
shipped the polish dies away Countless
little depressiOna can be seen, as II the
wood was absorbing the life OF the varnish
Hence the name. sinking in" Where
sinking IN occurs the piano looks dun and
shabby TO every one who looks at Il, but
the polish can sometimes he restored with
I out another coat Of varnish.
] Il should be said that sinking in is some
! times caused by the use OF thin vsneers
] Tie very high cost OF fine veneers has
forced piano makers TO use veneers OF ex-
treme thinness. In open grained woods IL
is possible sometimes to see right through
| them. The glue and varnish sometimes
come directly into contact and II moisture
works through the wood and strikes the
glue Il softens the glue and that softena
l the vsrnish. This does not happen often
but IL does happen.
Another cause Of shrinking Ia the april
cation Of one coat Of varuish before the
coat beneath 10 thoroughly dry. Each coat
should be hard enough TO hold up the fol-
lowing coat before Il Is applied.
! In tho Wareroom. the softest possible
buster should be used. A feather duster
makes tiny scratches, and We recommend
a piece Of cheese cloth about a yard
square (cut it-dOn't tear ID. boiled 20
remove all sizing. Don't wash IL or
discard IL when il il sofled IL IS an the
better.
| II the vaTnish blooms the cause is damp
ness or lack Of ventilation. bloom h. the
name for the Opaque film which some
times forms over fine varnish. Fresh air
and sunlight may remove Il. but washing
may be necessary. II 30. a soft fine
sponge what 10 knoEn sometimes as a
baby sponge. with mkeWarm water. Wash
the piano carefully and ary n with the
right side Of a genuine chAmOis. soaked IN
water and Wrung out just s0 II viii not
drip; q little practice viii ave the trick
Most poliHhes Tor sale IN stores are IN
safe. vinegar or acid In them may eat
out the life Of the OIL and cause cracks
which vii not appear until months later.