The evening times. [volume] (Washington, D.C.) 1895-1902, 1901-07-15
THE BRONZE POWDER BUSINESS
This Industry Thoroughly Described
by an American Consul.

says:
one of the most important and inter
eStiEg of the special forms of manufac-
tUTc, for the product Of which tho United
States is dependent upon Germany Is that
of bronze powder the shining metallic
dust which is used for producing gilt and
bronze effects in wall papers. lettcTpTG-s
printing, photography mirror and picture
frames, fTesCO painting and the artistic
decoration of a vast range Of manufaC-
turcd articles in wood. paper, and vari-
Gus metals. For all these purposes.
bronze powder offers the cheapest and
most effective means of giving 4 surface
effect Of gilt or bronze. and its use has
expanded with the rapidly increased pro-
ductton OF articles Of luxury and taste
The principal seat Of the bronze pow
der manufacture is the city and vicinity
of Furth- in Bavaria. where the requisite
water power and other conditions are fav-
orabie, and the industry is in the hands
of an exceptionally intelligent and enter
prisinS class OF men, who have invented
new machinery and improved methods
until the whole process of manufacture is
now mature, ably mana ged, and success
ful- The material used is so-called Dutch
metal, an alloy Of copper and spelter in
which the relative proportions of
these are varied to produce the
different coIors desired The larger
the percentage of speIter. the light
er or more yelIowish viii be the tint
OF the alloy The manufacturing process
divides itself into two stages or branches,
which are usually carried on in different
establishments, namely, the preparation
of leaf metal and the reduction of Clip
pings of that material to the form of
hr- mil
The copper and spelter are smelted to-
gether in graphite crucibIes. which are
inserted in a large furnace heated by
strong coke FIRE. The crUCibles contain
about 400 pounds of metal, and when their
contents are completely fused, they are
run off into moids, which form half-round
ingOts two feet long by half an inch in
thickness. After cooling. these ingots OF
rods are bound into bundles and sent to
the rolling mill, where they are passed
cold nine times through a double set Of
steel rolls unoer powerful pressure. by
which they are fatteued and drawn out
into thin ribbons from fifty to sixty feet
in length and something more than one
inch n width. Cold rolling under such
extreme pressure has the effect Of render
ing the metal brittle, ard it therefore
passes at this stage to the anneaIing fur
sulphur in coal or coke would be injuri-
Gus to the ribbons. which, having been
sOftened and rendered ductiIe by anneaI-
ing. are cleansed IN an acid bath cut into
lengths of about three feet. and collected
in bundles OF forty or fifty strips each
They are now laid between sheets Of zinc,
which are fastened together and passed
under singing hammers worked by water
or STAN power. by which the metal
strips are beaten to thickness of tissue
paper This process includes six success
Sive Beaunss, AID requires great skill on
:he part OF the operatives to produce a
uniform and unbrOken foil After the
third beating the metal strips are taken
from between the sheets of zinc EooscneG
from each others ana cIeansed by INNER
sion in a bath Of tartrate Of potassium
This cleaning is repeated after the sixth
and last beating. and the sheets. thus
cleansed from oxide and other impurities
are hung upon lines to dry At the begin
ming the rolled strips are of q dull grey
metallic color; at the fourth beating the
yeiIowish color begins TO show. and after
the sixth they are clear and bright 3s
gold
In view OF the great variety Of puT-
poses for which bronze powder is employ
ed, it is graded in respect to color into
. bright copper ed to golden yellow These
successive tfntS are governed by the rela-
tive proportions OF copper and Spelter
used IN making alloy. which are as fol-
lows No !, $50 parts copper. IS parts
speiter; No.r1iz. $50 parts copper, - parts
sDelteT: No. =, 33D parts copper. 81 parts
spelteri No. ,, 80 parts copper, 20 parts
sDelter; No !. SO parts copper, 90 parts
spelter1 No T. 800 parts copper, ~ parts
IN the foregoing description. the ma
Z bod Of
sheets OF leaf metal. three feet in length.
widened by hammering between zinc
plates one inch to an average width OF
eight inches These, having been cleaned
and dried, are carefully assorted. the de
fectIve leaves thrown out as waste or in
ferioT material, and the perfect ones cut
into small squares, which are laid togeth-
CT by hand in packets Of several hun
T dred each and inclOSed within an envelope
. Of sheet brass. Thus held together and
protected. the packets are returned TO the
aBnealiHg furnace, where they are soft
ened by heating and slow cooling. and
then 20 to the beateTs where they are re
duced. under faJteniHs hammers. TO the
thinneSs OF real gold IeaT-SO thin that il
can be blown away by the brea h This
completes the preparation of leaf metal.
the finished material for bronze powder
and other purposes. Of which there are
not less than a hundred manufacturers in
the city and district Of FuTth. This part
Of the industry dates from the sixteenth
century, and has been built up by many
generations of patient and SkiIlful beat
( ers of gold. silver, copper and other mai
I leahle metals.
The manufacture Of bronze powder
consists in grading. clipping, and puiver-
I iZiBg the various bronze fOilS to an even.
imDalpabie powder. and is an industry Of
! comparatively recent date. The present
/ perfection Of methods and product has
only been attained during the past thirty
years II began as a means Of using up
and utilizing the imperfect leaves which
came as waste from the beateTs Of gold.
( silver, and bronze These Were cut by
hand into fine clippings and then ground
/ to powder in handmillS Of simple con
I StruCtiOn- With the lapse OF time and the
/ spread of artistic indL tries. the uses of
/ bronze powder increased until the demand
( far OutTau the supply Of waste, and the
/ leaf metal is now made on a large scale
/ specially as a material for this purpose
The beating process hatteuS out "A pound
/ of copper and spelter alloy TO area Of
( about 5Gu square feet and in this cOndi-
/ tiou the square sheets. rs they come from
/ the brass envelopes, are ShcareG into
/ small fragments and rubbed with olive
( oil through a steel sieve having ten
I Yueshes 20 the inch, and then passed to
} the stamping and grinding machines.
( where they are pUlveriZed by steam or
water power 10 the bronze powder Of com
/ mrTCC-
/ The grinding occupies from one to
! four hours. according 20 the grade uT
/ quality of the powder to be produced.
1 which IS Of four Srades-from coarse to
SupfItiGe. The SupeTtiuouS OIL Is removed
I by heating under pressure. and the pow
der is then carried into centrifugal cIari-
{ fierS, or grading machines. which. turn
ing at a high speed, eXpel the powder
through fine 0rihces in the form Of dust.
which settles on enclosed shelves. accord
( ing to the weight and finencss-the finer
( and iE this way the powder is divided in
To the several grades Of hneneSs and con