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All about brass - by Laura
Evans
Brass is a type of metal
alloy made from a combination of copper and zinc.
Alpha brasses contain less than 35% zinc. This makes the
resulting bronze relatively easy to work even when the
brass is cold. Alpha-beta's zinc content is 35% to 45%
zinc. This type of brass can be worked when hot. Beta
brass, consisting of 45% to 50% zinc, should only be
worked when hot. Beta brasses are stronger and harder
than alpha or alpha-beta brasses. White brass is more
than 50% zinc. It is very brittle and not generally
used.
Today, brass is made by combining copper and zinc. In
ancient times, no one knew what zinc was. However,
ancients were able to find calamine, a zinc ore. They
used calamine in combination with copper to make brass.
The Greeks called brass "oreichalcos"
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the
Romans called it "aurichalum." Romans used brass for their
helmets and jewelry.
Before the 1700's, zinc could not be found or taken in its pure
form because the technology did not yet exist that could
melt it. Zinc's melting point is 420 degrees Centigrade. In
order to make brass, ground calamine ore and copper were mixed
together and then heated in a crucible. This did not melt the
copper, but it did release vapors from the zinc in the calamine
into the copper. After zinc vapors permeated the copper, brass
was formed. The brass was then melted down to make the metal
uniform.
In 1746, zinc was isolated by Andreas Marggraf.
Brass is used in many products today like brass art, handicraft,
casting and very often for religious items,
 in
particular Buddha sculptures, images and figures like this
sitting Buddha in the left picture. It is used for both
decorative and practical purposes in drawer pulls, latches,
handles and knobs. Brass is made into brass instruments,
including the trumpet. It is used to make candlesticks,
fireplace accessories, telescopes and weathervanes. Brass is a
very versatile metal alloy.
Brass in its natural state tarnishes when exposed to oxygen,
unless the it is covered with a protective lacquer. Regardless
of whether you brass is protected or "raw," do not try to clean
it with any type of abrasive material. If the piece that you are
cleaning is an antique, make sure you test the cleaning product
that you are planning to use in an unobtrusive area on the brass
before you start. You will want to make sure your cleaner does
not remove the results of natural aging from your antique. If
your piece is very old and not in the best condition, you might
consider consulting an expert at your local museum for cleaning
instructions.
Chinese cloisonne - antique
vases
by Beatrice Quette
The
Musee des Arts decorative in Paris has one of the world's best
collections of Chinese cloisonne made between the
beginning of the fifteenth and the beginning of the twentieth
centuries. Cloisonne was first described in China in 1388 by Cao
Zhao in his Ge gu yao lun (Essential Criteria of Antiquities):
The base of this ware is of copper, and designs an it are in
five colours, made with chemicals and fired. It is similar to
the Fo-lang-k'an (enamel ware). I have seen pieces such as
incense-burners, flower vases, boxes, and cups, which are
appropriate for use [only] in a woman's apartment, and would be
quite out of place in a scholar's studio. It is also known as
Ware from the Devil's Country (Kuei-kuo yao).(1)
The devil's country comprised the countries situated to the
west of China. The technique of making cloisonne was
probably imported from Byzantium, reaching China at the end of
the fourteenth century. This theory has been reinforced by the
technical analysis of fifteenth- and sixteenth-century examples
from the museum's collection by the Laboratoire de recherche des
musees de France.(2) These tests found that in composition and
manufacture the Chinese cloisonne is close to its Byzantine
counterpart.
In China the bodies of the
vases and tripods were cast of brass in shapes inherited from
the Bronze Age,
whereas
plates, dishes, bowls, and decorative panels were made of sheet
brass in the fifteenth and sixteenth centuries and of copper by
the end of the Ming dynasty (1368-1644). The decorative design
was drawn on the vessel with ink, and thin metal ribbons were
soldered perpendicularly to the surface, following the inked
lines. During the Ming dynasty the ribbons were made by
hammering sheet metal, which explains their frequently irregular
thickness.
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After the seventeenth century ribbons were make by
rolling out the metal between two metal cylinders, which
ensured a uniform thickness. The ribbons are always of
the same metal as the body and are generally one or two
millimeters high. The powdered enamel colors were mixed
with water and probably some kind of glue to form a
paste that was then used to fill the cells left by the
soldered metal ribbons. When the enamel colors had
dried, the object was fired in a muffle kiln at 700 to
800 degrees centigrade. This had the effect of reducing
the level of the enamels, |
so the process was
repeated until all the cells were full. The resulting irregular
surface was polished, leaving a dull sheen, and the exposed
metal, including the top edge of the ribbons forming the cells,
was gilded. |
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Brass,
brass knuckles,
brass bed,
brass model,
brass knuckle,
brass eagle,
brass rail,
brass bells,
brass hardware,
copper and brass,
antique brass,
brass lamp,
brass chandelier,
brass strip,
big brass bed,
brass lantern,
brass tubing,
brass, handles, brass trains, brass
construction, India brass, brass table lamp, brass
candle holder, brass door knocker, brass pole, antique
brass bed, brass ball, brass plate, brass knob, brass
grommets, brass craft, brass elephant, brass hinge,
brass refinishing, brass metal, brass oil lamp brass
buckle, brass tube, brass sculpture, brass screw, brass
key, brass door knob, brass plum. |
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BRASS ART HANDICRAFT and CASTING |
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