architectural
specifications:
general information for architects
| architectural data | examples
of metal colors available
general
information for architects
| brass |
In its
basic form Brass is an alloy of copper and zinc, but most alloys
contain additional elements. For architectural purposes Brasses
are widely used, however the building industry commonly refers to
some of these alloys as Bronze; although it is a misnomer, it is
accepted practice. |
| bronze |
In its
basic form Bronze is an alloy of copper and tin. In architectural
applications true bronze is rarely used. |
| nickel
silver |
In its
basic form Nickel Silver is an alloy of copper, nickel and zinc,
which has a warm silver appearance. |
|
Copper
alloys possess different properties and as a result have varied
uses. Some alloys are used for casting, some for extrusion and hot
forging, and others for sheet and strip manufacture. |
|
Across
the range of alloys, a number are used for manufacture in more than
one condition; for example, a given alloy may be capable of being
used for both casting and extension. |
|
The
most important thing for an architect to know is that the appropriate
use of Brass and Bronze alloys can result in an over-all color matching
system. |
| mechanical |
(i)
Screws, belts, rivets.
(ii) Extensions can be custom designed
to incorporate a snapÜ or šslideÜ fit to loin various shapes
|
| adhesive |
Sheets
laminating to steel, plywood or similar substrate. (See also Dissimilar
Metals). Brass and Bronze can also be adhered to itself if intersecting
members are mechanically aligned, for example with a sleeve and
locking pins. |
| metallurgical |
(i) Brazing
A medium temperature joining method involving the melting of the
filler material without melting the base material. Because color
matching of brazed fillers is difficult, brazing is best done with
blind or concealed joints. Brazing is the preferred metallurgical
joining method as it does not distort the base material.
(ii) Soldering
A low temperature joining method used for sealing joints which
does not result in a strong bend and is therefore best used in
conjunction with mechanical fasteners.
(iii) Welding
A high temperature joining method which fuses base materials,
but is generally not used for architectural work because of color
matching and joint distortion problems.
|
|
Brasses
and Bronzes should not be used in contact with steel or aluminum
as this tends to accelerate corrosion of the steel and aluminum.
When the two metals do adjoin they should be separated by some form
of insulating material, for example neoprene, felt or a bituminous
coating. With mechanical joining of dissimilar metals, stainless
steel fasteners are recommended. |
| as
manufactured |
The finishes
imparted by normal production of extrusions, forgings. castings,
etc. |
| buffed |
A process
of grinding, polishing and buffing. Finishes range from low luster
polish to smooth mirror finish. |
| directional
textured |
The most
common finish on architectural shapes. This finish is produced by
polishing of the surface with near parallel lines, resulting in
a smooth, velvety appearance often referred to as šsatin finishÜ. |
| non-directional
textured |
Matte
finishes of varying degrees of abrasion. |
| patterned |
A combination
of textural finishes, often referred to as embossingÜ or šcoiningÜ. |
| general |
The characteristic
colors of Architectural Brass, Bronze and Nickel Silver in their
As-Manufactured, Polished and Chemically Colored states are tabulated
on page 31.
Most Brass and Bronze alloys have
a GOLDEN HONEY color in their natural state and a RICH STATUARY
BRONZE in their chemically colored state. Brasses which contain
aluminum exhibit a BRIGHT YELLOW coloring in their as-manufactured
state, but the color changes to HONEY when polished. PINK Brass
and Nickel Silver are also available when alternative coloring
is required.
|
| natural
color |
Natural
honey colored Brass & Bronze is as the name suggests, however
the difficulty with it lies in the tact that, given enough time,
it will weather to a brown color. Obviously, this occurs more rapidly
when it is exposed to weather. The rate of weathering depends on
the degree of humidity, and the level of pollutants in the air.
A greater problem occurs with fingerprints. Acids from the body
leave marks on the natural Brass & Bronze, and for this reason
natural honey Brass & Bronze needs to be protected, either by
coating, or by cleaning and/or polishing regularly if it is handled
constantly, as in the case of handrails and door furniture. |
| chemical
coloring |
Chemical
coloring is a process with great dependence on the experience of
the craftsman. In general, all types of chemical coloring artificially
weather the Brass or Bronze from its natural color to a darker color.
This is accomplished by converting the surface of the metal into
a colored protective film, using an oxide or a sulfide.
For architectural use, chemical coloring is used to achieve a
šstatuaryÜ finish (i.e. a medium to dark brown appearance) through
either of two methods. The first method is to dip the material
in a chemical bath and is practical for small pieces. The second
method is to brush on and wipe of f one of the several available
chemicals. This is more appropriate for larger pieces and can
be performed in the factory or in situ.
It is sometimes impractical, costly
and unnecessary to have a finisher handle every piece of Brass
or Bronze, however the talents of a craftsman should be used when:
(i)The Brass or Bronze piece
in question cannot be readily immersed in a chemical bath.
(ii) Precise color matching
of separate pieces is made necessary by immediate adjacency.
(iii) The surface area of Brass
& Bronze pieces is sufficient to require an even-handed
wrought appearance
(iv) Special circumstances of
manufacture and/or delivery of Brass & Bronze makes hand-finishing
the only choice.
Examples of fittings which may
require hand coloring are:
(i) Status Door Pulls
(ii) Special Extrusion Doors
and Frames
(iii) Lift Entrances and Cabs
(iv) Timber/Bronze Doors
Chemically colored Brass &
Bronze should be maintained and protected by the repeated application
of oil or wax (linseed, lemon and paraffin oils are commonly used).
The frequency of oiling will decrease over time as layers of oil
build up to create a protective surface and result in what is
known as oil rubbed bronzeÜ.
When a piece of oil rubbed Brass
or Bronze is repeatedly touched, as with door knobs, the oil and
colored surface wear through to the natural base color.
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