A Grate Architectural Invention

Most commonly seen as a metal grille studded with diamond
shaped holes, expanded metal is a versatile tool used for many industrial and
architectural purposes. It has been around since the late 19^th
century, after being developed via the method devised in Hartlepool in 1880,
and which is still used today despite the surrounding technological advances.

The process begins with solid sheet metal, which will be
transformed into a significantly larger area of expanded metal and very little
is wasted. The sheet is fed into the expanding machine whereby the metal is cut
by a “knife” in the form of a horizontal blade with sharp teeth which stamp
down through the metal, moving from side to side to create the familiar lattice
pattern. The teeth are shaped like upside down pyramids which enable them to
stretch the diamond shape holes, thus enlarging the metal by degrees. The end
product of this manufacturing process is usually rolled into sheets which can
be cut for purpose at a later time. Most metals can be expanded which means
that the appropriate material can be chosen depending on its final use.

Owing to its many useful properties, including durability,
transparency, high airflow and easy installation, expanded metal is used globally
for a variety of applications. These features also demonstrate why it remains
both a practical and ornamental solution to architectural design in industry
and at home, whether required internally for walkways and stairwells or externally
as metal cladding or balcony balustrades. Expanded metal is famously used on
the trusty London train bench, where unsuspecting travellers sit for a while
and leave with diamonds printed on the backs of their legs. These benches are
often painted to suit their surroundings and disguise their industrial origins.
Put to more architectural use, this metal cladding  has been the basis of a
designer detention centre in Holland. The Juvenile Pavilion in Overloon aims to
connect offending youths with nature through the open style created by the
transparent expanded metal. This design also reduces the appearance of
permanence which solid walls would represent, enabling the youngsters to see
their future in the outside world.

Unfortunately, the strong association of metal grills with
security is reinforced in some towns where window guards are installed to
protect residents from vandals and burglars, while many school playgrounds are
surrounded by a tall perimeter of fencing. However, other practical uses include
air conditioning grills, reinforced concrete, industrial straining devices,
shelving and furniture besides featuring in modern artistic installations
displayed upon walls and in gardens. 

Emily Banham is construction blogging enthusiast from south east England.