Sometimes a fabrication shop will buy perforated metal for certain purposes. This is a raw material that comes already stamped with perforations. Such sheets are called perforated sheet, perforated plate, or perforated screen. The holes in the sheet are for various purposes, the most common being a way to reduce the overall weight of the sheet. Sometimes the perforations are purely for decorative purposes. Even when the perforations are for weight reduction, they are often done in a decorative manner, thereby accomplishing a structural need and increasing the beauty of a piece in the process.
This practice has been done for over 150 years. It began with using metal screen to separate coal. Those screens were perforated by hand-labourers. It was, however, and inconsistent and inefficient process, so new and increasingly-automated methods were developed over time.
Materials that are available in perforated metal sheets include stainless steel, cold rolled steel, galvanised steel, aluminium, tinplate, brass, copper, Monel, titanium, Iconel, and even plastic and other non-metal materials.
Modern methods employ machines and computers to create very complex and consistent perforations. Parkway Fabrications is a supplier of perforated metal sheet in the UK.
Applications of This
Architects use perforated sheets as infill panels, cladding, sunshades, signage, fencing, and more. The food and beverage industry uses them for drying grain, constructing beehives, sorting machines, and more. Chemical and energy companies use them to create centrifuges, battery separator plates, liquid gas burning tubes, gas purifiers, water screens and thousands or other applications. Material development finds them useful as well, employing them in glass reinforcement, dyeing machines, textile printers, felt mills, cinder and blast furnace screens etc. Automobile and automobile part manufacturers use them in air and oil filters, motorcycle silencers, ventilation grids, sand ladders and mats, running boards, flooring, radiator grilles, and more. They are also used widely in construction, for ceiling noise protection, stair treads, pipe guards, sun protection slats, sign boards, temporary parking and airfield surfaces, etc. These and many more industries use them every day, for a very wide variety of purposes.
One common use of perforated metal is to deaden sound, which helps to protect the hearing and health of those working in or near very noisy areas. These screens can also help to keep heat energy in, or block solar energy from overheating buildings in hotter climates. The effects can be quite profound.
A baluster, or spindle, is a moulded shaft, made of wood, metal or plastic, which stands on a unifying footing and supports the coping of a parapet or handrail. Sometimes this term is applied to a lathed shaft, such as a candlestick or similar component. They can be made of wood, plastic, metal, or other rigid material, and can be square, rectangular, or round in cross-section.
Many balusters in a row form a balustrade.
The OED lists ‘baluster’ as deriving from a description of the swelling form of a half-open pomegranate flower, which became βαλαύστιον (balaustion) in Greek, then moved through romance languages (particularly French and/or Italian) before arriving in common English usage.
The earliest extant examples of balusters are artistic depictions of them in Assyrian bas-reliefs, depicting Assyrian palaces. These show them used in windows, seemingly capped with Ionic capitals. Neither the Greeks nor Romans seem to have used them in architecture, but they are found as furniture components, as depicted in bas-reliefs. Used for tables, chairs, and lighting fixtures, these used stacked bulbs, discs, and ridges, and would have been made of marble or bronze, turned on a lathe. See our history here.
Their use in architecture was quite popular in the early Renaissance. You may recognise them in depictions of Juliet’s balcony, from the Shakespeare play. They may come from an earlier Gothic tradition, but examples confirming or disproving this have not yet been found.
Rudolf Wittkower refuses to make an official statement as to who the inventor of the baluster might have been, but credits Guiliano da Sangallo with some of the earliest consistent use in Italian architecture. The technique is used on the terrace and stairs at the Medici villa at Poggio a Caiano (around 1480). He also used balustrades in reconstructing antique architecture and structures. After Sangallo, balustrades were used by Bramante (Tempietto, 1502) and Michelangelo, who were instrumental in popularising them into the 16th century.
Changes in Style and Profiling
Even when formed in a mould, the design of balusters usually follows the heritage developed from being turned on a lathe. Even the lathe adopted design elements from its (probably) earlier cousin, the potter’s wheel. The result is usually a uniform, laterally-symmetric design. The particulars of an item’s design may suggest certain time periods or geographical areas, but this is not very reliable, as the choices of design created in this way are limited, and close similarities common.
One identifiable form is that of the Mannerist baluster, often described as a ‘vase set upon another vase’. Baroque traditions, likewise, favour high, thick shoulders and bold shapes. Neoclassic examples are described as more sober, resembling Greek amphorae. The English and Dutch furniture makers of the seventeenth century favoured twist-turned, or spiralling designs which resembled and were perhaps inspired by the Solomonic column as done by Bernini, which decreased in popularity after the early eighteenth century.
You can see some more famous metal structures here: https://www.shapecut.com.au/blog/8-famous-steel-structures/
Since lathed objects could then be split and used flat against a wall or other flat surface, they became popular in some architectural styles and in furniture making. Italian, Spanish, and Northern-European examples from the seventeenth century are numerous. Even the twentieth century saw a revival of the technique in the Arts and Crafts movement. Consider the exemplary row of houses, built around 1905, on Etchingham Park Road, in Finchley, London.
Ecclesiastical architecture also still shows examples of baluster shafts. The term is used to describe the dividing shaft in Saxon architecture. The south transept of the Abbey in St Albans, England, houses several examples, thought to have been recycled from the old Saxon church, combined with Norman bases and capitals, and placed alongside the plainer, cylindrical Norman shafts.
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