Fluorescent Tubes for Advertising Displays. Transparent and Translucent Materials

Every type of text and arbitrary line styles can be reproduced using fluorescent tubes, including ornamental and figured representations. Control is simple using rheostats or regulating transformers. Fluorescent tubes are commonly used for cinemas, theatres, sales advertising and publicity. In offices and businesses, louvred or gridded ceilings may be installed under fluorescent tubes to provide predominantly downward lighting – (1) – (5).

Strip-lights and elongated lighting panels allow soft uniform lighting to be achieved, which approximates daylight and has shadow effects.

High-pressure mercury vapour lamps with fluorescent gas are used for the illumination of factories and workshops as well as for external lighting.

Mixed-light lamps with fluorescent gas produce light similar to daylight, with good colour reproduction. These lamps have standard fittings, without a ballast device (e.g. general-purpose lamps).

Transparent and Translucent Materials. In determining the size, colour, window dimensions and lighting of a room, a knowledge of the translucence, scatter and reflected radiation of the materials to be used in the room is required. This is particularly important for effective artistic and economic design.

A distinction is made between materials which reflect light - (9) with direct, totally scattered or partially scattered return radiation, and translucent materials with direct - (1) – (6), scattered – (7) or mixed translucence - (8).

Note: Frosted glass with inside surface frosting (preferred owing to fewer soiling problems) absorbs less light than the same glass with external surface frosting - (9).

Coloured silk lampshades with white linings which minimally reduce translucence absorb around 20% less light than those without linings and with greater translucence.

Daylight glass which filters electric light to simulate sunlight absorbs approximately 35% of the total light. Glass which comes close to copying the scattered light of the sky must absorb 60-80%.

Clear window glass is translucent to between 65 and 95% of light. If poor-quality clear glass is used, particularly in the case of double or triple glazing, so much light is absorbed that it is necessary to increase the window size. This increase is not compensated for by the improved thermal insulation of the multi-paned window assembly.

Sheet glass is made mechanically, and is ready for use without further processing. It is a clear, transparent glass which is colourless and uniformly thick. Both sides have even plane surfaces, and its transparency to light is 91-93%.

Classification:
Type 1: Best commercial quality product for rooms (living accommodation, offices).
Type 2: Structural glass for factories, storerooms, cellars and glass floors.

Glass of one type only should be used for glazed items which are sited next to each other. Such applications include window glazing, shop windows, doors, dividing walls, furniture construction, laminated safety glass and double-glazing units. Further processing might entail polishing, etching, frosting, stoving, silvering, painting, bending or arching. Special-purpose glass, such as silvered glass, dry plate glass, glass for automobiles and safety glass, is made in all thicknesses.

General requirements for daylight illumination of internal areas. All rooms which are to be used for permanent occupation must be provided with adequate natural light. In addition, appropriate visual links with the outside world must be safeguarded.

Light, wavelength, light colour. Within the electromagnetic spectrum - (1), visible light occupies a relatively small band, namely 380-780nm. Light (daylight and artificial light) is the visible band of electromagnetic radiation between ultra-violet and infrared.

The spectral colours which occur in this range each have corresponding wavelengths, e.g. violet is short wave and red is long wave. Sunlight contains relatively more short-wave radiation than a filament lamp, which has more long-wave radiation, i.e. a greater red light component. However, daylight is perceived by the human eye as being white, apart from at sunrise and sunset, when it appears red.

The unit of measurement for illuminance (particularly artificial light) is the lux (lx). The level of daylight in rooms is given as a percentage (see later).