|
Mimeograph Machine
A mimeograph machine (often abbreviated to mimeo, sometimes called a stencil duplicator) is a low-cost duplicating machine that works by forcing ink through a stencil onto paper. The process is called mimeography, and a copy made by the process is a mimeograph. Mimeographs, along with spirit duplicators and hectographs, were common technologies for printing small quantities of a document, as in office work, classroom materials, and church bulletins. Early fanzines were printed by mimeograph because the machines and supplies were widely available and inexpensive. Beginning in the late 1960s and continuing into the 1970s, photocopying gradually displaced mimeographs, spirit duplicators, and hectographs. For even smaller quantities, up to about five, a typist would use carbon paper. Origins Use of stencils is an ancient art, butthrough chemistry, papers, and pressestechniques advanced rapidly in the late nineteenth century: Papyrograph A description of the Papyrograph method ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spirit Duplicator
A spirit duplicator (also referred to as a Rexograph or Ditto machine in North America, Banda machine in the UK, Gestetner machine in Australia) is a printing method invented in 1923 by Wilhelm Ritzerfeld that was commonly used for much of the rest of the 20th century. The term "spirit duplicator" refers to the alcohols that were a major component of the solvents used as "inks" in these machines. The device coexisted alongside the mimeograph. Spirit duplicators were used mainly by schools, churches, clubs, and other small organizations, such as in the production of fanzines, because of the limited number of copies one could make from an original, along with the low cost (and corresponding low quality) of copying. History The spirit duplicator was invented in 1923 by Wilhelm Ritzerfeld. The best-known manufacturer in the United States and the world was Ditto Corporation of Illinois. Copiers in the United Kingdom were commonly manufactured by Associated Automation Ltd of Will ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Belgian Resistance
The Belgian Resistance (french: Résistance belge, nl, Belgisch verzet) collectively refers to the resistance movements opposed to the German occupation of Belgium during World War II. Within Belgium, resistance was fragmented between many separate organizations, divided by region and political stances. The resistance included both men and women from both Walloon and Flemish parts of the country. Aside from sabotage of military infrastructure in the country and assassinations of collaborators, these groups also published large numbers of underground newspapers, gathered intelligence and maintained various escape networks that helped Allied airmen trapped behind enemy lines escape from German-occupied Europe. During the war, it is estimated that approximately five percent of the national population were involved in some form of resistance activity, while some estimates put the number of resistance members killed at over 19,000; roughly 25 percent of its "active" members.Henri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halftone
Halftone is the reprographic technique that simulates continuous-tone imagery through the use of dots, varying either in size or in spacing, thus generating a gradient-like effect.Campbell, Alastair. The Designer's Lexicon. ©2000 Chronicle, San Francisco. "Halftone" can also be used to refer specifically to the image that is produced by this process. Where continuous-tone imagery contains an infinite range of colors or greys, the halftone process reduces visual reproductions to an image that is printed with only one color of ink, in dots of differing size ( pulse-width modulation) or spacing (frequency modulation) or both. This reproduction relies on a basic optical illusion: when the halftone dots are small, the human eye interprets the patterned areas as if they were smooth tones. At a microscopic level, developed black-and-white photographic film also consists of only two colors, and not an infinite range of continuous tones. For details, see film grain. Just as color p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ozone
Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lower atmosphere to (dioxygen). Ozone is formed from dioxygen by the action of ultraviolet (UV) light and electrical discharges within the Earth's atmosphere. It is present in very low concentrations throughout the latter, with its highest concentration high in the ozone layer of the stratosphere, which absorbs most of the Sun's ultraviolet (UV) radiation. Ozone's odour is reminiscent of chlorine, and detectable by many people at concentrations of as little as in air. Ozone's O3 structure was determined in 1865. The molecule was later proven to have a bent structure and to be weakly diamagnetic. In standard conditions, ozone is a pale blue gas that condenses at cryogenic temperatures to a dark blue liquid and finally a violet-black ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Spark
An electric spark is an abrupt electrical discharge that occurs when a sufficiently high electric field creates an ionized, electrically conductive channel through a normally-insulating medium, often air or other gases or gas mixtures. Michael Faraday described this phenomenon as "the beautiful flash of light attending the discharge of common electricity". The rapid transition from a non-conducting to a conductive state produces a brief emission of light and a sharp crack or snapping sound. A spark is created when the applied electric field exceeds the dielectric breakdown strength of the intervening medium. For air, the breakdown strength is about 30 kV/cm at sea level. Experimentally, this figure tends to differ depending upon humidity, atmospheric pressure, shape of electrodes (needle and ground-plane, hemispherical etc.) and the corresponding spacing between them and even the type of waveform, whether sinusoidal or cosine-rectangular. At the beginning stages, free electrons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermofax
Thermo-Fax (very often Thermo fax) is 3M's trademarked name for a photocopying technology which was introduced in 1950. It was a form of thermographic printing and an example of a dry silver process. It was a significant advance as no chemicals were required, other than those contained in the copy paper itself. A thin sheet of heat sensitive copy paper was placed on the original document to be copied, and exposed to infrared energy. Wherever the image on the original paper contained carbon, the image absorbed the infrared energy when heated. The heated image then transferred the heat to the heat sensitive paper producing a blackened copy image of the original. Model 12 The first commercially available Thermofax machine was the Model 12. The 'layup' of the original and the copy paper was placed on a stationary glass platen and an infrared lamp and reflector assembly moved beneath the glass, radiating upwards. The layup was held in position by a lid with an inflatable rubber bladde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Correction Fluid
A correction fluid is an opaque, usually white fluid applied to paper to mask errors in text. Once dried, it can be handwritten or typed upon. It is typically packaged in small bottles, lids attached to brushes (or triangular pieces of foam) that dip into the fluid. The brush applies the fluid to the paper. Before the invention of word processors, correction fluid greatly facilitated the production of typewritten documents. One of the first forms of correction fluid was invented in 1956 by American secretary Bette Nesmith Graham, founder of Liquid Paper. With the advent of colored paper stocks for office use, manufacturers began producing their fluids in various matching colors, particularly reds, blues and yellows. Composition The exact composition of correction fluid varies between manufacturers, but most fluids are composed of an ''opacifying agent'', a ''solvent'' (or thinner) and an adulterant 'fragrance' to discourage abuse. The opacifying agent can be composed of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Styluses
A stylus (plural styli or styluses) is a writing utensil or a small tool for some other form of marking or shaping, for example, in pottery. It can also be a computer accessory that is used to assist in navigating or providing more precision when using touchscreens. It usually refers to a narrow elongated staff, similar to a modern ballpoint pen. Many styluses are heavily curved to be held more easily. Another widely used writing tool is the stylus used by blind users in conjunction with the slate for punching out the dots in Braille. Etymology The English word ''stylus'' has two plurals: ''styli'' and ''styluses''. The original Latin word was spelled ; the spelling ''stylus'' arose from an erroneous connection with Greek (), 'pillar'.''Oxford Latin Dictionary'', s.v. "stilus" (2012). The Latin word had several meanings, including "a long, sharply pointed piece of metal; the stem of a plant; a pointed instrument for incising letters; the stylus (as used in literary compo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mineral Oil
Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils. The name 'mineral oil' by itself is imprecise, having been used for many specific oils over the past few centuries. Other names, similarly imprecise, include 'white oil', 'paraffin oil', ' liquid paraffin' (a highly refined medical grade), (Latin), and 'liquid petroleum'. Most often, mineral oil is a liquid by-product of refining crude oil to make gasoline and other petroleum products. This type of mineral oil is a transparent, colorless oil, composed mainly of alkanes and cycloalkanes, related to petroleum jelly. It has a density of around . Nomenclature Some of the imprecision in the definition of the names used for mineral oil (such as 'white oil') reflects usage by consumers and merchants who did not know, and usually had no need of knowing, the oil's precise chemical mak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Typewriter Ribbon
A typewriter ribbon or ink ribbon is an expendable module serving the function of transferring pigment to paper in various devices for impact printing. Such ribbons are part of standard designs for hand- or motor-driven typewriters, teleprinters, stenotype machines, computer-driven printers and many mechanical calculators. The module consists of a length of a medium, either pigment-impregnated woven ribbon or pigment-coated polymer tape, and a transport mechanism involving two axles. At any given moment, most of the length of the medium is wound as a close-spaced spiral around one axle or the other, tight enough for friction among turns to make it behave mostly like a solid cylinder. Rotation of the axles moves the ribbon or tape after each impact and usually aids in maintaining tension along the roughly straight-line path of the medium between the axles. The module may itself include mechanisms that control the tension in the temporarily unwound portion of the medium. Some type ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Castor Oil
Castor oil is a vegetable oil pressed from castor beans. It is a colourless or pale yellow liquid with a distinct taste and odor. Its boiling point is and its density is 0.961 g/cm3. It includes a mixture of triglycerides in which about 90% of fatty acids are ricinoleates. Oleic acid and linoleic acid are the other significant components. Castor oil and its derivatives are used in the manufacturing of soaps, lubricants, hydraulic and brake fluids, paints, dyes, coatings, inks, cold-resistant plastics, waxes and polishes, nylon, and perfumes. Etymology The name probably comes from a confusion between the '' Ricinus'' plant that produces it and another plant, the '' Vitex agnus-castus''. An alternative etymology, though, suggests that it was used as a replacement for castoreum. Composition Castor oil is well known as a source of ricinoleic acid, a monounsaturated, 18-carbon fatty acid. Among fatty acids, ricinoleic acid is unusual in that it has a hydroxyl functiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
