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Lampworking
Lampworking is a type of glasswork in which a torch or lamp is used to melt the glass. Once in a molten state, the glass is formed by blowing and shaping with tools and hand movements. It is also known as flameworking or torchworking, as the modern practice no longer uses oil-fueled lamps. Although lack of a precise definition for lampworking makes it difficult to determine when this technique was first developed, the earliest verifiable lampworked glass is probably a collection of beads thought to date to the fifth century BC. Lampworking became widely practiced in Murano, Italy in the 14th century. As early as the 17th century, itinerant glassworkers demonstrated lampworking to the public. In the mid-19th century lampwork technique was extended to the production of paperweights, primarily in France, where it became a popular art form, still collected today. Lampworking differs from glassblowing in that glassblowing uses a furnace as the primary heat source, although torches are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Borosilicate Glass
Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glasses are known for having very low coefficients of thermal expansion (≈3 × 10−6 K−1 at 20 °C), making them more resistant to thermal shock than any other common glass. Such glass is subjected to less thermal stress and can withstand temperature differentials without fracturing of about . It is commonly used for the construction of reagent bottles and flasks as well as lighting, electronics, and cookware. Borosilicate glass is sold under various trade names, including Borosil, Duran, Pyrex, Glassco, Supertek, Suprax, Simax, Bellco, Marinex (Brazil), BSA 60, BSC 51 (by NIPRO), Heatex, Endural, Schott, Refmex, Kimax, Gemstone Well, and MG (India). Single ended self-starting lamps are insulated with a mica disc and contained in a borosilicate glass gas discharge tube (arc tube) and a metal cap. They include the sodium-vapor la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glassblowing
Glassblowing is a glassforming technique that involves inflating molten glass into a bubble (or parison) with the aid of a blowpipe (or blow tube). A person who blows glass is called a ''glassblower'', ''glassmith'', or ''gaffer''. A ''lampworker'' (often also called a glassblower or glassworker) manipulates glass with the use of a torch on a smaller scale, such as in producing precision laboratory glassware out of borosilicate glass. Technology Principles As a novel glass forming technique created in the middle of the 1st century BC, glassblowing exploited a working property of glass that was previously unknown to glassworkers; inflation, which is the expansion of a molten blob of glass by introducing a small amount of air into it. That is based on the liquid structure of glass where the atoms are held together by strong chemical bonds in a disordered and random network,Frank, S 1982. Glass and Archaeology. Academic Press: London. Freestone, I. (1991). "Looking into Glass". I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen Concentrator
An oxygen concentrator is a device that concentrates the oxygen from a gas supply (typically ambient air) by selectively removing nitrogen to supply an oxygen-enriched product gas stream. They are used industrially and as medical devices for oxygen therapy. Two methods in common use are pressure swing adsorption and membrane gas separation. Pressure swing adsorption ( PSA) concentrators utilize multiple molecular sieves consisting of zeolite minerals that adsorbs pressurized nitrogen in fast cycles. History Home medical oxygen concentrators were invented in the early 1970s, with the manufacturing output of these devices increasing in the late 1970s. Union Carbide Corporation and Bendix Corporation were both early manufacturers. Before that era, home medical oxygen therapy required the use of heavy high-pressure oxygen cylinders or small cryogenic liquid oxygen systems. Both of these delivery systems required frequent home visits by suppliers to replenish oxygen supplies. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead Glass
Lead glass, commonly called crystal, is a variety of glass in which lead replaces the calcium content of a typical potash glass. Lead glass contains typically 18–40% (by weight) lead(II) oxide (PbO), while modern lead crystal, historically also known as flint glass due to the original silica source, contains a minimum of 24% PbO. Lead glass is often desirable for a variety of uses due to its clarity. The term ''lead crystal'' is, technically, not an accurate term to describe lead glass, because glass lacks a crystalline structure and is instead an amorphous solid. The use of the term ''lead crystal'' or just "crystal" remains popular for historical and commercial reasons, and because "lead" sounds toxic to consumers. It is retained from the Venetian word ''cristallo'' to describe the rock crystal imitated by Murano glassmakers. This naming convention has been maintained to the present day to describe decorative hollow-ware. Lead crystal glassware was formerly used to st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annealing (glass)
Annealing is a process of slowly cooling hot glass objects after they have been formed, to relieve residual internal stresses introduced during manufacture. Especially for smaller, simpler objects, annealing may be incidental to the process of manufacture, but in larger or more complex products it commonly demands a special process of annealing in a temperature-controlled kiln known as a lehr.E. F. Collins (1921) Electrically heated glass annealing lehr. Journal of the American Ceramic Society 4 (5), pp. 335–349 Annealing of glass is critical to its durability. Glass that has not been properly annealed retains thermal stresses caused by quenching, which will indefinitely decrease the strength and reliability of the product. Inadequately annealed glass is likely to crack or shatter when subjected to relatively small temperature changes or to mechanical shock or stress. It even may fail spontaneously. To anneal glass, it is necessary to heat it to its annealing temperature, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidizing And Reducing Flames
In pyrology, flames are affected by the fuel introduced and the oxygen available. A flame with a good oxygen-fuel ratio is called a neutral flame. The color of the flame is semi-transparent purple or blue. This flame is optimal for all intentions, because it does not oxidize or get soot onto surfaces. Oxidizing flame If the flame has too much oxygen, an oxidizing flame is produced. When the amount of oxygen increases, the flame shortens due to quicker combustion, its color becomes a more transparent blue, and it hisses/roars."The Anatomy of a Flame" in: "Jewelry concepts and technology", by Oppi Untracht, 1983, With some exceptions (e.g., platinum |
Tungsten
Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite and wolframite, the latter lending the element its alternate name. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all known elements barring carbon (which sublimes at normal pressure), melting at . It also has the highest boiling point, at . Its density is , comparable with that of uranium and gold, and much higher (about 1.7 times) than that of lead. Polycrystalline tungsten is an intrinsically brittle and hard material (under standard conditions, when uncombined), making it difficult to work. However, pure single-crystalline tungsten is more ductile and can be cut with a hard-steel hacksaw. Tungsten o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
