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Dopping Cement
Dopping cement, dopping wax, or faceting wax is a thermal adhesive used by gem cutting, gem cutters to secure ("dop") a gemstone to a wooden or metal holder ("dopstick", "Tounded stick") for Grinding (abrasive cutting), grinding and lapping. Setters cement is a similar material used to secure a gemstone while setting or polishing. Dopping cement is usually formulated so that it is hard at room temperature, but soft and moldable like putty at 45-65 °C, when it can still be shaped with the fingers. The cement is commercially sold as sticks or flat slabs. With metal dopsticks, a low-melting solder, tin-lead solder can be used for that purpose, instead of a dopping cement. Use In typical use, a small amount of cement is melted from the tip of a cement stick or from the edge of a cement slab by holding it over an alcohol lamp or similar source of heat. The tip of the dopstick is dipped into the molten cement, which is allowed to cool until it has the consistency of putty. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Adhesive
Thermal adhesive is a type of thermally conductive glue used for electronic components and heat sinks. It can be available as a paste (similar to thermal paste) or as a double-sided tape. It is commonly used to bond integrated circuits to heatsinks where there are no other mounting mechanisms available. The glue is typically a two-part epoxy resin (usually for paste products) or cyanoacrylate (for tapes). The thermally conductive material can vary including metals, metal oxides, silica or ceramic microspheres. The latter are found in products that have much higher dielectric strength, although this comes at the cost of lower thermal conductivity. End-user modding heatsinks may be supplied with thermal adhesive attached (usually a piece of tape). For products sold through electronic components distributors this is rarely the case; the adhesives are sold separately to professionals. See also * Computer cooling * Hot-melt adhesive * Phase-change material * Thermally conductive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chasers Pitch
Chaser's pitch is a thermal adhesive used by goldsmiths, silversmiths, coppersmiths, and other metal cold-working artisans to hold a metal plate for repoussage and "chasing" (embossing) while it is being hammered out. Generally, chaser's pitch must become soft or even liquid when heated at moderate temperatures, in order to fit the object and fill all its nooks and crannies. For many uses, it is desirable that the pitch is soft like glazing putty while it is still cool enough to be molded with the fingers. On the other hand, at room temperature it must be hard enough to hold the object. It must strongly adhere to the metal while it is cooling. There are many varieties of chaser's pitch available, that differ on the nature or the ingredients, physical properties (such as fusibility and hardness), or place of origin. Names include Swedish pitch, Red (or Brown) German pitch, green chaser's pitch, and black chaser's pitch. Handling Heating A heat gun is a preferred way to hea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Arts Terminology
The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photoreceptor cells, the optic nerve, the optic tract and the visual cortex) which gives organisms the sense of sight (the ability to perception, detect and process visible light) as well as enabling the formation of several non-image photo response functions. It detects and interprets information from the optical spectrum perceptible to that species to "build a representation" of the surrounding environment. The visual system carries out a number of complex tasks, including the reception of light and the formation of monocular neural representations, colour vision, the neural mechanisms underlying stereopsis and assessment of distances to and between objects, the identification of a particular object of interest, motion perception, the analysis and integration of visual information, pattern recognition, accurate motor coordination under visual guidance, and mor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Repoussé And Chasing
''Repoussé'' () or ''repoussage'' () is a metalworking technique in which a malleable metal is shaped by hammering from the reverse side to create a design in low relief. Chasing (French: '' ciselure'') or embossing is a similar technique in which the piece is hammered on the front side, sinking the metal. The two techniques are often used in conjunction. Many metals can be used for chasing and repoussé work, including gold, silver, copper, and alloys such as steel, bronze, and pewter. These techniques are very ancient and have been extensively used all over the world, as they require only the simplest tools and materials, and yet allow great diversity of expression. They are also relatively economical, since there is no loss or waste of metal, which mostly retains its original size and thickness. Toolmarks are often intentionally left visible in the result. A few among many famous examples of repoussé and chasing are the prehistoric Gundestrup cauldron, the mask on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turquoise
Turquoise is an opaque, blue-to-green mineral that is a hydrated phosphate of copper and aluminium, with the chemical formula . It is rare and valuable in finer grades and has been prized as a gemstone and ornamental stone for thousands of years owing to its unique hue. Like most other opaque gems, turquoise has been devalued by the introduction of treatments, imitations and synthetics into the market. The robin's egg blue or sky blue color of the Persian turquoise mined near the modern city of Nishapur in Iran has been used as a guiding reference for evaluating turquoise quality. Names The word ''turquoise'' dates to the 17th century and is derived from the French ''turquois'' meaning "Turkish" because the mineral was first brought to Europe through the Ottoman Empire.Turquoise . minerals.usgs.gov Howe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opal
Opal is a hydrated amorphous form of silica (SiO2·''n''H2O); its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Due to its amorphous property, it is classified as a mineraloid, unlike crystalline forms of silica, which are considered minerals. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl, and basalt. The name ''opal'' is believed to be derived from the Sanskrit word (), which means 'jewel', and later the Greek derivative (), which means 'to see a change in color'. There are two broad classes of opal: precious and common. Precious opal displays play-of-color ( iridescence); common opal does not. Play-of-color is defined as "a pseudo chromatic optical effect resulting in flashes of colored light from certain minerals, as they are turned in white light." The internal structure of precious opal causes it to di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beeswax
Beeswax (''cera alba'') is a natural wax produced by honey bees of the genus ''Apis''. The wax is formed into scales by eight wax-producing glands in the abdominal segments of worker bees, which discard it in or at the hive. The hive workers collect and use it to form cells for honey storage and larval and pupal protection within the beehive. Chemically, beeswax consists mainly of esters of fatty acids and various long-chain alcohols. Beeswax has been used since prehistory as the first plastic, as a lubricant and waterproofing agent, in lost wax casting of metals and glass, as a polish for wood and leather, for making candles, as an ingredient in cosmetics and as an artistic medium in encaustic painting. Beeswax is edible, having similarly negligible toxicity to plant waxes, and is approved for food use in most countries and in the European Union under the E number E901. Production The beeswax is formed by worker bees, which secrete it from eight wax-producing mirror glan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sealing Wax
Sealing wax is a wax material of a seal which, after melting, hardens quickly (to paper, parchment, ribbons and wire, and other material) forming a bond that is difficult to separate without noticeable tampering. Wax is used to verify something such as a document is unopened, to verify the sender's identity, for example with a signet ring, and as decoration. Sealing wax can also be used to take impressions of other seals. Wax was used to seal ''letters close'' and later, from about the 16th century, envelopes. Before sealing wax, the Romans used bitumen for this purpose. Composition Formulas vary, but there was a major shift after European trade with the Indies opened. In the Middle Ages sealing wax was typically made of beeswax and "Venice turpentine", a greenish-yellow resinous extract of the European Larch tree. The earliest such wax was uncoloured; later the wax was coloured red with vermilion. From the 16th century it was compounded of various proportions of shellac, turpe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shellac
Shellac () is a resin secreted by the female lac bug on trees in the forests of India and Thailand. It is processed and sold as dry flakes and dissolved in alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze and wood finish. Shellac functions as a tough natural primer, sanding sealant, tannin-blocker, odour-blocker, stain, and high-gloss varnish. Shellac was once used in electrical applications as it possesses good insulation qualities and it seals out moisture. Phonograph and 78 rpm gramophone records were made of it until they were replaced by vinyl long-playing records from 1948 onwards. From the time it replaced oil and wax finishes in the 19th century, shellac was one of the dominant wood finishes in the western world until it was largely replaced by nitrocellulose lacquer in the 1920s and 1930s. Etymology ''Shellac'' comes from ''shell'' and ''lac'', a calque of French , 'lac in thin pieces', later , 'gum lac'. Most European langua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gem Cutting
Lapidary (from the Latin ) is the practice of shaping stone, minerals, or gemstones into decorative items such as cabochons, engraved gem An engraved gem, frequently referred to as an intaglio, is a small and usually semi-precious gemstone that has been carved, in the Western tradition normally with images or inscriptions only on one face. The engraving of gemstones was a major lu ...s (including cameos), and faceted designs. A person who practices lapidary is known as a lapidarist. A lapidarist uses the lapidary techniques of cutting, grinding, and polishing. Hardstone carving requires specialized carving techniques. In modern contexts, a gemcutter is a person who specializes in cutting diamonds, but in older contexts the term refers to artists who produced hardstone carvings; engraved gems such as jade carvings, a branch of miniature sculpture or ornament in gemstone. By extension, the term ''lapidary'' has sometimes been applied to collectors of and dealers in gems, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alcohol Lamp
An alcohol burner or spirit lamp is a piece of laboratory equipment used to produce an open flame. It can be made from brass, glass, stainless steel or aluminium. Uses Alcohol burners are preferred for some uses over Bunsen burners for safety purposes, and in laboratories where natural gas is not available. Their flame is limited to approximately 5 centimeters (two inches) in height, with a comparatively lower temperature than the gas flame of the Bunsen burner. While they do not produce flames as hot as other types of burners, they are sufficiently hot for performing some chemistries, standard microbiology laboratory procedures, and can be used for flame sterilization of other laboratory equipment. Operation Typical fuel is denatured alcohol, methanol, or isopropanol. A cap is used as a snuffer for extinguishing the flame. See also * Bunsen burner * Heating mantle * Beverage-can stove * Portable stove A portable stove is a cooking stove specially designed to be porta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solder
Solder (; NA: ) is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable for use as solder should have a lower melting point than the pieces to be joined. The solder should also be resistant to oxidative and corrosive effects that would degrade the joint over time. Solder used in making electrical connections also needs to have favorable electrical characteristics. Soft solder typically has a melting point range of , and is commonly used in electronics, plumbing, and sheet metal work. Alloys that melt between are the most commonly used. Soldering performed using alloys with a melting point above is called "hard soldering", "silver soldering", or brazing. In specific proportions, some alloys are eutectic — that is, the alloy's melting point is the lowest possible for a mixture of those components, and co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
