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    Enamel

    A vitreous substance made of finely powdered glass colored with metallic oxide and suspended in an oily medium for ease of application with a brush.

    Glass-ceramics

    Materials produced from glass which have a polycrystalline structure.

    Containers, inspection

    Inspection of glass containers includes the following: gauging or measuring; inspection for specific faults; proof testing.

    Refractories

    Material capable of withstanding extremely high temperatures and thus used in furnaces for industries such as glass and steel where raw materials have to be heated to a molten form.

     

     

    K

    Kiln

    An oven used to process a substance by burning, drying, or heating. The result is a sheet of glass which is two or three times stronger than untempered glass and which, upon breakage, shatters into tiny pieces with blunt edges (the most common applications are for automotive glass). In glassmaking, furnaces are used for melting the batch, maintaining pots of glass in a molted state, and reheating partly formed objects at the glory hole.

     

     

    L

    Laminated glass

    Laminated (or compound) glass consists of two or more sheets of glass with one or more viscous plastic layers "sandwiched" between the glass panes.

     

     

    I

    I.

    Sometimes, several rings are required to fuse the different colors of an elaborately enameled object.

    Stemware

    The collective term given to drinking glasses whose body is connected to the base by a thinner column of glass. Such glass has a high refractive index and is particularly suited for decoration by cutting.

    Soda

    Sodium carbonate.

    Cutting

    The technique whereby glass is removed from the surface of an object by grinding it with a rotating wheel made of stone, wood, or metal, and an abrasive suspended in liquid. While still hot, the ends of the pod are cut off and the resulting cylinder cut lengthways and laid flat. Conductive coatings have been used to produce frost-free windscreens, and in a range of electro-optical applications.

    Annealing

    Under natural conditions, the surface of molten glass will cool more rapidly than the centre. The second medium normally used to establish the index is a vacuum. The medium burns away during firing in a low-temperature muffle kiln (about 965-1300°F or 500-700°C).

    The wires are encased in a protective sheath that can be introduced as a probe into the glass furnace or kiln.S.

     

     

    E

    Edging

    The shaping or finishing of the edges of a glass surface, usually by grinding with an abrasive wheel.

    Founding

    The initial phase of melting batch.

    Weathering

    Changes on the surface of glass caused by chemical reaction with the environment.

    Viscosity

    The quality or state of being viscous; the physical property of a liquid or semi-liquid that enables it to develop and maintain a certain amount of shearing stress dependent upon the velocity of flow and then to offer continued resistance to flow. These harden the surface of the glass, giving the inside more time to cool.

    Containers, defects

    Defects in automatically produced containers are categorized as very critical (Group 1), main faults (Group 2) and secondary (Group 3). It serves as a flux to reduce the fusion point of the silica when the batch is melted.

    Blowpipe

    An iron or steel tube, usually about five feet long, for blowing glass. The glass worker gathers directly from the pot. Following this initial blow, and then reheating, the parison is transferred to the finishing mould for the finishing blow. Pre-weighed and mixed batch materials are available in the form of pellets.

    Autoclave

    A strong vessel used for the lamination of glass under hugh pressure and controlled temperature conditions.

    Staple fibre

    Short lengths of glass fibre, usually U-shaped, which intertwine and are used, in particular, to create insulation materials. The task of the plunger is to help give the glass container its final shape inside the parison (or blank mould). (independent/individual section) container forming machines are made up of individual but identical sections placed side by side in line.

     

     

    N

    Narrow-neck ware

    Glass containers, such as bottles, whose opening is tapered and of smaller diameter than the body of the vessel. The first type uses the shaft to spin an abrasive wheel (often at high speed) in order to cut, score or polish glass; the second type uses the shaft to rotate a piece of glass so that it can be heated and manipulated. Day tanks are refilled with batch daily, with melting usually done at night and glass production the following day.

    Infrared lamp

    An incandescent lamp working at a low filament temperature and consequently emitting relatively high amounts of infrared radiation. Others have high physical strength and can be machined like metals. The distance between the rollers determines the thickness of the glass.

    Fibre glass

    Very fine strands of glass (normally with a high boric oxide and content) used in the form of glass wool for insulation, glass fibre for matting, etc.

     

     

    F

    Feeder

    A mechanism mounted on the casing of the forehearth which delivers the glass in gobs. This allows the external layer to crystallize into a wider lattice while the inside solidifies with greater compression than in the crystal lattice.

    Centrifuging process

    A relatively new method for the production of hollow ware such as borosilicate glass columns in chemical plants, funnels, television tubes and other non-rotationally symmetrical items by spinning.

     

     

    T

    Tank

    A large receptacle constructed in a furnace for melting the batch. It is water-soluble and not waterrepellent, facilitating the application of labels.

    Borosilicate glass

    Glass made from silica and boric oxide.

    Mixed feed

    The transfer of the various ingredients of the batch into the mixer by means of hoists, buckets and conveyor systems. Soda (or alternatively potash) is commonly used as the alkali ingredient of glass.

    Acid stamping

    The process of acid etching a trademark or signature into glass after it has been annealed, using a device that resembles a rubber stamp.) produced in a flat form, regardless of the method of production. Items to be polished are immersed in a mixture of demineralized water, sulphuric acid and hydrofluoric acid, and then rinsed.

    Embossing

    Carving or moulding in relief. batch ingredients, in pellet form (see also "pellet").

    Refining

    Refining ensures that a homogenous glass is produced during founding by eliminating bubbles (see also "bubbles"). The diameter and thickness of the glass tubing can be controlled by regulating the strength of the air flow through the mandrel and the speed of the drawing machine.

    Glass can be fed into the heated bushing either in its molten state from a forehearth (direct melt) or, alternatively, as marbles to be melted (re-melt process).

    Regenerative heating

    As in recuperative heating (see "recuperative heating"), waste heat from the furnace is used to pre-heat combustion air.

    Gob feeder

    A machine mounted at the end of the forehearth that dispenses gobs of molten glass of consistent size and weight for forming into glass containers.

    Acid etching

    This process for the decoration of glass involves the application of hydrofluoric acid to the glass surface.

    The chemical process, on the other hand, is based on the so-called ion-stuffing technique.

    Kiln forming

    The process of fusing or shaping glass (usually in or over a mould) by heating it in a kiln. Polyethylene coatings are transparent and give high lustre and lubricity to the glass surface. scratch resistance, solar control. When the glass has cooled sufficiently, rotation stops and the glass is removed. A takeout mechanism then lifts the container from the mould.

    Cold end

    The name given to the stage in glass production involving processing when the glass is cold. The resulting glass has a very low density but a high compressive strength and dimensional stability, making it particularly suitable for thermally and acoustically insulating construction materials. The process was developed by the UK firm Pilkington Brothers.

    Plunger

    A tool used in the production of glass containers during the first stage of shape forming in the IS machine. The solid joining of the glasses takes place in a pressurised vessel called an autoclave.

    Furnace

    An enclosed structure for the production and application of heat., dip moulds impart a pattern to the parison, which is then withdrawn, and blown and tooled to the desired shape and size; other moulds are used to give the object its final form, with or without decoration.1 mm).), domestic cooking ware (oven dishes, etc.

    Suck-blow process

    A process used for glass container manufacturing with forming machines. The inverted parison is transferred to an upright position in the blow mould where it is reheated before compressed air is introduced into the parison bubble.

    Larger bubbles which are not removed by fining are known as "blisters", smaller ones as "seeds" and longitudinally stretched bubbles as "air-lines".).

    Engraving methods include copper wheel engraving, diamond or tungsten point engraving, acid etching and sand blasting.

    Flat glass

    All types of glass (rolled, float, plate, etc.

    Fusing

    (1) The process of founding or melting the batch; (2) heating pieces of glass in a kiln or furnace until they bond (see casting and kiln forming); (3) heating enameled glasses until the enamel bonds with the surface of the object. As the ribbon of glass passes from the forming rollers, it is supported by an air cushion. At high speeds, the glass can assume almost cylindrical shapes. For many modern glasses, the materials must be heated to a temperature of about 2450°F 1400°C).

    The annealing process is designed to eliminate or limit such stresses by submitting the glass to strictly controlled cooling in a special oven known as a "lehr".

     

     

    W

    Waste gas analysis

    Gases emitted by the melt in the furnace can be analysed either in the furnace itself (in order to assess melting efficiency, for example) or as they are discharged from the furnace stack (above all, for pollution control purposes). In the former, the glass sheet is heated to a temperature just below its softening point and then immediately cooled by special jets of cold-air. Potash and soda are fluxes. The two main types are stearate- and polyethylene-based. Before being used in a batch, it is thoroughly washed, heated to remove carbonaceous matter, and screened to obtain uniformly small grains.

    Forehearth

    A refractory tank whose function is to receive glass from the furnace, reduce its temperature to the desired level and discharge it to the feeder mechanism at a uniform temperature.

    Hollow ware

    Made generally of soda-lime glass, but also of crystal, lead crystal and special glasses, hollow ware includes a wide variety of containers and receptacles: container glass (bottles, jars, medical and packaging glass), tableware (drinking glasses, bowls, etc.

    Chalcogenide glass

    Glass with electrical conductivity characteristics made with the addition of the chalcogen elements (sulphur, selenium and tellurium).

     

     

    M

    Melt

    The fluid glass produced by melting a batch of raw materials.

    Sand

    The most common form of silica used in making glass. This anhydrous, white powder is added to the glass batch, with sodium oxide becoming part of the glass and carbon dioxide being released. The glass is then cut into the size required

    2. The term "redox equilibria" is used to refer to the balance between reduction and oxidation in the glass furnace.

    Mirror

    Polished glass with a reflective coating of silver deposited on the back.

    Containers, enameling

    The application of enamel as a means of applying decoration and/or labeling to containers.

    Pressed glass

    Glassware formed by placing a blob of molten glass in a metal mould, then pressing it with a metal plunger or "follower" to form the inside shape.

    Armour plate glass

    Laminated glass, resistant to mechanical shock, composed of at least four panes of glass and usually at least 25 mm thick. Hydrofluoric acid vapours or baths of hydrofluoric acid salts may be used to give glass a matt, frosted appearance (similar to that obtained by surface sandblasting), as found in lighting glass. The process may be physical (thermal) or chemical.

    Cylinder glass

    A technique for producing sheet glass dating from the 11th century.

    AZS refractories

    Refractory blocks or tiles in varying proportions of alumina-zirconiasilica; initially used for areas where corrosion resistance was important but now used in most parts of the furnace. Although they are slightly water-repellent, most glues used ensure satisfactory adhesion. Devised by the American, Colburn, and further developed with the support of the US glassmaker Libbey-Owens, the process was patented in 1905, and was first used for commercial production in 1917.

    Tempering

    See toughening

    Thermal conductivity

    The passage of heat through a material. machine, mould. The most common form of silica used in glassmaking has always been sand.

    Pyrometer

    An instrument used to measure the temperature inside the furnace or kiln.

    Bottle-making machine

    See I. A separate mask is used for the application of each colour.

     

     

    V

    Vapour deposition of thin fims

    The term covers a wide range of techniques for applying a thin film on the surface of the glass to change its technical or aesthetic properties e.

    Limestone

    A sedimentary rock composed mainly of calcium carbonate which is added to the batch to provide calcium oxide. machines

    Boudin process

    A glass rolling process in which glass flow is controlled by the speed of the machine and fed directly onto the rollers over a refractory sill.

    Mould, optic

    An open mould with a patterned interior in which a parison of glass is inserted, then inflated to decorate the surface. One of the two principal types of optical glass used in the production of compound lenses.

     

     

    D

    Dalle glass

    Coloured glass produced in pot furnaces and cast in moulds to form plates in thicknesses of approximately 25 cms. The glass can be stabilised against devitrification and weathering by adding small amounts of substances such as aluminium oxide

    Batch

    A term used to refer to the raw materials required to produce the desired type of glass once they have been weighed and mixed, and are ready for melting.

     

     

    B

    Banding

    The application of decorative bands of enamel or precious-metal compounds, normally by machine, to containers such as tumblers, cups, cosmetics bottles, etc.

     

     

    O

    Owens-Illinois coating techniques

    Techniques developed by the Owens Illinois company for the surface treatment of glass containers. See also Enamel

    Containers, forming

    The process of turning a gob of molten glass into a hollow container was first mechanized towards the end of the 19th Century.

    Firing

    The process of bringing a glass furnace up to its operational temperature and then maintaining the temperature.S.

    Thermocouple

    A pair of different metals in contact at a point, generating a thermo-electric voltage which can serve as a measure of temperature. Weathering usually involves the leaching of alkali from the glass by water, leaving behind siliceous weathering products that are often laminar. Hence, if glass containing sodium is cooled slowly in a salt bath of molten potassium, the sodium ions will migrate from the glass to the salt, while the potassium ions will move to the surface of the glass where, due to their wider radium, they create a denser and therefore stronger surface layer (of no less than 0.S.

    By blowing a hollow glass sphere and swinging it vertically, gravity pulls the glass into a cylindrical "pod" measuring up to 3 metres long, with a width of up to 45 cm. When the glass has cooled sufficiently, rotation stops and the glass is removed. The drawing speed with the Libbey-Owens process is twice that of the Fourcault process. B.

    Furnace gas testing may be performed with Orsat equipment (gases are absorbed selectively as they pass through a series of specific solvents) or by means of instrumental analysis.

    Dolomite

    A raw material compound (CaCO3 + MgCO3) of calcium carbonate and magnesium oxide, which helps lower the melting temperature in the production of flat glass. Glass is sucked from the tank of molten glass into the parison mould and then cut by shears.

    Mould

    A form, normally made of wood or metal, used for shaping and/or decorating molten glass.

    Toughening

    Special process of solidification of a glass sheet in order to make it particularly resistant to breakages. Shears for the cutting of the glass flow into gobs are operated through the same cam system as that of the plunger to ensure constant gob size.

    Muffle kiln

    A low-temperature kiln for refiring glass to fuse enamel, fix gilding, and produce luster.

    Plate glass

    Flat glass made by the casting or rolling of molten glass which is then mechanically ground and polished to produce a smooth and transparent sheet.

    Soda-lime glass

    The most common type of industrially produced glass. Any of a group of aluminium silicates of potassium, sodium, or calcium. (see "regenerative heating"). The rate of flow of the molten glass is regulated by the use of different sized orifices in the feeder spout and by a plunger which pushes the glass through the orifice.

    Lathes

    Two distinct types of lathe exist, although both basically consist of a horizontal shaft rotated by a motor. machine more flexible than continuous- or intermittent-motion rotary machines. In the autoclave, under simultaneous heating of the already processed layers of glass and special plastic, lamination occurs.

    Crown glass

    1.

    In the Danner process, the glass flow falls onto a rotating, slightly downward pointing mandrel. It is collected from the seashore or, preferably, from deposits that have fewer impurities.

    Heating up

    Raising the temperature within the furnace to the required operating temperature under strictly controlled conditions, ensuring the homogenous expansion of refractory materials.

    Wired glass

    Flat rolled glass reinforced with wire mesh and used especially for glass doors and roofing to prevent objects from smashing through the glass and also to hold pieces of broken glass together.

    Stearate treatment using polyoxyethylene monostearate gives good lubricity and reduced friction.

    Spinning, hollow ware

    A relatively new method for the centrifugal production of hollow ware such as borosilicate glass columns in chemical plants, funnels, television tubes and other non-rotationally symmetrical items. Group 3 defects represent a lowering of the quality of the container but do not affect the functionality of the container.

    In contemporary glassworking kilns are used to fuse enamel and for kilnforming processes such as slumping. Enamel patterning or labeling is typically applied by automated silk screening; all-over color can be applied by spraying.

    Mould, dip

    A cylindrical, one-piece mould that is open at the top so that the gather can be dipped into it and then inflated.

     

     

    H

    Heat resistant glass

    Glass which has a low coefficient of expansion and which is therefore less liable to thermal shock.

    Neck-ring

    In the production of glass containers, the tool coupled with the blank mould (parison) which gives the shape to the neck of the container.

    Preston test

    The means of verifying the bursting strength of a glass container during automatic inspection.) and fluorescent lighting. Insulation materials are defined as having 'low' thermal conductivity whereas metallic materials generally have 'high' thermal conductivity.

    Furnace, pot

    A pot furnace consists of a melting chamber lined with refractory brick, a vaulted roof or "crown" of silica brick, and external walls made of insulating brick. The gobs are fed into the forming machine to be moulded into bottles and other glass objects. However, since the stearate is destroyed by firing or any subsequent processing, the treatment needs to be repeated after the firing of applied colour labels.

    Alumina-silicate glass (1)

    Alumina (aluminium oxide Al2O3) is added to the glass batch in the form of commonly found feldspars containing alkalis in order to help improve chemical resistance and mechanical strength, and to increase viscosity at lower temperatures. The fusion temperature for soda-lime glasses is generally between 760°C and 820°C.

    Blowpipes have a mouthpiece at one end and are usually fitted at the other end with a metal ring that helps to retain a gather. Stearic acid is of vegetable origin, making this type of coating also suitable for kosher foods. Below the upper chamber in which there may be as many as twelve melting pots, there is a lower section for the pre-heating of the fuel gas. Venturi, who died in 1822.

    Commonly used on mirror glass. One way of producing a conductive coating is by depositing tin salts onto the glass.

    Glory hole

    A hole in the side of a glass furnace, used to reheat glass that is being fashioned or decorated. Some moulds (e. By holding the glass together, it can also protect against break-in and the spreading of fire.

     

     

    C

    Cast glass

    Glass produced by 'casting', in other words by pouring molten glass into a mould or by heating glass already contained in the mould until the glass melts and assumes the shape of the mould.

    Tube-drawing process

    See danner process

    Tubing

    Hollow rods of glass used especially in the production of laboratory/medical equipment (ampoules, vials, etc. When applied, the acid will corrode the glass but not attack the wax-covered areas.

    Bubbles

    Gaseous inclusions in the glass melt which are removed by refining (see "fining").). During blowing, a vacuum is applied through the mould to suck any trapped air or other gases from the bottom of the mould.

    Infrared bulbs are usually made of borosilicate glass with molybdenum or tungsten wires.), high-power lamps and other technical glass ware.

    Alkali-borosilicate glass

    A special glass used for glass-to-metal seals, particularly suitable when electrical qualities are not important.

    Group 1 defects make the container dangerous and unusable; Group 2 defects make the container unusable; containers with group 1 or group 2 defects must be discarded.

    Screen printing

    A process for the decoration of glass whereby coloured ink is forced by a flexible "squeegee" through a fine-mesh screen, or "mask", (traditionally made of silk, now also made of nylon, polyester and stainless steel) onto the glass surface.

     

     

    P

    Pellet

    A small block of compressed matter. The forehearth usually consists of two sections: a cooling section with burners and cooling ducts which allow the cooling process to be regulated, and a conditioning (equalising) section generally equipped only with burners which ensure uniform temperature distribution through the glass flow as it enters the feeder.

    Float process

    A method for the production of high-quality sheet glass whereby a ribbon of molten glass is fed across a bath of heated liquid, usually molten tin, in a carefully controlled atmosphere.

    Rolled glass

    Rolled (or cast) glass is a translucent glass with 50-80% light transmission, depending on its thickness and type of surface.). Suction cups are used in both the manual and automatic handling and conveyance of glass.

    Gob

    A drop of still molten glass formed by the cutting of the stream of glass as it flows from the forehearth through a feeder into a spout/orifice of variable diameter; the greater the diameter, the larger the gob. Each section comprises an arrangement of mechanisms with gears enabling the sections to be started or stopped independently of the others, making the I.

    Day tank

    A glass-containing vessel made from refractory blocks mainly used for the melting of batch for coloured glass, crystal glass and soft special glasses.

    Used in the production of pressed glass hollow ware. Air traps in stems are frequently tear-shaped or spirally twisted.

    See also gob feeder, press-and-blow, blow-and-blow, I. Molten glass is fed into a steel mould which rotates at the required speed.

    Wired glass is produced by continuously feeding wire mesh from a roller into the molten glass ribbon just before it undergoes cooling. In glass, the shock may derive from the external surface of glass expanding or contracting more rapidly than the interior surface as a result of heating or cooling.

    Glass designs can be produced by coating the glass with wax and then inscribing the desired pattern through the wax layer. Dalle glass ("dalle" is French for "tile") is used in church and decorative glazing, as well as for furnishings such as door handles. Fining agents induce the formation of large bubbles which collect smaller bubbles as they rise to the surface.

    Hot spot

    Inside the furnace, the hot spot is that area on the surface of the melt which has reached the maximum temperature (at which batch reactions have been completed and dissolved gases have been reduced to acceptable levels). Also known as the "spring" or "source".

    Air trap, air lock

    An air-filled void, which may be of almost any shape.

    The glass ribbon is drawn vertically from the tank for about 70 cm by a metal "bait" before being bent over a roller into the horizontal plane ready for cutting and annealing. The gobs are then fed down chutes to the forming machine.

    Soda ash

    Sodium carbonate (Na2CO3), or 'soda ash', is the main source of sodium oxide (Na2O), or 'soda'.

    Phial

    See "vial".

    Bevelling

    The production, by abrasion, of a sloping edge on the glass sheet. Low-E glass thus allows light to enter while also providing thermal insulation.

    Pelletising

    The preparation of materials, e.

    Inleakage

    The unwanted entry of air into a furnace through expansion-created gaps in the furnace superstructure or through other areas such as burner ports, regenerators and exhaust flues.

    Bonding agents can also be added so that refractories can be shaped.) and lighting glass (lamps, bulbs, etc.

    Grinding processes include milling, sawing, edging and drilling. A plunger inside the mould produces a hollow space in the glass which is then enlarged by blowing.

    Coating

    A thin layer which covers the surface of an object. Air is blown down a shaft through the middle of the mandrel, thus creating a hollow space in the glass as it is drawn off the end of the mandrel by a tractor mechanism. Used in the batch as a means of adding alumina to the molten glass.

    Lead crystal

    The type of glass produced when lime in the batch is replaced by lead oxide. At high speeds, the glass can assume almost cylindrical shapes. In industrial production, it usually has a moving belt to carry the glass through at controlled speeds, and is divided into different areas each with its own heat source, making it possible to carefully regulate the temperature gradient to which the glass is submitted. The temperature is increased until the glass sheet sinks into shape in the mould.

     

     

    S

    Safety glass

    Glass which does not disintegrate into sharp and potentially dangerous splinters when it is broken.

    Engraving

    The production of a design in glass by cutting into the glass surface. The tube-shaped glass is pulled from the end of the shaft by a tractor machine and turned through 90° into a horizontal position ready for cutting. anti-reflective coatings applied to auto mirrors to aid vision, coatings with photocatalytic and hydrophilic properties to make self-cleaning windows.

    Alumina-silicate glass (2)

    A special glass used for glass-to-metal seals, particularly suitable when operating temperatures of electrical components are high (up to 750°C).

    Philips process

    A variation of the Schuller up-draw process (patented in Germany in 1931) for the mechanical manufacture of glass tubing and rod.

    Bending

    A process used widely in the production of bowls, plates, ashtrays, etc.

    Fining

    The process by which gaseous inclusions are removed from the glass melt after all batch materials have been added.

    Foam glass

    Glass with a high bubble content, produced by adding additional gases or gas forming substances to the glass melt. Cold end processes include grinding, engraving, cutting, etc. Inside the lehr, the glass is allowed to cool to a temperature known as the "annealing point". Used for producing larger quantities of glass than is possible with pot furnaces (see "pot"). Bubbles in glass are generally considered as defects but may also be intentionally created and used as a form of decoration (see "air twist")

    Bulletproof glass

    Armour plate glass which is more than 60 mm thick and which resists penetration by bullets. The glory hole is also used to fire-polish cast glass to remove imperfections remaining from the mould. The equipment in use today is descended from these innovations.), medico-technical glassware (laboratory equipment, tubing, etc.

    Burners

    Used to heat glass in furnaces of all sizes, burners mix air (or oxygen) and gas (natural gas or liquid petroleum gases) for efficient combustion.

    Most offer advantages of low thermal expansion, making them suitable for uses such as cookware. Inleakage can result in decreased efficiency and increased fuel costs., whereby the shaped glass article (which may be pre-printed) still in sheet form is placed on a stainless steel, sheet steel or cast iron mould coated with talc or powdered chalk. Any such difference may lead to cracking or shattering.

    Flux

    A substance that lowers the melting temperature of another substance. The Crown glass, which is an alkali-lime silicate optical glass, has a low index of refraction and low dispersion (its Abbe v-value is larger than 50 or 55, depending on its index).

    Furnace, tank

    See Tank. This is produced by reheating and spinning out a bowl-shaped piece of glass (bullion) that causes the glass to extend into a flat disk by centrifugal force. Fining agents are introduced to encourage the formation of larger bubbles which rise more rapidly to the surface of the melt, attracting smaller bubbles on their way.

    Fusing glass-to-glass

    Glasses of different compositions can be fused together for decorative purposes and also in the sealing of electrical, medical and industrial components. Once the first chamber has been heated up, exhaust gases are diverted to heat the second chamber, while cold combustion gas is introduced into the first chamber to be pre-heated by the hot refractory blocks.

    During the shaping process in the IS machine, the neck ring transports the glass container into the blow mould (or finishing mould). The molten glass is covered with the batch material as it flows through the compartment.

    Frosting

    The process of giving a glass surface a matt finish, thus reducing transparency. This results in internal stresses which may cause the glass sheet or object to crack, shatter or even explode some time later. Refining is achieved through the action of certain chemicals (refining agents) added to the batch recipe and also by keeping the glass above the liquidus temperature so that the bubbles rise to the surface.

    Inspection for specific faults: cracks (also known as checks); stones; foreign material (tramps); spikes; birdswings; thin spots.S. The methods employed to deposit the film include spraying onto hot glass, condensation in a vacuum and evaporation of the film material by heating.

    Pot furnaces are used today in the manufacture of mouth-blown glass objects and special glasses.

    Low emissivity on Low-E glass

    Commonly known as "low-E" glass and often used in double and triple glazing units, this window glass has a special thin-film metallic or oxide coating which allows the passage of short-wave solar energy into a building but prevents long-wave energy produced by heating systems and lighting from escaping outside., and also for the reinforcement of plastics. Paramagnetic detection may be used for oxygen analysis, and infrared absorption for carbon dioxide analysis. When the glass reaches this point, the lehr temperature is stabilized for a specific length of time (depending on the glass type, its thickness, its coefficient of expansion and the amount of residual stress required) to allow stresses present in the glass to relax.

    Sheet glass processes

    See the definitions for the following processes, listed in order from oldest to most recent: "crown glass" (definition 1), "cylinder glass", "drawn glass", "Fourcault process", "Libbey-Owens process", "Pittsburgh process", "float process". The elongated gob of molten glass formed by the gob feeder falls into the inverted parison (blank) mould.

    Silica

    Silicon dioxide, a mixture that is the main ingredient of glass.

    The principal production process involves blowing jets of steam or air onto molten glass as it emerges from a tank furnace through very small diameter nozzles. Glass from the furnace forehearth flows down through an orifice (ring) within which is a rotating conical-ended shaft (or mandrel) over and around which the glass flows. The resultant piece, termed "mould-pressed," has an interior form independent of the exterior, in contrast to mouldblown glass, whose interior corresponds to the outer form.

    Blow-and-blow process

    A production process used for glass container manufacturing with forming machines.S.

    Conductive coating

    A glass coating which is electrically conductive.

    When laminated safety glass breaks, the pieces remain attached to the internal plastic layer and the glass remains transparent. The float process is now the standard method of producing sheet glass world-wide. Safety glass may be produced by laminating (see "laminated glass") or by tempering (see "tempering"). The process can be adapted in order to introduce wire mesh into the glass ribbon.

    To produce rolled glass, molten glass pours from the melting tank over a refractory barrier (the "weir") and onto the machine slab where it flows under a refractory gate (the "tweel"), which regulates the volume of glass, and then between two water-cooled rollers.

    Vial

    A small cylindrical glass vessel especially for holding liquid medicines. Fully automatic machines were developed during the first quarter of the 20th Century, principally in the USA, using the blow-and-blow process for narrow-neck ware and the press-and-blow process for wide-neck ware. Coatings may be applied to glass in order to alter the appearance or performance of the product in question e.g.g.

    Refractive index

    A standard of measurement used particularly to establish the qualities of optical glass. The landmarks in the development of automatic forming of containers were the gob feeder in 1923, which automated delivery of consistently sized gobs of glass, and the individual section bottle making machine in 1925.

    Pot

    A fire clay container placed in the furnace in which the batch of glass ingredients is fused, and kept molten. For most present-day glassmaking, sand must have a low iron content. The omposition of lead crystal is 54-65% silicon dioxide (SiO2), 18-38% lead oxide (PbO), 13-15% soda (Na2O) or potash (K2O), and other oxides. Tanks replaced pots in larger glass factories in the 19th centry.

    Considerable automation of the process has been developed, thus allowing extremely high printing speeds for even complex designs. By pressing the cup onto a glass surface and removing air from inside the cup, the vacuum thus created holds the cup and glass together.g. Such glass is highly resistant to chemical corrosion and temperature change (thermal shock) and is particularly suitable for laboratory ware (test tubes, etc. This phase is followed by a period of cooling with a pre-defined temperature gradient. Borosilicate glass is the most common type of heat resistant glass.

    Push-up

    The base of a glass bottle (particularly of a wine bottle) which is pushed upwards inside the bottle during the forming process.

    Waste-heat recovery

    An economy measure whereby the heat of exhaust gases is used in a cyclic process to pre-heat combustion air and/or fuel-gas. Frosting may be by means of acid treatment (pouring hydrofluoric acid onto the glass), sandblasting, special glue application and subsequent removal, or mechanical etching with a grinding wheel.

    Electrode

    A metal conductor through which electricity enters or leaves an electrolyte, gas, vacuum, etc.

    Doghouse

    The name used to describe the batch feeding compartment within the furnace.

    In smaller workshops, the lehr may be a simple kiln with a shelf for the glassware rather than a moving belt, and with electronic controls to programme the temperature cycle required.

    Drawn glass

    A process for making sheet glass by drawing the molten glass as a sheet directly from the furnace. Particular attention must be paid to the thermal expansion coefficients of different glass types. There may be a single short immersion in a stronger solution or, alternatively, a series of immersions in a weaker solution.

    Grinding

    The removal of glass with abrasives or abrasive (grinding) wheels in order to shape, polish or otherwise finish both flat and hollow glass. See Kiln.

    Lehr

    A special type of oven or kiln used specifically for annealing glass (see "annealing"). It is used where transparency of the glass sheet is not important or not desired.

    Polyethylene coatings are deposited from a water emulsion but are not water-soluble and can thus withstand washing and pasteurising. The process was developed by an American engineer, Edward Danner, in 1912. The material, molten in the case of glass, is forced through a die and cut to the required length. Window glass blown into a crown or hollow globe that is flattened and cut before use. A typical soda-lime glass is composed of silica (71-75%), soda (12-16%) and lime (10-15%), plus small amounts of other materials to provide particular properties such as colour.

    Suction cup

    A semi-spherical cup of flexible material such as rubber. Molten glass is fed into a steel mould which rotates at the required speed.

    Vello process

    A drawing process used for the production of glass tubing.

     

    .

    Thermal shock testing

    Assessing the effects on a material of rapid temperature change.

    Danner process

    A widely used method for the production of glass tubing.), construction hollow ware (glass building blocks, etc. Continuous reversal of this process provides a permanent flow of pre-heated gas for combustion. The forming or application of figures or patterns to an object so that they stand out from the surface.

    Bushings

    Platinum alloy electrically-heated boxes with numerous nozzles in their bases used as furnaces for the forming of continuous glass fibre.

    Gauging or measuring checks: height, diameter and verticality; choke (inner and outer dimension of the neck); dips and saddles in the finish area (mouth/seal of the container); wall thickness. machine

    I. It is blown down into the mould (settle blow) before being blown from below

    (counter blow) back up into the now closed mould. The manufacturing process requires that the raw materials be heated to a temperature sufficient to produce a completely used melt, which, when cooled rapidly, becomes rigid without crystallizing. It is also used when glass has to be bonded to metal and low expansion is a key characteristic.

    Redox

    The abbreviated form of "reduction-oxidation".

    Acid polishing

    A process used in the production of cut crystal to remove the opacity of etched surfaces where decoration has been applied. The index is the ratio of the sine of the angle of incidence of a ray of light to the sine of the angle of refraction (the change in direction when a ray of light passes from one medium to another) by the glass.g.

     

     

    R

    Raw materials, for basic refractories

    Basic refractories are made up of various mixes of periclase (magnesium oxide), chromite (chrome ore) and forsterite (olivine). The process of pressing glass was first mechanized in the United States between 1820 and 1830. The thickness of the glass is determined by the drawing rate.

    Mould, block

    A particular type of mould produced in a single piece of cast iron, hollowed into a specific shape using a cold-deformation process. Mass spectrometry or gas chromatography are also used to analyse gas mixtures.

    Feldspar

    Also known as "felspar". From the spout of the forehearth the molten glass flow out through an orifice, the size of which influences the flow rate of the glass. A cylindrical plunger moves up and down to accelerate or slow the flow of molten glass through the orifice.

    Extrusion

    A process for the production of continuous strips or rods of material such as glass and also the butyl used in the sealing of insulating glass units.

    Flue

    A duct or channel for conveying heat or exhaust gases.

    Domestic ware

    The collective term for glass containers used in the home (oven dishes, bowls, jars, etc. For example, a flux is added to the batch in order to facilitate the fusing of the silica. This is followed by a maturing period, during which the molten glass cools to a working temperature of about 2000°F (1100°C).

    Glass sheets which have been chemically tempered are five to eight times stronger than those which have not undergone any tempering process.

    Proof testing: simulated impact; vertical load.

    Venturi tubes

    Short pieces of narrow tube between wider sections of tube, used for exerting suction or measuring flow rates and invented by the Italian physicist G. (See also "Pilkington double-pass wired glass process" and "wired glass). Different chemical elements possess different ionic radii and therefore different densities. Fluxes are also added to enamels in order to lower their fusion point to below that of the glass body to which they are to be applied.

    Libbey-Owens process

    A method for the production of sheet glass by means of a continuous drawing process.

    Regenerative heating is a cyclic process whereby exhaust gases pass over and thus heat up refractory blocks in one of two pre-heating chambers.

    Barium crown glass

    Barium crown glasses contain larger proportions of boron oxide and barium oxide with a relatively low SiO2 content.

    Redox equilibra

    Used to refer to the balance between reduction and oxidation in the glass furnace.

     

     

    G

    Glass

    A homogeneous material with a random, liquidlike (non-crystalline) molecular structure. The type of glass to be melted can be changed at short notice. Linked to the motion of the plunger is a shear that cuts the molten glass into gobs at the correct point in relation to the plunger action
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