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    It is collected from the seashore or, preferably, from deposits that have fewer impurities., dip moulds impart a pattern to the parison, which is then withdrawn, and blown and tooled to the desired shape and size; other moulds are used to give the object its final form, with or without decoration.

    Stemware

    The collective term given to drinking glasses whose body is connected to the base by a thinner column of glass. See Kiln.

    Bottle-making machine

    See I.

    Lehr

    A special type of oven or kiln used specifically for annealing glass (see "annealing"). For many modern glasses, the materials must be heated to a temperature of about 2450°F 1400°C).

    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.).

    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. Cold end processes include grinding, engraving, cutting, etc. Dalle glass ("dalle" is French for "tile") is used in church and decorative glazing, as well as for furnishings such as door handles. Others have high physical strength and can be machined like metals.). The methods employed to deposit the film include spraying onto hot glass, condensation in a vacuum and evaporation of the film material by heating.

    Regenerative heating

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

    Bushings

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

     

     

    I

    I.

    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.

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

    Mirror

    Polished glass with a reflective coating of silver deposited on the back. Mass spectrometry or gas chromatography are also used to analyse gas mixtures.

    Containers, inspection

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

    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.

    Infrared bulbs are usually made of borosilicate glass with molybdenum or tungsten wires. A separate mask is used for the application of each colour.

    Alkali-borosilicate glass

    A special glass used for glass-to-metal seals, particularly suitable when electrical qualities are not important. It is blown down into the mould (settle blow) before being blown from below

    (counter blow) back up into the now closed mould.

    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. 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. 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. Also known as the "spring" or "source".

    Thermal shock testing

    Assessing the effects on a material of rapid temperature change.

    Autoclave

    A strong vessel used for the lamination of glass under hugh pressure and controlled temperature conditions. 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. The fusion temperature for soda-lime glasses is generally between 760°C and 820°C.

    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.

    Tube-drawing process

    See danner process

    Tubing

    Hollow rods of glass used especially in the production of laboratory/medical equipment (ampoules, vials, etc.

    Barium crown glass

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

    Kiln forming

    The process of fusing or shaping glass (usually in or over a mould) by heating it in a kiln.

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

    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.

    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. Paramagnetic detection may be used for oxygen analysis, and infrared absorption for carbon dioxide analysis.

     

     

    G

    Glass

    A homogeneous material with a random, liquidlike (non-crystalline) molecular structure. Air traps in stems are frequently tear-shaped or spirally twisted. A takeout mechanism then lifts the container from the mould., and also for the reinforcement of plastics.

    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. Continuous reversal of this process provides a permanent flow of pre-heated gas for combustion.

    When laminated safety glass breaks, the pieces remain attached to the internal plastic layer and the glass remains transparent.

     

     

    R

    Raw materials, for basic refractories

    Basic refractories are made up of various mixes of periclase (magnesium oxide), chromite (chrome ore) and forsterite (olivine).

    See also gob feeder, press-and-blow, blow-and-blow, I. 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.

    Bevelling

    The production, by abrasion, of a sloping edge on the glass sheet.

    The wires are encased in a protective sheath that can be introduced as a probe into the glass furnace or kiln. Coatings may be applied to glass in order to alter the appearance or performance of the product in question e.

    Philips process

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

    In the Danner process, the glass flow falls onto a rotating, slightly downward pointing mandrel.

    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.

    Feldspar

    Also known as "felspar". 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. Such glass is highly resistant to chemical corrosion and temperature change (thermal shock) and is particularly suitable for laboratory ware (test tubes, etc. Particular attention must be paid to the thermal expansion coefficients of different glass types. 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. Used in the batch as a means of adding alumina to the molten glass.

    Conductive coating

    A glass coating which is electrically conductive.), domestic cooking ware (oven dishes, etc. The gobs are then fed down chutes to the forming machine. Potash and soda are fluxes. The thickness of the glass is determined by the drawing rate.

    Commonly used on mirror glass.

    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.

    Glass-ceramics

    Materials produced from glass which have a polycrystalline structure.

     

     

    F

    Feeder

    A mechanism mounted on the casing of the forehearth which delivers the glass in gobs.

    Proof testing: simulated impact; vertical load.

    Founding

    The initial phase of melting batch. Venturi, who died in 1822. 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.g.

    Flat glass

    All types of glass (rolled, float, plate, etc. scratch resistance, solar control.) produced in a flat form, regardless of the method of production.

     

     

    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. (See also "Pilkington double-pass wired glass process" and "wired 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.

    Muffle kiln

    A low-temperature kiln for refiring glass to fuse enamel, fix gilding, and produce luster. Day tanks are refilled with batch daily, with melting usually done at night and glass production the following day. Weathering usually involves the leaching of alkali from the glass by water, leaving behind siliceous weathering products that are often laminar.

    Wired glass is produced by continuously feeding wire mesh from a roller into the molten glass ribbon just before it undergoes cooling. B.

     

     

    D

    Dalle glass

    Coloured glass produced in pot furnaces and cast in moulds to form plates in thicknesses of approximately 25 cms.

    Danner process

    A widely used method for the production of glass tubing. A cylindrical plunger moves up and down to accelerate or slow the flow of molten glass through the orifice. Inside the lehr, the glass is allowed to cool to a temperature known as the "annealing point". The material, molten in the case of glass, is forced through a die and cut to the required length.

     

     

    E

    Edging

    The shaping or finishing of the edges of a glass surface, usually by grinding with an abrasive wheel. The distance between the rollers determines the thickness of the glass. When the glass has cooled sufficiently, rotation stops and the glass is removed.

    Frosting

    The process of giving a glass surface a matt finish, thus reducing transparency. By holding the glass together, it can also protect against break-in and the spreading of fire.

     

    .

    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. machine, mould. (see "regenerative heating").

    Toughening

    Special process of solidification of a glass sheet in order to make it particularly resistant to breakages.

    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".

    Bonding agents can also be added so that refractories can be shaped.

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

    Drawn glass

    A process for making sheet glass by drawing the molten glass as a sheet directly from the furnace.S.

    Annealing

    Under natural conditions, the surface of molten glass will cool more rapidly than the centre. Insulation materials are defined as having 'low' thermal conductivity whereas metallic materials generally have 'high' thermal conductivity. At high speeds, the glass can assume almost cylindrical shapes. Different chemical elements possess different ionic radii and therefore different densities. Enamel patterning or labeling is typically applied by automated silk screening; all-over color can be applied by spraying. The process was developed by the UK firm Pilkington Brothers. 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.

    Foam glass

    Glass with a high bubble content, produced by adding additional gases or gas forming substances to the glass melt.

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

    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). 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 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".), high-power lamps and other technical glass ware. The temperature is increased until the glass sheet sinks into shape in the mould.

    Refractive index

    A standard of measurement used particularly to establish the qualities of optical glass. Suction cups are used in both the manual and automatic handling and conveyance of glass.

    Heating up

    Raising the temperature within the furnace to the required operating temperature under strictly controlled conditions, ensuring the homogenous expansion of refractory materials. Group 3 defects represent a lowering of the quality of the container but do not affect the functionality of the container.

    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.

    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. The elongated gob of molten glass formed by the gob feeder falls into the inverted parison (blank) mould.

    Grinding processes include milling, sawing, edging and drilling. 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. Pre-weighed and mixed batch materials are available in the form of pellets.

    Sometimes, several rings are required to fuse the different colors of an elaborately enameled object. The equipment in use today is descended from these innovations.

    Mould

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

    Limestone

    A sedimentary rock composed mainly of calcium carbonate which is added to the batch to provide calcium oxide. In the autoclave, under simultaneous heating of the already processed layers of glass and special plastic, lamination occurs.

     

     

    P

    Pellet

    A small block of compressed matter.

    Furnace

    An enclosed structure for the production and application of heat. The task of the plunger is to help give the glass container its final shape inside the parison (or blank mould).

     

     

    H

    Heat resistant glass

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

    In contemporary glassworking kilns are used to fuse enamel and for kilnforming processes such as slumping.

    Soda-lime glass

    The most common type of industrially produced glass. The molten glass is covered with the batch material as it flows through the compartment.

    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.

    Thermocouple

    A pair of different metals in contact at a point, generating a thermo-electric voltage which can serve as a measure of temperature. The type of glass to be melted can be changed at short notice. The process can be adapted in order to introduce wire mesh into the glass ribbon. Each section comprises an arrangement of mechanisms with gears enabling the sections to be started or stopped independently of the others, making the I. The most common form of silica used in glassmaking has always been sand.S. Tanks replaced pots in larger glass factories in the 19th centry. anti-reflective coatings applied to auto mirrors to aid vision, coatings with photocatalytic and hydrophilic properties to make self-cleaning windows.

    Used in the production of pressed glass hollow ware. 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.

    Lead crystal

    The type of glass produced when lime in the batch is replaced by lead oxide.

    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.

    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. A plunger inside the mould produces a hollow space in the glass which is then enlarged by blowing.

    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. 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.

    Electrode

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

    Bubbles

    Gaseous inclusions in the glass melt which are removed by refining (see "fining").

    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.

     

     

    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.

    Phial

    See "vial".

    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.

    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.

    Pot

    A fire clay container placed in the furnace in which the batch of glass ingredients is fused, and kept molten.

    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.

    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).S.

     

     

    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. Soda (or alternatively potash) is commonly used as the alkali ingredient of glass.

    Weathering

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

    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.

    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.

    Flux

    A substance that lowers the melting temperature of another substance. Following this initial blow, and then reheating, the parison is transferred to the finishing mould for the finishing blow.

    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. machine

    I.

    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.

    Glass designs can be produced by coating the glass with wax and then inscribing the desired pattern through the wax layer.

    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.

    Redox equilibra

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

    Doghouse

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

    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.

     

     

    M

    Melt

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

    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.

    Domestic ware

    The collective term for glass containers used in the home (oven dishes, bowls, jars, etc. Safety glass may be produced by laminating (see "laminated glass") or by tempering (see "tempering"). Any of a group of aluminium silicates of potassium, sodium, or calcium.

    Flue

    A duct or channel for conveying heat or exhaust gases.

    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. The glory hole is also used to fire-polish cast glass to remove imperfections remaining from the mould.

     

     

    O

    Owens-Illinois coating techniques

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

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

    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 chemical process, on the other hand, is based on the so-called ion-stuffing technique. As the ribbon of glass passes from the forming rollers, it is supported by an air cushion. When the glass has cooled sufficiently, rotation stops and the glass is removed. Although they are slightly water-repellent, most glues used ensure satisfactory adhesion. It is water-soluble and not waterrepellent, facilitating the application of labels. This anhydrous, white powder is added to the glass batch, with sodium oxide becoming part of the glass and carbon dioxide being released. 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.

    Blowpipe

    An iron or steel tube, usually about five feet long, for blowing glass.g. The float process is now the standard method of producing sheet glass world-wide. The forming or application of figures or patterns to an object so that they stand out from the surface.

    Vello process

    A drawing process used for the production of glass tubing. When applied, the acid will corrode the glass but not attack the wax-covered areas. This allows the external layer to crystallize into a wider lattice while the inside solidifies with greater compression than in the crystal lattice. 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.

    Air trap, air lock

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

    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.

    Most offer advantages of low thermal expansion, making them suitable for uses such as cookware. Molten glass is fed into a steel mould which rotates at the required speed.

    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. One of the two principal types of optical glass used in the production of compound lenses.S.

    Push-up

    The base of a glass bottle (particularly of a wine bottle) which is pushed upwards inside the bottle during the forming process. Borosilicate glass is the most common type of heat resistant glass. At high speeds, the glass can assume almost cylindrical shapes.

    Mould, optic

    An open mould with a patterned interior in which a parison of glass is inserted, then inflated to decorate the surface.

    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. 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. Items to be polished are immersed in a mixture of demineralized water, sulphuric acid and hydrofluoric acid, and then rinsed.

     

     

    K

    Kiln

    An oven used to process a substance by burning, drying, or heating.

    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. 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.

    Infrared lamp

    An incandescent lamp working at a low filament temperature and consequently emitting relatively high amounts of infrared radiation. Fining agents induce the formation of large bubbles which collect smaller bubbles as they rise to the surface.

    Blow-and-blow process

    A production process used for glass container manufacturing with forming machines.), construction hollow ware (glass building blocks, etc. 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. 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. 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.

    Coating

    A thin layer which covers the surface of an object. machine more flexible than continuous- or intermittent-motion rotary machines. This is followed by a maturing period, during which the molten glass cools to a working temperature of about 2000°F (1100°C). The two main types are stearate- and polyethylene-based.

    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. This results in internal stresses which may cause the glass sheet or object to crack, shatter or even explode some time later. One way of producing a conductive coating is by depositing tin salts onto the glass. Glass is sucked from the tank of molten glass into the parison mould and then cut by shears. Molten glass is fed into a steel mould which rotates at the required speed.) and fluorescent lighting.

    Acid polishing

    A process used in the production of cut crystal to remove the opacity of etched surfaces where decoration has been applied.

    Embossing

    Carving or moulding in relief. The second medium normally used to establish the index is a vacuum. 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. The medium burns away during firing in a low-temperature muffle kiln (about 965-1300°F or 500-700°C).

     

     

    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).

    Considerable automation of the process has been developed, thus allowing extremely high printing speeds for even complex designs. Before being used in a batch, it is thoroughly washed, heated to remove carbonaceous matter, and screened to obtain uniformly small grains.

    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. The glass is then cut into the size required

    2.

    Vial

    A small cylindrical glass vessel especially for holding liquid medicines.1 mm).

    Cylinder glass

    A technique for producing sheet glass dating from the 11th century. Such glass has a high refractive index and is particularly suited for decoration by cutting.

    Staple fibre

    Short lengths of glass fibre, usually U-shaped, which intertwine and are used, in particular, to create insulation materials. 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.

    Firing

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

    Cold end

    The name given to the stage in glass production involving processing when the glass is cold.g. The drawing speed with the Libbey-Owens process is twice that of the Fourcault process. 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. 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.

    Pelletising

    The preparation of materials, e. 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.S.

    Plunger

    A tool used in the production of glass containers during the first stage of shape forming in the IS machine.

     

     

    T

    Tank

    A large receptacle constructed in a furnace for melting the batch. The glass worker gathers directly from the pot.

    Redox

    The abbreviated form of "reduction-oxidation".

    Libbey-Owens process

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

    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. It is used where transparency of the glass sheet is not important or not desired. batch ingredients, in pellet form (see also "pellet").

    Pyrometer

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

    Sand

    The most common form of silica used in making glass.

    During the shaping process in the IS machine, the neck ring transports the glass container into the blow mould (or finishing mould).

     

     

    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. For most present-day glassmaking, sand must have a low iron content.

    Crown glass

    1.

    Rolled glass

    Rolled (or cast) glass is a translucent glass with 50-80% light transmission, depending on its thickness and type of surface.

    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. Window glass blown into a crown or hollow globe that is flattened and cut before use.

    Polyethylene coatings are deposited from a water emulsion but are not water-soluble and can thus withstand washing and pasteurising.) and lighting glass (lamps, bulbs, etc.

    Lathes

    Two distinct types of lathe exist, although both basically consist of a horizontal shaft rotated by a motor. 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. The gobs are fed into the forming machine to be moulded into bottles and other glass objects. 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.g. 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.

    Soda ash

    Sodium carbonate (Na2CO3), or 'soda ash', is the main source of sodium oxide (Na2O), or 'soda'. Low-E glass thus allows light to enter while also providing thermal insulation.

     

     

    N

    Narrow-neck ware

    Glass containers, such as bottles, whose opening is tapered and of smaller diameter than the body of the vessel.

    Soda

    Sodium carbonate. This phase is followed by a period of cooling with a pre-defined temperature gradient.

    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).

    Chalcogenide glass

    Glass with electrical conductivity characteristics made with the addition of the chalcogen elements (sulphur, selenium and tellurium). Stearic acid is of vegetable origin, making this type of coating also suitable for kosher foods.

    Refining

    Refining ensures that a homogenous glass is produced during founding by eliminating bubbles (see also "bubbles"). The process of pressing glass was first mechanized in the United States between 1820 and 1830.

    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.

    Engraving

    The production of a design in glass by cutting into the glass surface.

    Silica

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

    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. The process was developed by an American engineer, Edward Danner, in 1912. 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.

    Glory hole

    A hole in the side of a glass furnace, used to reheat glass that is being fashioned or decorated. 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. During blowing, a vacuum is applied through the mould to suck any trapped air or other gases from the bottom of the mould.

    Acid etching

    This process for the decoration of glass involves the application of hydrofluoric acid to the glass surface. It is also used when glass has to be bonded to metal and low expansion is a key characteristic.

    Inspection for specific faults: cracks (also known as checks); stones; foreign material (tramps); spikes; birdswings; thin spots. (independent/individual section) container forming machines are made up of individual but identical sections placed side by side in line.

    Furnace, tank

    See Tank. 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.

    Preston test

    The means of verifying the bursting strength of a glass container during automatic inspection. The process may be physical (thermal) or chemical. 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). 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. The solid joining of the glasses takes place in a pressurised vessel called an autoclave. The term "redox equilibria" is used to refer to the balance between reduction and oxidation in the glass furnace. There may be a single short immersion in a stronger solution or, alternatively, a series of immersions in a weaker solution.

    Mixed feed

    The transfer of the various ingredients of the batch into the mixer by means of hoists, buckets and conveyor systems. Inleakage can result in decreased efficiency and increased fuel costs. 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. While still hot, the ends of the pod are cut off and the resulting cylinder cut lengthways and laid flat. Used for producing larger quantities of glass than is possible with pot furnaces (see "pot").

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

    Suck-blow process

    A process used for glass container manufacturing with forming machines. Polyethylene coatings are transparent and give high lustre and lubricity to the glass surface., 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. Conductive coatings have been used to produce frost-free windscreens, and in a range of electro-optical applications.

    Bending

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

    Suction cup

    A semi-spherical cup of flexible material such as rubber.), medico-technical glassware (laboratory equipment, tubing, etc.

    Borosilicate glass

    Glass made from silica and boric oxide. It serves as a flux to reduce the fusion point of the silica when the batch is melted. For example, a flux is added to the batch in order to facilitate the fusing of the silica. Some moulds (e.

    Containers, enameling

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

     

     

    S

    Safety glass

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

    Grinding

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

    Armour plate glass

    Laminated glass, resistant to mechanical shock, composed of at least four panes of glass and usually at least 25 mm thick.

    Tempering

    See toughening

    Thermal conductivity

    The passage of heat through a material.

    Fining

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

    Containers, defects

    Defects in automatically produced containers are categorized as very critical (Group 1), main faults (Group 2) and secondary (Group 3)
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