Abstract: A silver metallizing paste for attachment of silicon semi-conductive devices in lead-frame packages, specifically ceramic packages, which is less expensive than a gold preform but useable in hermetic packages, and provides better electrical and thermal conductivity, and higher bond strength, than silver polyimides. From 25 to 95% of silver is blended with a low-melting glass, preferably one having 95-96% PbO, and a paste or ink is formed with a suitable vehicle at 75-85% solids. Use of the paste follows conventional practice. Selection of Ag:glass ratio depends on the type of die bonding to be used. The paste is particularly useful in MOS technology, where low contact resistance is required, and also finds applications as a solder substitute and bonding chip capacitors. It is most advantageous in attachment of larger-area integrated circuits in that stress cracking associated with the gold-silicon eutectic is avoided.

Abstract: A thick-film multi-layer wiring board in which the thick-film resistor provided in the inner layer is coated with a glass material selected from (a) and (b) below:(a) crystallized glass which is crystallized at 850.degree. C. or above, and(b) amorphous glass having a softening temperature of 750.degree. C. or above and composed of glass and at least one refractory oxide selected from Al.sub.2 O.sub.3 and SiO.sub.2.

Abstract: A method for sealing a rim-like opening in a glass container is described. The surface of the opening is treated with tin and/or titanium oxide precursors and with or without one or more of the groups consisting of fluorides, sulfur oxides and sulfur oxide precursors and then overcoated with a chromium III organic metallic complex. A membrane comprising a thermoplastic film is pressed onto the coated opening surface and heated to cause glass-plastic adhesion, forming a closure. The coating steps may be applied to glass containers immediately after forming and annealing as appropriate, or may be applied to glass containers taken from storage.

Abstract: Improved air-fireable resistor and conductor inks useful in constructing multilayer integrated circuits on porcelain-coated metal substrates are provided. The subject inks comprise a barium calcium borosilicate glass frit, a suitable organic vehicle, and a functional component, i.e., ruthenium dioxide, in the resistor inks and one or more precious metals plus bismuth oxide in the conductor inks.

Abstract: Steel products may be coated with an insulating composition by a process which involves coating a uniform layer of finely ground glass powder on the steel and burning it at temperatures ranging from 700.degree.-1000.degree. C. Following, a paste comprising a mixture of the afore-mentioned glass, aluminum oxide and an evaporable liquid are deposited upon the burned coating, dried and burned again at 700.degree.-1000.degree. C.The resultant coatings adhere well to steel and resist temperatures as high as 860.degree. C., so suggesting then use for coating steel destined as a substitute for ceramic supports in electronic and hybrid microelectronic applications.

Abstract: A thick film is formed initially as a paste and made up of such oxidizable conductor ingredients as copper which is then mixed with glass frit and next printed on a non-conductive inert substrate by silk screening. The silk screen printed thick film with vehicle is then dried, and a coating of boron in suitable paste or paint form having been mixed with a thixotropic organic vehicle is covered over the entirety of the substrate and silk screen printed thick film. The resulting product after a second air drying is then fired to bond the glass frit-copper as a thick film onto the substrate, with the copper particles being sintered throughout into a thick film. Superposed boron, where contiguous with the copper printing, is fused as a protective layer over the copper allowing the sintering of the copper and bonding with the substrate to occur without oxidation of the copper.

Abstract: There is disclosed a composite photochromic glass article composed of a glass core and a thin surface layer substantially encasing that core, the core preferably containing a copper-cadmium halide photochromic crystal system and the substantially encasing glass layer preferably containing a copper-cadmium-silver halide photochromic crystal system. The article may be made by fusion laminating two separately formed glasses, or by introducing silver into a surface layer on a glass article by ion exchange.

Abstract: A vitreous enamel resistor material comprising a mixture of a vitreous glass frit and fine particles of tin oxide (SnO.sub.2). An electrical resistor is made from the resistor material by applying the material to a substrate and firing the coated substrate to a temperature between about 850.degree. C. and 1150.degree. C. at which the glass melts. Upon cooling, the substrate has on the surface thereof, a film of the glass having the particles of the tin oxide embedded therein and dispersed therethroughout. The resistor material provides a resistor having a resistivity within a wide range and a low temperature coefficient of resistance.

Abstract: A glazed ceramic substrate for use in electric or electronic devices, obtained by forming a glass coating layer directly on a major surface of a ceramic substrate such as an alumina substrate. The glass as the material of the coating layer contains 50-60 Wt % of SiO.sub.2, 10-30 Wt % of Al.sub.2 O.sub.3, 15-30 Wt % of CaO and MgO, and 2-6 Wt % of ZrO.sub.2 as essential components, optionally with the addition of small amount(s) of at least one of TiO.sub.2, BaO, ZnO, PbO, P.sub.2 O.sub.5, B.sub.2 O.sub.3, Na.sub.2 O and K.sub.2 O. The coating layer formed of this glass is excellent in its high-temperature stability, so that the glazed ceramic substrate is particularly suitable for use in thermal heads of thermal printing devices.

Abstract: A method for sealing a rim-like opening in a glass container is described. The surface of the opening is treated with tin and/or titanium oxide precursors and with or without one or more of the groups consisting of fluorides, sulfur oxides and sulfur oxide precursors and then overcoated with a chromium III organic metallic complex. A membrane comprising a thermoplastic film is pressed onto the coated opening surface and heated to cause glass-plastic adhesion, forming a closure. The coating steps may be applied to glass containers immediately after forming and annealing as appropriate, or may be applied to glass containers taken from storage.

Abstract: A high temperature stable and solar radiation stable thermal control coating either useful as such, applied directly to a member to be protected, or applied as a coating on a re-usable surface insulation (RSI) has a base coat layer and an overlay glass layer. The base coat layer has a high emittance, and the overlay layer is formed from discrete, but sintered together glass particles to give the overlay layer a high scattering coefficient. The resulting two-layer space and thermal control coating has an absorptivity-to-emissivity ratio of less than or equal to 0.4 at room temperature, with an emittance of 0.8 at 1200.degree. F. It is capable of exposure to either solar radiation or temperatures as high as 2000.degree. F. without significant degradation. When used as a coating on a silica substrate to give an RSI structure, the coatings of this invention show significantly less reduction in emittance after long term convective heating and less residual strain than prior art coatings for RSI structures.

Abstract: Improved resistor inks useful in constructing multilayer integrated circuits, particularly on porcelain-coated metal substrates, are provided. The subject inks comprise: a conductive component consisting of stannous oxide and molybdenum trioxide or a mixture of molybdenum trioxide and metallic molybdenum; a glass powder selected from the group consisting of a barium aluminum borate glass and a barium calcium borosilicate glass; and a suitable organic vehicle.

Abstract: A vitreous enamel resistor material comprising a mixture of a vitreous glass frit and fine particles of tin oxide (SnO.sub.2). An electrical resistor is made from the resistor material by applying the material to a substrate and firing the coated substrate to a temperature at which the glass melts. The tin oxide is preferably heat treated prior to mixing with the glass frit. Upon cooling, the substrate has on the surface thereof, a film of the glass having the particles of the tin oxide embedded therein and dispersed therethroughout. The resistor material provides a resistor having a wide range of resistivity and a low temperature coefficient of resistance.

Abstract: Improved construction material especially suitable for use in the manufacture of soundboards and panels used in stringed instruments which equal or surpass the sound radiation qualities and physical properties of wood. The construction material of the invention includes fibers having a Young's modulus of elasticity greater than 18.times.10.sup.11 dynes/cm.sup.2 and a density less than 2 g/cc bonded to a material having a density lying within the range of 0.15 g/cc and 1 g/cc, the said fibers of the composite are oriented in such manner so as to provide a final material having a bending stiffness ratio of at least 4:1.

Abstract: A process of bonding a plurality of thermally stable, high strength graphite fiber reinforced glass matrix composite materials is described. The process comprises applying to the surface of at least one of the composite materials to be bonded, a mixture of low softening point glaze such as high lead oxide containing glaze, a high melting point low coefficient of thermal expansion material such as beta-spodumene and colloidal silica followed by hot pressing the composite materials to be bonded together. The resultant bonded articles and the glass compositions particularly adapted for this bonding process are also described.

Abstract: The reflector of the present invention is the one in which on a substrate are successively arranged a resin layer, preferably, a resin layer having a molar percentage of an aryl group/(alkyl group plus aryl group) is 65-100%, a vacuum deposited layer of a light reflective metal and a light transmissible crystalline ceramic layer in this order. Pinholes or non-smoothness on the substrate is eliminated by disposing the resin layer on the substrate, and a vacuum deposited layer of a light reflective metal having a smooth surface is easily obtained. And on the surface thereof is disposed a vacuum coated layer of the light transmittable crystalline ceramic, and hence, without taking the reflector out of a vacuum depositor, it can be vacuum deposited continuously and its manufacture is very easy.

Abstract: An article with multi-layer protective coatings, comprising a substrate and two protective coating layers, in which said protective coating layers consist of a vacuum-coated ceramic layer and a resin layer, coated in any desired order.

Abstract: The reflector of the present invention is a multi-layer reflector comprising a substrate with or without a resin layer coated thereon; a light-reflective metal layer vacuum-coated on said substrate; and a protective layer consisting of a light transmittable resin layer and a light transmittable, preferably vacuum-coated, inorganic substance layer coated on said metal layer. By this, each film can be thin as compared with each individual protective film, which leads to good heat conductivity low temperature rise, high impact strength and good durability and which gives clear reflected images or high precision light collective and light distributing properties. In addition, the coated light-reflective metal shows better regular reflectivity, giving clear and sharp reflected images and allowing more accurate light collective or light distributing properties.

Abstract: There is disclosed a borosilicate, opal glass article composed of a phase-separated, opacified interior portion completely encased within, and integral with, a transparent, single-phase glass, surface skin. The phase-separated portion contains borate-rich and silicate-rich phases so different in refractive index that light is scattered, and the glass may contain a titania-coupled colorant. The article may be produced by molding a glass charge while simultaneously extracting heat from a surface layer on the molded article to maintain such surface layer as a single-phase glass.

Abstract: A method for preparing a glass container, and for sealing a glass mouth of a container and the seal are described. The sealing surface, or finish, of the container is subjected to a hot end treatment after forming and before annealing to enhance adhesion between the container finish and a thermoplastic membrane seal. The container is next annealed and after annealing is subjected to a cold end treatment in which the exterior container surface is coated with a material which enhances the lubricity and increases the abrasion and scratch resistance of the container. The container finish only is then subjected to a brief heat treatment sufficient to remove any lubricity enhancing material from the finish. A membrane comprising a thermoplastic film is pressed onto the container finish and heated causing glass-plastic adhesion and forming a closure.

Abstract: Concentrated boric anhydride solutions containing more than 5% of boric anhydride in an organic solvent selected from mono or polyalcohols, trialkylborate and/or dialkylacetal when the solvent also contains an acid selected from sulfuric acid and/or aromatic acids. These solutions are used as hardeners of formo-phenolic resols, more particularly for the manufacture of laminates comprising glass fibers and formo-phenolic resols.

Abstract: A vitreous enamel resistor material comprising a mixture of a vitreous glass frit and fine particles of tin oxide (SnO.sub.2). An electrical resistor is made from the resistor material by applying the material to a substrate and firing the coated substrate to a temperature at which the glass melts. The tin oxide is preferably heat treated prior to mixing with the glass frit. Upon cooling, the substrate has on the surface thereof, a film of the glass having the particles of the tin oxide embedded therein and dispersed therethroughout. The resistor material provides a resistor having a wide range of resistivity and a low temperature coefficient of resistance.

Abstract: A glass container having an upper rim for dispensing the contents thereof and a sealing membrane adapted to be applied to said rim to seal the contents of the container. The sealing surface of the container is prepared by treatment with fluorine and a metal oxide, or a sulfur oxide and a metal oxide, or with fluorine alone or a sulfur oxide alone, at an elevated temperature. To form the closure a membrane comprising a thermoplastic film is applied over the sealing surface and heated to result in a glass/plastic adhesion. The membrane may be a thermoplastic polymer/aluminum foil laminate.

Abstract: A glazing paste comprising glass frit, a metal oxide powder selected from the group consisting of aluminum oxide (Al.sub.2 O.sub.3), magnesium oxide (MgO), calcium oxide (CaO), and zinc oxide, (ZnO), and an organic vehicle.

Abstract: Air fireable nickel boride-based end termination compositions for multilayer capacitors are provided. The nickel boride compounds utilized are either (Ni.sub.3 B).sub.a (Ni.sub.3 Si).sub.b or Ni.sub.3 B.sub.1-x P.sub.x and the compositions also contain a glass whose component oxides have a redox potential of less than -0.5 volt. These compositions, upon firing, afford conductors such as end terminations in multilayer capacitors having excellent solderability and solder leach resistance, adhesion to dielectric substrates and electrical properties substantially equivalent to standard silver/palladium conductors.

Abstract: A method for producing a corrosion-, heat- and oxidation-resistant material hich comprises coating a substrate composed of at least one material selected from metals, carbonaceous substances and ceramics with a semi-inorganic compound, and heat-treating the coated substrate; said semi-inorganic compound being either(1) a modified organoborosiloxane compound obtained by reacting an organoborosiloxane compound with at least one organic compound selected from the group consisting of polyhydric aliphatic alcohols, aromatic alcohols, phenols and aromatic carboxylic acid at a temperature of from 250.degree. to 450.degree.

Abstract: Ceramic articles are provided with cadmium red-based decorations of improved chemical durability, by firing the decorations onto the articles at high temperatures. The cadium red-based enamels used for decoration are protected against color burn-out during high-temperature firing by a color stabilizing agent consisting of a fritted, sinterable, devitrification resistant alkali borosilicate glass which is combined with the enamels prior to firing.

Abstract: A method for preparing a glass container, and for sealing a glass mouth of a container and the seal is described. The sealing surface of the container is prepared by treatment with fluorine and a metal oxide, or a sulfur oxide and a metal oxide, or fluorine alone or a sulfur oxide alone, at an elevated temperature, in the case of fluorine employing a fluoride compound which decomposes at the temperature and, in the case of a metal oxide employing a metal oxide precursor. To form the closure, a membrane comprising a thermoplastic film is pressed over the sealing surface and heated to result in glass-plastic adhesion. The membrane may be a thermoplastic polymer/aluminum foil laminate.

Abstract: Air-fireable thick film conductor compositions are provided. The conductor composition is a paste containing (1) an inorganic powder made from an intermetallic phase copper-aluminum powder, aluminum powder and a glass frit and (2) an inert organic liquid vehicle.

Abstract: A cooking utensil having a body sheet of iron base metal with a non-stick coating tenaciously secured to the surfaces thereof that are presented toward foods to be cooked, the non-stick coating being of composite construction including an inner layer and intermediate layer and an outer layer, the inner layer consisting essentially of a porcelain enamel ground coat providing protection for the adjacent surface of the body sheet, the intermediate layer consisting essentially of a porcelain enamel cover coat adhered both to the inner layer and the outer layer and providing resistance to wear and abrasion, the outer layer consisting essentially of a non-stick plastic material adhesively bonded to the adjacent surface of the intermediate layer.

Abstract: A heat resistant protective coating for a metal surface comprises a glass matrix having at least 50 percent by weight of finely divided metallic particles dispersed therein. The coating is produced by covering the metal surface with a mixture containing 40 to 60% by weight of finely divided metallic particles, 17 to 40% by weight of a ceramic frit and from 10 to 18% by weight of an organic resin, and heating the thus coated surface in air to burn off the organic resin and fuse the frit.

Abstract: A glass for edge-cladding a disc laser glass, comprising, in mol%, followed in parentheses by wt % value,______________________________________ P.sub.2 O.sub.5 46- 63, (64-76) Al.sub.2 O.sub.3 4- 8, (3.5-7.5) B.sub.2 O.sub.3 0- 5, (0-3.0) K.sub.2 O 2- 20, (2.5-16.5) Na.sub.2 O 0- 15, (0-8.5) Li.sub.2 O 0- 14, (0-3.5) K.sub.2 O + Na.sub.2 O + Li.sub.2 O 18- 30, (11.5-20.5) CuO 2- 20, (1.4-13.5) ZnO 0- 15, (0-11.5) MgO 0- 5, (0-2.0) and CuO + ZnO + MgO 7- 20. (4.7-13.5).

Abstract: A vitreous enamel resistor material comprising a mixture of a glass frit, and fine particles of tin oxide (SnO.sub.2), a primary additive of particles of oxides of manganese, nickel, cobalt or zinc, and a supplemental additive of oxides of tantalum, niobium, tungsten or nickel. An electrical resistor is made from the resistor material by applying the material to a substrate and firing the coated substrate to a temperature at which the glass melts. The tin oxide may be heat treated prior to mixing the glass frit. Upon cooling, the substrate has on the surface thereof, a film of the glass having the particles of the mixture embedded therein and dispersed therethroughout. The resistor material provides a resistor having a wide range of resistivities and a low temperature coefficient of resistance.

Abstract: A light-transmitting fire screening panel comprising at least one sheet of glass and at least one layer of intumescent material, the improvement which comprises utilizing in the layer a hydrated alkali metal silicate as intumescent material and one or more adjuvants selected from: urea, polyhydric alcohol (including glycerine, ethylene glycol and sorbitol), monosaccharide (including glucose), polysaccharide (including starch), sodium phosphate, sodium aluminate, aluminum phosphate, borax, boric acid and colloidal silica.

Abstract: Particulate perlite fines are agglomerated to increase the apparent particle size by forming a mixture of the perlite fines with a compound such as boric acid capable of being substantially converted to B.sub.2 O.sub.3 at elevated temperatures. The mixture is heated while mixing to convert the compound to B.sub.2 O.sub.3 and to at least partially coat the particulate perlite.The mixture is then heated above the melting point of B.sub.2 O.sub.3 to agglomerate the perlite fines. The product of this process has particular utility as an improved filter aid.

Abstract: A material for a vitreous enamel electrical resistor includes a mixture of a glass frit and particles of nickel, iron and cobalt. The material is applied to a substrate and fired to melt the glass frit, and then cooled to form a layer of the glass with particles of an alloy of nickel, iron and cobalt embedded therein. The material provides a resistor having a high temperature coefficient of resistance and which can be self terminating.

Abstract: A thermal printing head having a substrate and a resistive element formed on the substrate wherein said resistive element is a thin layer which is composed of an electrically conducting material and an electrically insulating material. This thermal printing head has a high heat-resistivity, so that it may be used at a high temperature or for high speed printing.

Abstract: An electrically nonconductive copper-boron coating is deposited on a nonmetallic surface such as glass by reducing a copper salt with a small amount of alkali metal borohydride in the presence of a complexing agent such as Rochelle salt or ethylenediamine tetraacetate salts. The resultant copper-boron coated article may subsequently be heated until it acquires a copper-bronze appearance by reflection.

Abstract: The invention disclosed is a family of enamel fluxes that forms the basis for enamels used in decorating opal glasses where the glasses have softening points in excess of 760.degree. C. and coefficients of thermal expansion (25.degree.-300.degree. C.) of 70-85.times.10.sup.-7 /.degree. C. The enamel fluxes have softening points in the range of 550.degree.-575.degree. C., toxic metal release values below FDA prescribed standards, coefficients of thermal expansion in the range of 65-75.times.10.sup.-7 /.degree. C. and preferably at least 5 units below the coefficient of the opal glass, and fire to a high gloss in a firing cycle of less than 10 minutes having a maximum temperature below 720.degree. C. They have compositions that form a family in the Li.sub.2 O-Na.sub.2 O-B.sub.2 O.sub.3 -TiO.sub.2 -CdO-ZrO.sub.2 -PbO-SiO.sub.2 system.

Abstract: There is disclosed a glass or glass-ceramic body with a coefficient of thermal expansion below 40.times.10.sup.-7 /.degree. C. and having an adherent, high gloss enamel fired on at least a portion of the external surface of the body, the enamel flux being composed, in percent by weight on a calculated oxide basis, of 25-40% SiO.sub.2, 40-60% PbO, at least 75% PbO+SiO.sub.2, 3-10% ZrO.sub.2, 4-12% B.sub.2 O.sub.3, and 0.2-2.0% Li.sub.2 O, being free of TiO.sub.2, optionally containing up to 2% Na.sub.2 O+K.sub.2 O and up to 4% CdO, having a coefficient of thermal expansion of 48-70.times.10.sup.-7 /.degree. C., a softening point below 660.degree. C. and low lead and cadmium release values under either acid or alkaline conditions.

Abstract: A seal structure consisting of a ceramic base and a low-expansion metallic material bonded by a low-melting glass particularly useful for large scale integrated circuit (LSI) applications is disclosed. When using a high alumina ceramics containing 65 to 92% of Al.sub.2 O.sub.3 by weight as a ceramic, the thermal coefficients of expansion are best matched while maintaining a comparatively low dielectric constant by using a composition consisting of 60 to 85% lead borate glass, 10 to 30% .beta.-eucryptite and 0.5 to 15% zircon as a low-melting sealing glass.

Abstract: A paste for forming a thick film conductor of a base metal on a non-conductive substrate comprises a base metal powder (particularly nickel) which ordinarily would oxidize when fired in air, boron powder and a vehicle. In one embodiment, the paste may also contain glass frit. By proper selection of the composition, in particular the amounts of boron and glass frit, a base metal conductor can be formed which strongly adheres to the substrate and has excellent conductive properties. Ranges of compositions are disclosed within which the pastes can be fired in air and produce conductive thick films and outside which conductive properties are inferior and/or the bond strength is unsatisfactory.

Abstract: A composite glass article for channel plate fabrication comprising a glass matrix in which is encased an array of leachable glass core elements, the core elements being composed of a BaO-B.sub.2 O.sub.3 -SiO.sub.2 glass exhibiting improved leaching characteristics as well as thermal expansion and high temperature softening properties compatible with the glass matrix, is described.

Abstract: Sealing glass compositions are provided as sealants for copper-aluminum alloys.

Abstract: Metallizing compositions suitable for the production of fired on electrically conductive films which do not adversely affect the overall strength of heat resistant substrates are described. The compositions comprise, in specified proportions, at least one finely divided electrically conductive metal, certain alkali metal, crystallizable, high silica glass frits as binder, inert liquid vehicle and, if desired, inert filler and/or pigment. The compositions are particularly suited to glass substrates and provide therewith composite structures having greater strength than that of the glass substrate.

Abstract: Cobalt boride conductor compositions of certain cobalt borides and, optionally, inorganic binder, dispersed in a vehicle and fireable in air to produce conductive films on substrates. Also the resultant sintered (fired) films.

Abstract: The present invention relates to reaction cured glass and glass coatings prepared by reacting a compound selected from the group of substances consisting of silicon tetraboride, silicon hexaboride, other boron silicides, boron and mixtures thereof with a reactive glass frit composed of a porous high silica borosilicate glass and boron oxide. The glassy composites of the present invention are useful as coatings on low density fibrous porous silica insulations used as heat shields and for articles such as reaction vessels that are subjected to high temperatures with rapid heating and cooling and that require resistance to temperature and repeated thermal shock at temperatures up to about 1482.degree. C (2700PF).

Abstract: A substrate, such as a ceramic body, carries a layer of glaze consisting essentially of (a) an inorganic oxide glass matrix that is essentially free from ions which migrate in a high-electric field, (b) about 1 .times. 10.sup.19 to 50 .times. 10.sup.19 antimony cations distributed in each cubic centimeter of the glass matrix, and (c) about 4 to 30 weight percent with respect to the weight of said glaze of discrete tin-oxide particles in the antimony-containing glass matrix. The method comprises dissolving antimony, as a compound thereof, in a glass, mixing together particles of said glass and tin-oxide particles, coating the mixture on a substrate, heating the coated substrate to melt the glass particles while retaining tin oxide in discrete particulate form, and then solidifying the molten coating.

Abstract: An electrically nonconductive copper-boron film is deposited on the surface of a substrate, particularly a nonmetallic substrate such as glass, by reducing a copper salt with a small amount of alkali metal borohydride in the presence of a complexing agent such as Rochelle salt or ethylenediamine tetraacetate salts. The resultant copper-boron coated substrate may be further heated until it assumes a copper-bronze appearance by reflection, resulting in a copper-boron coated article, or the copper-boron coated substrate may be subjected to chemical reduction, resulting in a copper coated article of superior uniformity.

Abstract: A fire screening glazing panel and a method of producing same. A panel is formed of at least two structural plies and at least one of which is a vitreous sheet, layers of heat convertible thermally insulating barrier forming material are placed on a face of each ply, and a plastic membrane is sandwiched between the layered plies, the layers being adjacent the plastic membrane. When formed in this way, the plastic membrane makes the transfer of heat from one barrier-forming material layer to the other more uniform and prolongs the time taken for the vitreous sheet to reach a given temperature, while the panel as a whole is in itself sufficient to prevent or delay propagation of fire across an opening closed by the panel. Protective strata may be applied to each vitreous ply on its face that will be in contact with the barrier forming material layer to inhibit interaction between the ply and the layer and preserve the transparency (if the ply is transparent) of the ply over an extended period of time.