Abstract: A method of making and improving a coating formulation which includes a hydraulic binder. To the formulation is added a quantity of dewatering agent. The resultant slurry produced from said formulation may be applied to the product to be coated and dewatered through said product. Dewatering can be accomplished with or without vacuum assistance.

Abstract: The present invention provides a mixer and a mixing method which enable stable supply of slurry at a high flow rate with foam being uniformly mixed therein, and which enable reduction in consumption of foam to be fed to the slurry. The mixer (10) has a housing (20), a rotary disc (32), a slurry outlet port (45), a slurry delivery conduit (46) and a hollow connector section (47). A foam feeding port (41) is disposed in a predetermined position of an annular wall or the hollow connector section. The foam feeding port feeds the foam to the slurry, immediately before the slurry enters the slurry outlet port, or feeds the foam to the slurry in the hollow connector section. The slurry and the foam mix with each other at the slurry outlet port or on its downstream side. The foam is not substantially subjected to agitation impact of the mixer and a quantity of loss of the foam is reduced.

Abstract: A method for generating foam for gypsum product manufacturing includes injecting water through a conduit and injecting a foaming agent through the conduit to form a first solution comprising the water and the foaming agent. The method includes straining the first solution in the conduit and injecting air through the conduit to form a second solution comprising the water, the foaming agent and the air. The method also includes straining the second solution in the conduit to form foam and communicating the foam to a gypsum product manufacturing device.

Abstract: A shear panel building material that includes a first facing membrane, a core matrix disposed on a face of the first facing membrane, and a semi-rigid or rigid material attached to the core matrix. The core matrix can include microspheres having a size of about 200 microns to about 800 microns, sodium silicate, and ethylene vinyl acetate. In one aspect, the shear panel is substantially free from glue and cement.

Abstract: A coalescing additive is used in the manufacturing process for gypsum wallboard. Such an additive increases the surface area and density of the slurry at the paper to core interface by coalescing the foam cells away from the paper core interface. This permits a stronger paper to core bond to form and increases the compressive strength of the gypsum wallboard as compared to standard wallboards made from slurries with reduced water levels.

Abstract: A process employing a wet mixer having a vertical mixing chamber for forming a wet slurry of a cementitious powder and liquid. The vertical mixing chamber is designed to provide the required amount of mixing to provide thoroughly mixed, uniformly thin slurry within a mixing residence time that allows for adequate supply of slurry to ensure continuous operation of an associated cement panel production line. Gravity feed for supply of cementitious powder and water to the slurry mixing area of the chamber is also disclosed.

Abstract: A wet mixer apparatus and method for its use, the mixer having a vertical mixing chamber for forming a wet slurry of a cementitious slurry and water. The vertical mixing chamber is designed to provide the required amount of mixing to provide thoroughly mixed, uniformly thin slurry within a mixing residence time that allows for adequate supply of slurry to ensure continuous operation of an associated cement panel production line. Gravity feeding for separate supply of cementitious powder and water to the slurry mixing area of the chamber without pre-mixing of the powder and water is also disclosed.

Abstract: The present invention relates to a system and associated method for the production of gypsum in manufacturing plant. More specifically, the invention relates to the production of alpha-type gypsum in a gypsum board manufacturing plant. The system yields increased efficiencies by capturing heat given off during processing steps and using that heat to reduce the energy needed for calcination. The invention finds particular application in the production alpha-type gypsum. The present invention is described in greater detail hereinafter in conjunction with the following specific embodiments.

Abstract: A gypsum composition for use as a wallboard core contains stucco, water, a styrene acrylic or acrylic hybrid copolymer, and a reduced amount of starch. A finished wallboard using this composition has similar properties, including compressive strength and paper core bond strength of a finished board, to wallboards made from compositions having higher quantities of starch. A method for producing such a composition is shown, the method requiring mixing of stucco and pulp water in a pin mixer, with the addition of starch and the styrene acrylic or acrylic hybrid copolymer.

Abstract: A method is provided which uses an improved emulsion to imparting water-resistance to gypsum products. In one embodiment, gypsum products comprise calcium sulfate dihydrate and an emulsion which comprises a saponified wax, a nonsaponifiable wax, an alkyl phenol, a surfactant/dispersant salt of polynaphthalenesulfonic acid, and carboxymethylcellulose. Optionally, the emulsions may contain a preservative, e.g., a biocide (mildewcide, fungicide, etc.). These gypsum products resist the uptake of water and therefore resist biological infestation without addition of a preservative.

Abstract: A process for manufacturing plasterboard and a plasterboard manufacturing unit are provided, the process including feeding hydratable calcium sulphate and water into a first mixer (2) and into a second mixer (3); feeding in a facing (5); preparing a first gypsum slurry in the first mixer (2); preparing a second gypsum slurry in the second mixer (3); applying the first slurry onto the facing and forming a crude surface layer; applying the second slurry onto the crude surface layer and forming a crude core layer with a density lower than that of the crude surface layer; forming a plasterboard; hydrating and drying the board. This process allows the formation of the different layers of gypsum to be controlled independently.

Abstract: The acoustical product of the present invention comprises an acoustical product including a matrix of calcium sulfate dihydrate crystals and expanded perlite distributed throughout the matrix. The expanded perlite has a particle size distribution with at least 10% of the perlite having a particle diameter of 700 microns or more, and the amount of expanded perlite to calcium sulfate dihydrate is about 35% to about 75% by weight, based upon the dry weight of the calcium sulfate dihydrate. A dispersing agent and glass fibers having a particle length of about ¼ inch to about 1 inch are dispersed throughout the gypsum matrix.

Abstract: A sample support, which is configured in the form of a titre plate or chip. has a plastic support plate and several recesses for receiving samples. Said recesses are sealed with a glass plate. According to the present disclosure, a support core surrounding the recesses is embedded in the support plate in order to prevent contraction during the process for producing the support plate. The support core is preferably a metal plate with areas which have not been extrusion-coated, for use as contact surfaces. Heat can be introduced into the titre plate through these contact surfaces.

Abstract: Repulped fiber that has been treated with an aqueous solution of a caustic selected from sodium hydroxide, potassium hydroxide and sodium carbonate, is used to make wallboard paper that is used to make a gypsum wallboard having improved nail pulling strength compared to gypsum wallboard made with fiber wallboard paper that has not been treated with caustic.

Abstract: A method of manufacture of multilayer gypsum board, and a gypsum additive delivery system, including wet gypsum board passing through a board forming station in which additives are delivered to one or more layers of a multi layered gypsum board panels, such as engineered polymers, providing a better and more water resistance surface. Preferably, the gypsum board has a first layer of a mixture of set gypsum having an outer surface and a polymeric compound or wax emulsion additive entrained therein and impregnated in a thin sheet of randomly aligned inorganic fibers to essentially encase the core gypsum within two facing layers.

Abstract: A cover stock supply system for continuously feeding cover stock to a wallboard production line includes: a plurality of cover stock cradles for receiving rolls of cover stock; a splicing table; a cover stock cutter disposed between the cover stock cradles and the splicing table. The cover stock cutter has a positioning loop around a cover stock feed path and a cutting cable attached to the positioning loop. Cutter is configured and adapted to rotatably deploy the cutting cable from the drawn position on a first side of the cover stock feed path to a re-set position on a second side of the cover stock feed path upon motion thereof around the cover stock feed path.

Abstract: Articles, including fiberboard, are made from a pumpable, flowable slurry including alpha-calcined calcium sulfate hemihydrate anchored in pores of host particles, alpha-calcined calcium sulfate hemihydrate, a silicone compound, magnesium oxide, and water. The magnesium oxide catalyzes the reaction of the silicone compound into a silicone resin. In a preferred method of making a water resistant fiberboard calcium sulfate dihydrate is combined with the host particles and water to form a slurry which is heated under pressure to calcine the calcium sulfate dihydrate to form alpha-calcined calcium sulfate hemihydrate. After relieving the pressure, a silicone compound and magnesium oxide are added to the slurry. The slurry is dewatered to form a filter cake, which is then formed into a desired shape and allowed to set.

Abstract: A gypsum slurry includes calcium sulfate hemihydrate, water and calcium sulfate dihydrate, where the calcium sulfate dihydrate is added downstream of the mixer. In an optional embodiment, the a gypsum slurry includes calcium sulfate hemihydrate, a polycarboxylate dispersant, water and coated calcium sulfate dihydrate. In this case, the hydrophilic, dispersible coating is selected to serve as a modifier to enhance the ability of the dispersant to fluidize the gypsum slurry.

Abstract: A gypsum composition comprising water, stucco, clay, an amine compound, a polyoxyalkylene, and a comb-branched copolymer is disclosed. The gypsum composition has improved fluidity. A method for preparing the gypsum composition is also disclosed. The method comprises mixing the components to form a slurry, casting the slurry into a product, and drying the product.

Abstract: This invention is directed to a method of reducing the water demand of expanded perlite that includes obtaining a vibrating screen supported at an angle and placing expanded perlite on the vibrating screen. The expanded perlite is moved over the screen past toward a burner at a rate that heats the expanded perlite to a temperature sufficient to anneal it. The expanded perlite is then moved away from the burner and allowed to cool. Another embodiment of this invention is directed to a method of making a gypsum product. The method includes annealing perlite by the method described above, then preparing a slurry of calcium sulfate hemihydrate, additives, water and the annealed perlite. The slurry is formed into the shape of the gypsum product and allowed to set. This process is particularly useful in making gypsum panels and acoustical panels that benefit from the use of lightweight materials.

Abstract: An acoustical panel comprising a continuous phase of an interlocking set gypsum matrix and a method of preparing an acoustical panel are disclosed.

Abstract: A method of continuously forming a multilayer panel includes making a gypsum slurry, then dividing the gypsum slurry into at least a primary gypsum slurry and a secondary gypsum slurry. An additive slurry having water and an intumescent material is created, then added to the secondary gypsum slurry to make an expandable layer slurry that is spread over at least a portion of a facing material. The primary gypsum slurry is distributed over the secondary gypsum slurry over the facing material and the expanding layer slurry to form a core. Optionally, another layer, an edge coating, is applied to the expanding layer for additional fire protection. The edge coating includes a second intumescent material. During a fire, the expanding layer expands to increase the thickness of the fire exposed gypsum panel and the edge coating expands to seal the gap between adjoining gypsum panels.

Abstract: A method of forming a gypsum-based panel product including the steps of: mixing calcined gypsum, water, a foaming agent and a core strengthening agent to form a foamed slurry; depositing the slurry; shaping the slurry to form a board having a core and core surfaces, optionally sandwiched between sheets of liner; and allowing the core to set, and drying the board, wherein the strengthening agent is dextrin, used in an amount not less than 0.1% by weight, based on the amount of calcined gypsum, so that, after drying, there is provided a strengthening dispersion of dextrin throughout the core. Less than 5% dextrin in preferred.

Abstract: In at least one embodiment, the present invention relates to a gypsum composition suitable for use in the manufacture of construction materials comprising a) gypsum, b) water, and c) a water repellancy composition comprising a hydroxy-based cellulose and a siliconate.

Abstract: Process for the manufacture of plasterboards exhibiting a core density of less than 0.77 comprising the stages of the formation of a foam from water and a surfactant composed of at least one alkyl sulphate of formula H(CH2)nOSO3?M+, in which n is a number between 6 and 16, M is a monovalent cation and the mean number of carbon atoms nm is from 9 to 10, and the introduction of the foam obtained into a plaster slurry, characterized in that the amount of surfactant introduced does not exceed 0.32 g/l of plaster slurry. Application to the manufacture of lightened plasterboards.

Abstract: An apparatus and method for applying reference or grid markings to wallboard during the manufacturing process is disclosed. Reference or grid markings are applied to one sheet of cover paper at a location between the originating cover paper rolls and the cover paper creaser or creasers. This is accomplished by locating and aligning multiple print heads across the width of the continuously passing cover paper, such that markings are ejected onto the cover paper in a specific and coordinated fashion. In addition to using any suitable commercially-available computer equipment to coordinate printer head activity, this function is accomplished by attaching each print head to a common horizontal support element and provide individual adjustments that are perpendicular to, and with the directional flow of the passing cover paper.

Abstract: A jointing compound or plaster for construction elements, particularly paper-faced plasterboards. This plaster includes, in percentages by weight with respect to the total weight of plaster 50 to 85% of a mineral filler; 1 to 20% of an organic binder dispersible in an aqueous phase; 1 to 15% of a silicate-based agent other than the mineral filler; 0.2 to 5% of a hydrophobic agent which is a silicone derivative; 0.05 to 5% of polyvinyl alcohol; and water to make up to 100%. A method of producing a work such as a partition, a wall covering or a ceiling is also disclosed.

Abstract: A gypsum composition including gypsum, water, and a surfactant composition of alkyl sulfates of formula H(CH2)nOSO3?M+, in which n is from 6 to 16, the mean number of carbon atoms in the alkyl sulfate composition nm being between 10 and 11, and M is a monovalent cation. A process for the preparation of the gypsum composition and a gypsum board obtainable from this composition. Finally, a process for the manufacture of gypsum boards. Application for the manufacture of foamed gypsum boards.

Abstract: A multiple layer fiber reinforced material and method of constructing the same including the provision of a first layer of a roll lofted glass material. Optional variants include the pre-application of plywood, OSB or fiber reinforced cement board materials prior to the first glass layer. A layer of a rolled fiber reinforced material is applied over the rolled glass material, with or without backing board material, and at least a second layer of the roll lofted glass material is applied over the rolled fiber reinforced material. A layer of a second rolled glass material is applied over the subsequent layer of the first glass material and a urethane resin syrup is intermixed with said layers of glass material and the fiber reinforced material. An application of heat and pressure results in the formation of the reinforced material. A flexural, closed cell foam material may also be applied to provide acoustical insulating properties to the multi-layer fiber material.

Abstract: A mold-resistant gypsum panel includes a core of an interlocking matrix of calcium sulfate dihydrate crystals, a facing material on at least one side of the panel and a salt of pyrithione dispersed through both the core and the facing materials. A method of making a mold-resistant gypsum product is also provided. A slurry of calcined gypsum, water and a water-soluble pyrithione salt is formed, then deposited on a sheet of facing material. The slurry on the facing material is shaped into a panel and maintained under conditions sufficient for the calcined gypsum to react with the water to form a core comprising an interlocking matrix of set gypsum crystals. Heating of the panel causes evaporation of the water that did not react with the calcined gypsum.

Abstract: The present invention describes an improved building material composition, useful for example as a fire door core and to improved methods of making this composition. The building material of the present invention is prepared from an aqueous mixture of expanded perlite and a fast setting, cementitious composition consisting essentially of a hydraulic cement having (1) a Portland cement and (2) a calcium aluminate cement, which composition can be molded and shaped into a fire door core.

Abstract: A gypsum board comprises a set gypsum layer having a first face and a second face. A fibrous mat is affixed to at least one of the faces. The mat comprises a non-woven web bonded together with a resinous binder. The web comprises a blend of a major portion composed of chopped continuous glass fibers having an average fiber diameter ranging from about 8 to 17 &mgr;m and a minor portion composed of fine staple fibers having an average fiber diameter of less than about 5.5 &mgr;m, the minor portion comprising about 1-30 percent of the dry weight of the web. The board is exceedingly durable. It has a smooth surface that is readily finished in an aesthetically pleasing way, using paint or other wall covering systems.

Abstract: A method of resisting corrosion of metal elements in concrete is provided. It includes introducing into concrete containing metal elements, at least one combination compound capable of sequestering chloride ions having the formula 3Me(II)O.(R, R′)2O3.Me(II)(anion)2.nH2O, where R and R′ are different and are independently selected from the group consisting of Al, Fe and Cr; anion is selected from the group consisting of NO2, NO3 and OH, n is 0 to 24, and Me(II) is a cation and is selected from the group consisting of Ca, Ba, Sr, Mn, Zn and combinations thereof. In one embodiment of the invention, concrete structures may be rehabilitated by providing an overlay containing the combination compound, with the overlay being provided in situ or as a preformed member and with possible use of a slurry in combination with an overlay segment.

Abstract: In some embodiments, alternate sources of aluminum or calcium are provided in various ways including the desired compounds. The further object of the present invention contemplate in situ creation of the compound in interest in fresh concrete and as a slurry which can be employed in remediation of existing concrete structures. A method of resisting corrosion in concrete containing metal elements is provided. It includes introducing into fresh concrete, containing metal elements, at least one compound capable of sequestering chloride ions. The method may also involve employing a compound which is capable of establishing a corrosion resistant oxide layer on the metal reinforcing elements. The invention also includes certain compounds which may be employed in the method as well as concrete structures containing the compounds.

Abstract: Cement wallboards and methods for their preparation are disclosed. The wallboards comprise two scrim layers and one mat layer. The wallboards have a smooth surface, are strong, lightweight, and easy to score and snap. Tiles can be readily adhered to the boards. The wallboards can be used in general commercial and residential construction, and are particularly attractive for use in high water/moisture areas such as bathrooms and shower enclosures.

Abstract: A novel gypsum board having antifungal properties is disclosed. The board comprises a gypsum core, front and back paper facings and an antifungal agent effective at inhibiting fungal growth. A preferred antifungal agent is cetyl pyridinium chloride. The antifungal agent can be present in the gypsum core and/or on one or both of the paper facings. In addition, the antifungal agent may be encapsulated in a material that releases the antifungal agent over time and/or upon exposure to moisture. Also disclosed are methods for preparing the aforementioned antifungal gypsum board.

Abstract: A gypsum wallboard that exhibits antimicrobial characteristics is disclosed. A method for making the wallboard is also disclosed. Suitable antimicrobial agents that may be applied to the wallboard or any components thereof include propiconazole, sodium pyrithione, tolyl diiodomethyl sulfone; tebuconazole; thiabendazole; 3-iodo-2-propynyl butylcarbamate; and mixtures thereof.

Abstract: A process for manufacturing plasterboard and a plasterboard manufacturing unit are provided, the process including feeding hydratable calcium sulphate and water into a first mixer (2) and into a second mixer (3); feeding in a facing (5); preparing a first gypsum slurry in the first mixer (2); preparing a second gypsum slurry in the second mixer (3); applying the first slurry onto the facing and forming a crude surface layer; applying the second slurry onto the crude surface layer and forming a crude core layer with a density lower than that of the crude surface layer; forming a plasterboard; hydrating and drying the board. This process allows the formation of the different layers of gypsum to be controlled independently.

Abstract: A cementitious veneer and laminate composition is provided. The cementitious laminate composition includes a substrate, a primer layer applied to the substrate, the primer layer comprising a mixture of polyvinyl alcohol catalyst, Portland cement, and sand; and a cementitious veneer layer applied to the primer layer, the veneer layer comprising a mixture of magnesium sulfate, filler, magnesium oxide, gypsum cement, and polyvinyl alcohol catalyst. The polyvinyl alcohol catalyst comprises a mixture of polyvinyl alcohol fibers dissolved in water and mixed with butylene carbonate. The veneer layer is applied to the substrate and primer layer by means including spraying and manual spreading. The veneer layer can be ornamentally manipulated either before or after curing of the veneer layer. The veneer composition can be formed into laminated tiles or panels for use in building applications.

Abstract: In some embodiments, alternate sources of aluminum or calcium are provided in various ways including the desired compounds. The further object of the present invention contemplate in situ creation of the compound in interest in fresh concrete and as a slurry which can be employed in remediation of existing concrete structures. A method of resisting corrosion in concrete containing metal elements is provided. It includes introducing into fresh concrete, containing metal elements, at least one compound capable of sequestering chloride ions. The method may also involve employing a compound which is capable of establishing a corrosion resistant oxide layer on the metal reinforcing elements. The invention also includes certain compounds which may be employed in the method as well as concrete structures containing the compounds.

Abstract: Process for the manufacture of plasterboards exhibiting a core density of less than 0.77 comprising the stages of the formation of a foam from water and a surfactant composed of at least one alkyl sulphate of formula H(CH2)nOSO3−M+, in which n is a number between 6 and 16, M is a monovalent cation and the mean number of carbon atoms nm is from 9 to 10, and the introduction of the foam obtained into a plaster slurry, characterized in that the amount of surfactant introduced does not exceed 0.32 g/l of plaster slurry.

Abstract: A gypsum-based composite structure is prepared from a slurry comprising a mixture of calcium sulfate hemihydrate, a cellulose ether additive other than CMC and an amount of water that is sufficient to form a slurry. The calcium sulfate hemihydrate is hydrated by the water forming a wallboard core reinforced by the cellulose ether additive. The concentration, viscosity grade and degree of substitution of the cellulose ether are selected to give the composite improved nail pull resistance and greater flexural strength.

Abstract: A reinforced wallboard core is prepared from a slurry comprising a mixture of &bgr;-calcium sulfate hemihydrate, a cellulose ether additive other than CMC and an amount of water that is sufficient to form a slurry and resulting in a wallboard density of less than 0.8 g/cc. The &bgr;-calcium sulfate hemihydrate is hydrated by the water forming a wallboard core reinforced by the cellulose ether additive. The cellulose ether, having a molecular weight of at least about 20,000 and a viscosity grade of at least about 100 cps, is selected to give the reinforced wallboard core improved nail pull resistance and greater flexural strength than unreinforced wallboard of the same density. The reinforced wallboard core may be used for reduced-paper wallboard and/or for lightweight wallboard, for example.

Abstract: A method enables gypsum/fiber board to be manufactured such that recessed areas are formed on the same face of the cut wallboard on all four edges without interrupting the production line. The system accommodates different lengths of cut wallboard as the lateral cut edge recess forming apparatus is adjustable in width to accommodate different lengths of cut wallboard.

Abstract: A composition used in making wallboard is provided. The composition requires at least fly ash, water and a first binder. The composition is located between two members that together form the wallboard. In one embodiment, at least the first binder is part of a foamable solution and part of a binder solution. In this embodiment, the fly ash, foamable solution and binder solution are combined in a mixer. The output of the mixer can be regulated based on detection of a magnitude related to viscosity of the composition. During the process for making the wallboard, the composition is sandwiched between the two members and subject to both preheating and subsequent heating stages. During the preheating, a sufficient number of bubbles associated with the binder are maintained in order to achieve a predetermined density based on the closed cells that are formed after the water evaporates.

Abstract: The invention provides a method of providing void spaces in gypsum wallboard and in a gypsum core composition such that the weight of the gypsum product is reduced without deleteriously affecting its mechanical properties. More specifically, the invention provides a method of providing void spaces in a gypsum wallboard comprising the step of adding air bubbles having different relative stabilities to a gypsum slurry, wherein the less stable air bubbles are sufficiently unstable such that they coalesce on contact with each other in the slurry to form larger air bubbles, and the weight ratio of the less stable air bubbles to the more stable air bubbles initially added to the slurry is such that there are a sufficient number of more stable air bubbles to prevent a majority of the less stable air bubbles from becoming large enough to rupture before the slurry sets sufficiently to prevent the slurry from filling void spaces left by ruptured bubbles.

Abstract: Compositions useful for the preparation of lightweight, high strength wallboards, and methods of making same are disclosed. The composition includes a slurry of calcium sulfate hemihydrate (stucco), water, starch, and a foam. The foam acts to provide large bubbles within the core slurry, thereby lightening the weight of the wallboard. The composition and method provide wallboards having lighter weights compared to standard wallboard, increased core strength, and increased paper-to-core bonding.

Abstract: Gypsum plaster compositions with improved adhesion to plastic surfaces and metal surfaces comprise from 10 to 90% by weight of gypsum plaster, based on the total weight of the composition, and also, where appropriate, other additives, and a combination of: a) one or more water-redispersible polymer powders based on one or more vinyl ester, (meth)acrylate, vinylaromatic, olefin, 1,3-diene, or vinyl halides monomers, and optionally other monomers copolymerizable therewith; and b) one or more alkali metal and/or alkaline earth metal salts of short-chain fatty acids having from 1 to 4 carbon atoms in the hydrocarbon skeleton and from 1 to 4 carboxy groups, and which contain no OH groups.

Abstract: An improved method and apparatus for imparting a smooth surface to gypsum fiber panels. The method involves imparting energy to the surface of a slurry as the slurry is dewatered just prior to rehydration. The apparatus used to impart the energy is a water spray including a source of pressurized water such as a pump, a distribution manifold and a plurality of nozzles to direct the water spray at the surface of the slurry. In operation, the water spray is directed against the surface of the slurry. The flow disrupts the slurry to a fraction of its total depth, thus dispersing clumps or flocs of commingled crystals and fibers in the depth that would give the surface of the finished panel a rough surface if they were allowed to remain.

Abstract: Paper and/or mat-faced gypsum board is prepared by applying a relatively thin coating of aqueous gypsum slurry containing a polyvinyl alcohol binder to one or two facer sheets. The polyvinyl alcohol binder provides adequate adhesion between the set gypsum core and the adjacent facer sheet(s) without the need for starch or other conventional binders. In one embodiment, polyvinyl alcohol is concentrated in one or more regions of the core adjacent to the facer sheet(s). In another embodiment, polyvinyl alcohol is applied to an aqueous gypsum slurry used to form the bulk core, such that the polyvinyl alcohol is present throughout the core.