Abstract: An apparatus for texturing the surface of wet cast plastic acoustical composition during manufacture of acoustical tiles by use of spinning air rolls. In the apparatus, at least one hollow cylindrical roll that is perforated in a random manner is suspended over the surface of wet cast plastic acoustical composition, the roll being driven by a motor. The interior of the roll is preferably provided with a perforated air tube or pipeline, from which issues uniform air pressurization of the spinning roll vessel. By providing differential speed of the roll in contrast to the line speed of the wet plastic composition and different air pressurization of the roll, a wide variety of textures may be produced on the surface of the wet plastic acoustical composition.

Abstract: The invention concerns an improved method of calcining gypsum in which non-reactive hot gas is passed into contact with the gypsum from a source through a plurality of tubes extending downwardly into the gypsum. The invention also contemplates an improved apparatus which comprises a calcining kettle and a plurality of tubes connected to a common source of non-reactive hot gas and extending downwardly into the kettle and having openings in their lower regions to release the hot gas into the contents of the kettle. The invention provides a method and apparatus which produces gypsum plaster of improved quality and with less insoluble anhydrite.

Abstract: Gingivitis and related periodontal problems of the gingival tissues may be treated with a dental hygiene composition comprising an effective amount of a calcium sulfate compound such as calcium sulfate hemihydrate. Preferred compositions comprise mouthwashes and oral rinses containing about 5-90% by weight of calcium sulfate hemihydrate, a liquid carrier such as water, a humectant and an alcohol.

Abstract: A cement board having bare surfaces and a mesh of reinforcing fibers underlying the top, bottom, and longitudinal edge surfaces is made continuously on an improved apparatus which comprises a pair of edger rails which slidably rest on a conveyor belt and define the path of the cement board being made on the conveyor belt and a means for folding and pressing outer margins of the bottom mesh into the edge surfaces and the top surface.

Abstract: Hang-on furniture modules from various manufacturers differ in the placement of the hanger hooks extending from their back wall. A support cleat is frontally inserted in the unobstructed opening of a bifurcated, longitudinal channel at the edge of a stud in a partition. A longitudinal standard having a column of slots located to receive the hooks of a particular module is supported by the cleat as the standard straddles the stud in which the cleat is anchored.

Abstract: A storage stable water-based paint comprising a solid silicone resin and an ammonium salt of a drying oil modified acrylic copolymer provide a coating for barbecue grills and other appliances that are subjected to temperatures as high as 1300.degree. F. A smooth and continuous coating remains on the metal after burning off of the acrylic resin and firing of the metal at 1300.degree. F. The paint is redispersible and may be drawn down to 1.5 mils after storage at 120.degree. F. for more than 3 months when the pH is at least about 8.

Abstract: A paper particularly adapted for use as cover sheets in the production of gypsum wallboard, the paper having improved porosity and strength to permit better drainage and more rapid drying in the production of the paper to permit less fiber to be utilized, and to permit less heat to be utilized in drying the paper, providing for production of superior gypsum board. The paper comprises in weight percent:(A) fibers having a fiber freeness of from about 350 to 550 ml. Canadian Standard Freeness,(B) a buffering agent in an amount from about 0.25 to about 10%,(C) a neutral sizing agent in an effective amount to prevent water penetration, and(D) a cationic starch.In a preferred embodiment the paper is treated with a neutral internal sizing agent during its formation, and subsequently treated with a surface sizing agent after formation of the paper, in order to provide certain properties including better adhesion to the gypsum core.

Abstract: This invention relates to the manufacture of hydroxylapatite in a through-solution process wherein monobasic calcium phosphate is reacted with a calcium hydroxide solution. In a preferred embodiment, an acidic premix is formed by reacting phosphoric acid and calcium hydroxide with high shear agitation in a first stage, and thereafter reacting the acidic premix with a saturated solution of calcium hydroxide also under high shear agitation in a second stage. The second stage reaction is carried out in an alkaline solution by carefully metering the acid premix into the calcium hydroxide solution whereby the pH of the solution is maintained above 11 until the reaction is near completion. It is particularly preferred to use a stoichiometric portion of calcium hydroxide in carrying out the reactions. After the hydroxylapatite precipitate is recovered, it may be sintered at a temperature between about 700.degree. C. and 1100.degree. C. for about 5 to 30 minutes to form a crystalline hydroxylapatite.

Abstract: The unequal porosity and different textures of a drywall reinforced with joint tape and joint compound are concealed by a paint made from a low cost, easily dispersible powder in which the pigment volume concentration is about 70% to about 75%. A vinyl acetate/ethylene copolymer serves as the principle binder and a water soluble cellulose ether thickens the water dispersion of kaolin, attapulgus clay, mica, sodium potassium aluminum silicate and calcium carbonate.

Abstract: A tabular variety of acicular gypsum crystal filler is prepared by hydrating calcium sulfate dihydrate particles in a seeded continuously stirred reactor at a low level of super-saturation to obtain crystals having an aspect ratio of about 100:10:1 and average length in the longest dimension of about 100-450 micrometers. For the manufacture of paper, the obtained tabular crystal slurry may be directly added to the paper pulp before web formation to obtain a filled paper having high filler retention.

Abstract: The twisting of studs within the ceiling and floor rails of a partition is prevented by a quickly installable stud clip which may be moved along the rail to its desired position before being fastened to the rail and stud.The channel form top rail in this system has a pair of longitudinal slots just below the web which are defined by inwardly extending longitudinal tracks which are parallel to the web. The stud clip has a base plate from whose central portion a stud-engaging standard depends at a right angle. On the lateral portions of the plate there are skid elements which fit into the slots and engage the tracks. Extending from one lateral portion of the plate beyond the plane of the standard is a relatively narrow locking tab which is in edgewise abutment with a track. The abutment of the locking tab with the track prevents rotation of the stud clip within the rail.

Abstract: Apparatus and method for belt transfer printing of nonflat surfaces of porous articles wherein the printing of the article by a first region of the belt is carried out substantially simultaneously with the inking of a second region of the belt. In a preferred embodiment, the apparatus comprises an endless belt with a screen printing device disposed along a first run of the belt and a vacuum workpiece support box disposed along a second run of the belt with an opposed sealing frame. A workpiece is loaded in the vacuum box, a vacuum is created through the workpiece to draw a pattern carrying region into printing contact with the workpiece surface while another pattern is being inked onto a second region of the belt. The workpiece is replaced with a second workpiece and the second region of the belt is advanced into registration with the second workpiece.

Abstract: A shower door mounted on rails for movement thereon and having a lower guide assembly which is free-floating and which comprises a flange retained in a lower sill track slot and having the other end hingedly mounted on a flange of the shower door.

Abstract: An oil well drilling fluid containing mineral fibers which have been coated individually with a dispersant is better able to plug voids and fractures in the rock being drilled than those of the prior art because the mineral fibers are thoroughly dispersed. The fluid is substantially free of nodulated fibers. A dispersant such as a polyethoxylated quaternary ammonium salt is added to a stream of air which attenuates streams of molten slag into fibers. The fibers are uniformly coated with the dispersant and nodules thereof uravel easily when placed in a drilling fluid.

Abstract: A drywall furring system comprises a plurality of longitudinal carrying channels having congruent tongues co-planar with, spaced apart along and depending from the opposite flanges of the channels and a plurality of furring channels having pairs of slots spaced apart along the opposite flanges thereof. On opposite edges of the tongues there are tabs tapering upwardly from the rounded corners thereof and elongated, narrow fingers whose lower margins angle up from a point space apart from the distal edges of the tongues. The tabs and fingers have seats in the same horizontal plane and the fingers have retaining hooks extending up beyond the seats. A gridwork of the carrying channels and furring channels is constructed by aligning opposed congruent fingers of the former with a pair of slots in the latter and passing the fingers through the slots and pushing the opposite flanges of the furring channel over the rounded corners of the tongues so that the furring strips rest on the seats of the fingers and tabs.