Coating processes – Nonuniform coating – Edge or border coating
Reexamination Certificate
2001-08-28
2003-05-27
Parker, Fred J. (Department: 1762)
Coating processes
Nonuniform coating
Edge or border coating
C427S286000, C427S356000
Reexamination Certificate
active
06569497
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to drywall finishing, and more particularly to a method of reducing the time required to finish drywall joints and to a compound for sealing drywall joints.
The building industry widely uses gypsum board in the construction of residential homes, commercial buildings, and other structures. The gypsum board, also known as sheetrock or drywall is usually pre-cut in flat sheets of 4×8 or 4×12 foot, having a thickness of ½ or ⅝″. The sheets of the gypsum board are hung on wood or metal studs to form an interior wall of the building. Typical walls have joints between the sheetrock segments that must be covered to form a smooth surface for application of the wallpaper or paint.
A conventional method of finishing the drywall comprises a number of steps. First, a drywall joint compound is deposited along the joint as a thin bead. The drywall joint compound usually has limestone, water, mica, vinyl acetate polymer and may also have talc. The limestone may be substituted by dolomite or gypsum. If the compound comes as a dry powder, it is mixed with the necessary amount of water, stirred and then applied with a six-inch joint finishing knife to the joint. Immediately after that, a drywall tape is placed over the bead of the drywall joint compound and the joint finishing knife is run over the tape to press the tape and cause it to adhere to the compound.
The first coat of the compound with the tape is allowed to dry for 24 hours. Then a second coat of the joint compound is applied over the first coat to cover the tape completely and to cover the interface between the tape and the wall. The second coat is allowed to dry for 24 hours. Then a third coat is applied with a 10-inch joint finishing knife to make a wide strip of the joint compound on the wall that would entirely cover the tape as well as the first two coats. When the final coat dries, again for about 24 hours, it is sanded to remove imperfections and achieve a smooth finish. The dust is wiped off or blown off to make the wall ready for wallpaper or paint application.
The disadvantage of the conventional method is that it requires 3-4 days to finish one wall, with a 24-hour drying period between joint compound applications. The drywall finisher has to come back to the same job several times before the walls are finished. The time spent on finishing the walls directly translates into the cost of the building construction. It would be therefore a considerable advantage to provide a method that would reduce the labor time in finishing the drywall and thereby reduce the overall cost of construction.
The present invention contemplates provision of such a method and a novel compound for finishing a drywall that would reduce the curing time and eliminate the need for multiple joint compound applications.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method of finishing a drywall by eliminating the number of coats necessary to finish a drywall.
It is another object of the present invention to provide a drywall joint compound that has reduced curing time and is strong enough even with one application.
These and other objects of the present invention are achieved through the provision of a method of finishing a drywall, which includes the steps of mixing a drywall joint compound with a predetermined amount of water and a synthetic fiber, such as Columbian fiber. An optional liquid wallpaper adhesive may be added to the mixture. The mixed compound is then applied to the joint between the drywall sheets and allowed to dry for 24 hours. No further applications of the compound are necessary. The drywall joint becomes sealed with a smooth, strong seal.
The composition of the present invention contains between about 97.68% to about 98.8% of sheetrock compound, between about 0.247% to about 0.97% of water, between about 0.494% to about 0.73% of synthetic fiber, and between about 0.37% to about 0.61% by weight of the vinyl adhesive. The adhesive is selected from the family of vegetable adhesives
The presence of the synthetic fiber reduces the chance of the joint cracking, making the sealed joint somewhat “flexible.” At the same time, the joint seal is stable, capable of withstanding settling of the house, while preserving the even, smooth surface for the application of a wallpaper or paint. The same compound may be used for repairing the drywall and covering holes or punctures in the wall. The compound of the present invention eliminates the need for mesh fabric, which is conventionally used when repairing a drywall.
REFERENCES:
patent: 3891582 (1975-06-01), Desmaris
patent: 4039492 (1977-08-01), Hamilton
patent: 5079042 (1992-01-01), Frings
patent: 6238476 (2001-05-01), Sprinkle
patent: 6295794 (2001-10-01), Nordt et al.
DWC, LLC
Keaty Professional Law Corporation
Parker Fred J.
LandOfFree
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