Method for applying plaster and cement to wallboard and the like

#The present invention is directed to a method for spreading plaster, cement, spackle, or the like, upon wallboard. In the finishing operations of wallboard, tape is usually applied between adjacent blocks of wallboard. Thereafter, plaster is spread over the tape and over adjacent portions of the adjoining wallboard blocks, to thereby fuse together the previously separate blocks of wallboard. Thereafter, in the usual fashion, plaster or the like is applied over the entire wallboard surface area to provide a finished product. The conventional tool for the application of the plaster over the tape adjoining adjacent wallboard portions has been a simple straight knife made of metal. In using this conventional knife in the application and spreading of the plaster, it has taken usually three or four separate and distinct spreading steps in order to correctly and smoothly place the plaster over the tape and adjoining wallboard portions. The multiple-step operation has been necessitated by the fact that the knife in current use must first be used to apply a large amount of the plaster on the wallboard portions, thereafter spreading it in an uneven fashion and, after that, smoothing it out which, by itself, takes usually two or more separate operations. Thus, the actual spreading of the plaster or the like over the tape, adjacent wallboard portions, and the rest of the wallboard portions, has been tedious, time consuming and a multiple-step operation.

#The very same knife that has been used to apply the plaster or the like to the tape and adjoining wall portions has also been used to apply spackle to fill in cracks in a wall before the painting of the surfaces. This also is a time consuming and multi-step operation, in the same manner as the above-described application of plaster to wallboard. In the application of the spackle to a crack, what is most important is to fill the crack with the spackle, and to thereafter insure that the wall portions adjacent on either side of the crack are made smooth. Using the conventional knife, this has been, as described above, a difficult task, since the application of the spackle is not done consistently and evenly over the crack and adjoining wall portions thereto.

#It is the main objective of the present invention to provide a method for spreading plaster, cement, and spackle to wall surfaces such that the amount of time required to do so is considerably shortened, the number of steps in order to accomplish the spreading is considerably reduced, and the final smoothing out thereof is made more even and smooth.

#The invention will be more readily understood with reference to the accompanying drawing, wherein:

#FIG. 1 is a top plan view of the spreader tool and in the method of the present invention;

#FIG. 2 is a side-elevational view taken along line 2--2 of FIG. 1;

#Referring now to the drawings in greater detail, the spreading tool for spreading plaster, and the like, on wallboard is indicated generally by Reference Numeral 10 in FIGS. 1 through 3. The tool shown in FIGS. 1 through 3 constitutes the first embodiment of the present invention. The tool 10 includes a handle portion 12 in the conventional manner by which a hand may grip the tool. The forward front portion 12' of the handle mounts a first supporting or backing layer 14 by which a tool application-surface layer 16 is given structural integrity. The rear portion 14' of the backing layer 14 is fixedly mounted within the front portion 12' of the handle 12, as clearly shown in FIG. 3. The backing layer 14 constitutes a first laminate of the blade structure of the present invention. The application-surface layer 16 is fixedly connected to the upper portion of the backing layer 14 by any conventional means, to thus form a two-layer laminate. The forward or front portion 16' of the application-surface layer 16 projects outwardly beyond the forward edge surface of the backing layer 14 as clearly shown in FIGS. 1 and 3. This forward projecting front portion 16' of the upper layer 16 constitutes the plaster, cement or spackle smoothing surface for applying same to a wallboard or the like. The application-surface layer 16 is made of a flexible plastic in the preferred embodiment, although a thin, flexible and appropriate metal may be used. For example, this application-surface layer may be made of 1/8th inch silicone rubber, or may be made of urethane.

#Each of the layers 14 and 16 is curved such that, when viewing FIG. 1, each layer 14 and 16 projects out of the plane of the page. For purposes of description, such curvature shall be termed concave, since it is being viewed from above the plane of FIG. 1. In FIG. 2, such curvature is clearly shown. The center of the curvature for each of the layers 14 and 16 is about a plane substantially dividing the handle portion 12 longitudinally thereof when viewing FIG. 1. Such plane projects perpendicularly to the surface shown in FIG. 1 and into the page thereof. While, for purposes of description, the curvature of the layers 14 and 16 has been described as concave, it is to be understood that such curvature need not be perfectly concave but may be meniscus-shaped or the equivalent thereof, so long as there is an offset from the central longitudinal portion of the application-surface layer as compared to the end tips thereof. This allows for the projecting edge surface portion 16' to be flexed inwardly upon sufficient pressure thereto via handle 12, so that the central longitudinal portion lies lie co-planal with the end tips thereof when applying the plaster or the like to the wallboard in order to spread it out evenly, to thus form a flat edge-surface. The midsection of the flexible layer 16 is indicated by Reference Numeral 20 in FIG. 2, while the midsection of the backing layer 14 is indicated by Reference Numeral 22 in FIG. 2. Thus, it is within the scope and purview of the present invention to provide a curvature of the layers 14 and 16 that are parabolic or other arcuate extension.

#When using the spreading tool of FIGS. 1 through 3, the plaster, or the like, is first emplaced upon the upwardly-facing surface of the application-surface layer 16, when viewing FIG. 3 which upwardly-facing surface is directed away from the layer 14. Thereafter, the upper surface of the layer 16 is placed against the wallboard at the portion thereof where the tape has been applied, or where the crack is located, and the handle is used to force in the central section of the projecting edge portion 16', so that the central portion thereof becomes co-planar with the tips of the layer 16 and coextensive therewith to form a flat, projecting surface. Thereafter, the tool is dragged along the wallboard surface, either vertically or horizontally or a combination thereof, with the application of sufficient pressure causing the edge portion 16' to force the plaster to fill in the crack or to cover the tape that had been applied, while simultaneously causing the plaster lying directly adjacent to the edge surface 16' to be forced to spread outwardly from the midsection of the layer 16, toward the tips, to cause it to be smooth and evenly distributed, all in one stroke. Thus, with just one stroke, the plaster is applied to the wallboard directly over a crack or tape, and simultaneously spread out on the plaster in an even and smooth manner. Thus, no additional applications or strokes of the tool are necessary to accomplish the application-spreading of the plaster at a crack or at a portion at which tape has been applied. The backing layer 14 is of sufficient stiffness and strength so as to prevent the flattening of the application-surface layer 16 other than at the edge surface 16' by which the plaster or the like is applied over the area to be worked and spread out smoothly therefrom. Regarding the curvature of the layers 14 and 16, such may take different forms as described above, with preferably the angle indicated by Reference Numeral 30 in FIG. 2 generally falling within the range of between 3 and 15 degrees, the angle 30 being subtended by the tangent to the midsection portion 22 of the layer 14 and a tangent to the outer tip portion of the same layer 14, as shown clearly in FIG. 2. The application-surface layer 16 is preferably made of a flexible polyurethane plastic, although other flexible materials may be used therefor, with the thickness thereof preferably being within the range of between 1/16th of an inch and 1/4th of an inch. Sufficiently flexible metal may also be used therefor. The backing layer 14 may be made of any hard, substantially non-flexible plastic or metal. Since the backing layer 14 provides structural integrity to the flexible layer 16, the flexible layer 16 need not, in and of itself, be fixedly connected to the handle portion 12 in the manner that the backing layer 14 is, although such may be done within the scope and purview of the present invention.