Brushing – scrubbing – and general cleaning – Implements – Bladed spreader
Utility Patent
1999-07-14
2001-01-02
Spisich, Mark (Department: 1744)
Brushing, scrubbing, and general cleaning
Implements
Bladed spreader
C015S235600, C015S236080
Utility Patent
active
06167585
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method and a hand tool for plaster spreading and more specifically to serrated hand tools for spreading plaster and the like.
2. Description of the Prior Art
Construction practice have long required a reliable method and appropriate hand tool to spread plaster and other similar type compounds such as gypsum, cement, mortar, group, joint mixes, spackling pastes, etc. All of these and other similar compounds are described herein as “plaster” for the purposes of this specification.
For an experienced worker, spreading a plaster compound over a perfectly flat and well prepared surface does not present a challenge. It is when the surface is not flat as is encountered in most cases, when the presently known spreading methods need improvements.
In a commonly known plaster spreading technique, a hand tool or trowel with a straight edge is used to take some soft plaster from a container and apply it over the working surface trying to maintain a constant thickness of the layer of plaster. This thickness depends on the skill of the worker and the force with which the plaster is applied. However, when the surface has bumps or valleys, maintaining the constant depth becomes quite difficult. As a result, the final surface of the hardened compound is not perfectly flat. In order to improve this technique, it is known to apply the plaster in several steps, building up the plaster layers in a gradual way. This method requires a long time to complete because every consecutive layer of plaster has to cure at least 1 to 2 hours before the next one can be applied. Typically, at least three layers of plaster are applied this way to achieve a good result. Care should also be taken not to allow cracking of the plaster compound which may occur due to excessive and uneven thickness of the plaster layer. In addition, due to natural irregularities of this plaster application method, some hardened plaster has to be periodically removed to smooth out the surface which requires more working time. Finally, that and excessive thickness of plaster also lead to a higher consumption of plaster material and hence, higher material waste.
Serrated or notched trowels and hand tools are known in the prior art mostly for applying glue and tile compounds. They typically have a plurality of V-shaped or square notches along the working edge and are designed to evenly distribute the paste preparing the surface to be covered with tiles, linoleum and alike. Following examples illustrate some known serrated hand tools.
U.S. Pat. No. 2,287,231 by Cathcard is directed to a paste spreader for spreading paste, cement, glue and the like on a surface to be covered with a covering such as linoleum which evenly distributes the paste. The spreader blade is fabricated of a flexible material and is serrated along one edge.
U.S. Pat. No. 2,824,330 by Williams is directed to a spreader for cement and the like on a surface to be covered with a covering, such as Formica, which evenly spreads the cement. The spreader blade is square and is removably attached to a handle. Each of the four edges of the blade has different sized notches or serrations.
U.S. Pat. No. 3,916,472 by Carder is directed to a trowel for applying adhesives to a surface such as a floor or wall to be covered. The edges of the trowel are serrated to evenly spread the adhesive.
U.S. Pat. No. 4,316,302 by Clark is directed to an adhesive spreading trowel having all four edges either straight or serrated and is adapted for manufacture by injection molding.
U.S. Pat. No. 4,654,919 by Lieberman is directed to a spreader for applying plaster and cement to wallboard. The spreader has a spreader blade attached to a handle with a backing layer next to the blade to add rigidity to the blade. The edge of the blade extends past the edge of the backing layer. The plate is made of a flexible material such as plastic and has a straight edge as opposed to a serrated edge.
U.S. Pat. No. 4,804,321 by Riesgo is directed to a cement spreader with a blade having a plurality of squared notches.
U.S. Pat. No. 5,231,729 by Rose is directed to a tilers trowel having square notches and adjustment means for limiting the depth of material which can be applied.
U.S. Pat. No. 5,524,316 by Johnson is directed to a hand tool for spreading plaster on a substrate such as a ceiling and alike in decorative patterns. The tool has stiff but resilient serrated blade and a handle attached to the blade at an opposite or proximal edge from a serrated distal edge. Tool alignment marks are also provided to aid in decorative application of the plaster compound.
Finally, U.S. Pat. No. 5,778,482 by Sbrigato is directed to a serrated spreader for a cold-coat of roofing tar. It contains a hard rubber blade with serrations, which, when pushed over the surface to be roofed, spreads the desired coat of tar over a predetermined width of the surface to be roofed.
These and other known devices of the prior art fail to address the main problem of the plaster spreading work, namely allow for a quick to apply method of accurate plaster spreading over an imperfect surface without the need for multiple repetitive applications of plaster. Therefore, the need exists for a method and a hand tool to allow for such improvement in the plaster allying technique. In addition, the need exists for a plaster application method and a hand tool allowing for lower level of skill required to achieve smooth final surface, reducing the drying time between the layers, reducing the tendency of plaster to form cracks, and reducing the plaster material waste.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to overcome these and other drawbacks of the prior art by providing a novel method and a hand tool for plaster spreading using a serrated edge principle.
It is another object of the present invention to provide a method and a hand tool for plaster spreading allowing to substantially reduce the total time required to achieve the final smooth surface.
It is a further object of the present invention to provide a method and a hand tool for plaster spreading allowing to achieve a final smooth surface over somewhat irregular initial surface, all with lower level of worker skills.
Finally, it is another object of the invention to provide a method and a hand tool allowing plaster spreading with minimum waste of plaster material.
According to the method of the invention, a commonly known serrated edge principle is used in a novel way to aid in plaster spreading. After the surface is initially prepared to eliminate larger defects, the first step of a novel method includes applying a so called skim-coat of plaster using a serrated hand tool of a special novel design. Very little level of skill is required to apply a plurality of parallel plaster lines, the upper edges of which form a perfectly flat surface in spite of the irregularities of the underlying surface. It takes substantially less time for these lines to dry and harden as opposed to a regular generally thicker layer of solid plaster, in our experience about 20 to 30 minutes. Also, due to limited thickness of each individual plaster line, they almost never crack. The result of the first step is a plurality of parallel plaster lines having their upper edges defining the level plane of the final surface.
A second step of the novel method includes applying of a second coat of plaster over the dry plaster lines formed in the first step by filling the space between the lines with additional plaster using a regular hand tool or trowel with a straight edge. This step is also quite simple due to the fact that the hand tool edge slides along the hardened upper edges of the plaster lines formed in the first step so the surface is well defined and the final result does not depend on the level and consistency of force applied to the handle of the hand tool while spreading the plaster.
As a result of the first two steps, a smooth surface is formed over a layer of plaster of minimum thi
Fridman Emelian
Katz Mikhail
Leschinsky Boris
Spisich Mark
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