Brushing – scrubbing – and general cleaning – Implements – Mason's trowel or float
Reexamination Certificate
1999-01-08
2001-06-05
Chin, Randall E. (Department: 1744)
Brushing, scrubbing, and general cleaning
Implements
Mason's trowel or float
C015S236070, C015S235400, C015S245100, C425S458000
Reexamination Certificate
active
06240591
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally concerns drywall finishing tools.
The present invention particularly concerns a drywall finishing tool directed to the manipulation of drywall compound in selected wall joints that are formed from and by drywall panels abutting at a particular range of angles.
2. Description of the Prior Art
2.1 General Drywall Finishing
The tool of the present invention can be sufficiently understood without having much understanding of, nor appreciation for, the drywall finishing process. However, a good hand tool is not merely operative in a process, but facilitates, or even dictates—hopefully in a new and improved manner—the performance of the process. Accordingly, some understanding of the drywall finishing process is not adverse to appreciation of the tool of the present invention.
The finishing of drywall is sometimes called taping, or even spackling. As well as shaping tools like that of the present invention, a compound pan and 5″, 8″, and 10″ drywall knives are generally used. Some drywall finishers prefer a 6-in. tool for applying the first coat of compound, followed with a 10-in. tool for the second coat and a 12-in. blade for the final skim coat. Generally speaking, wider knives are harder to control. All tool blades are desirably flexible, and the tool of the present invention will also be seen to be flexible.
Selection of compound is important. Compound is available in two types. One is called a setting compound that hardens by a chemical reaction. The other is a drying compound that cures by evaporation. The latter is available in powder or a ready-mix version, but for most people the ready-mix version is much more convenient. A typical compound suitable for use with existing tools and with the tool of the present invention is the relatively new ready-mix drying compound called Lightweight Plus 3 available from United States Gypsum (USG). It reportedly shrinks less, weighs less and is easier to sand than the company's standard drying compound, without sacrificing any strength.
Joint tape may be either paper tape or a self-sticking fiberglass mesh tape. The great advantage of the fiberglass tape is that it eliminates the need for the first coat of compound—and that's a major saving in labor. But tape manufacturers say the fiberglass product should be used only with setting compounds, not drying ones. In the opinion of many professionals the difficulties of working with a setting compound outweigh the advantage of using the fiberglass tape.
There are various approaches to the finishing process. However, a few rules of thumb are always approprialean as possible.
This means wiping off the excess compound on the edge of the pan after each pass with the tool. Second, dried compound is never mixed into fresh compound. Even the smallest piece of dried debris will leave a messy gouge in the finished surface. If dried compound finds its way into a pan or pail, it must be removed immediately. Finally, the surface of the compound will be only as smooth as the stroke you use to apply it. (The tool of the present invention will be seen to excel in supporting smooth and even stroking of drywall compound.) In the beginning, an inexperienced finisher should make a concerted effort to lengthen his/her strokes and keep the tool aligned with the direction of the joint. Until a finisher accrues experience and gets the knack, compound may squeeze off the tool and fall to the floor. But by loading the tool with less compound, the finisher can usually minimize the mess.
Joint sequence usually begins with the butt joints—those on the ends of the boards—followed by tapered joints—those along the edges—followed by inside corners and then outside corners. (The tool of the present invention will be seen to be applicable to both inside and outside corners.) With normal straight-edge tools inside corners normally have to be done in two steps because it is only possible to work on one side of the joint at a time. If any attempt is made to finish both sides at once, a conventional straight-edge tool will foul the first side while work is attempted on the second side. (The tool of the present invention, like some few others in the prior art, will be seen to advantageously permit finishing both sides of an inside corner at one time.)
2.2 Finishing of Butt and Tapered Joints
Although the finishing of butt and tapered joints will be seen to be substantially irrelevant to the preferred use of the tool of the present invention, the conventional manner of finishing these joints will be discussed in a few paragraphs within this BACKGROUND OF THE INVENTION section for ease of later comparison to the preferred techniques, and steps, for using the tool of the present invention. Drywall finishing work begins by mixing of joint compound, sometimes called mud. Although mixing isn't absolutely necessary with ready-mix compounds, to do so smooths out the compound and makes it easier to apply. Starting at a butt joint, the finisher loads up a 5-in. tool, making sure that its corners are clean, and applies the compound starting at one end of the joint. Application proceeds as smoothly as possible, the tool being reloaded when depleted of compound. The cleaning of the tool on the side of the pan and the smoothing of the entire joint preferably transpires in one stroke.
The tool is not pressed so hard that all of the compound is removed. If the surface is scraped clean in an area, compound must be re-applied because the paper tape won't stick to the paper covering on the drywall without compound underneath. Once the compound is smooth, a piece of joint tape is cut to length and embed in the compound by use of the fingers. The middle of the paper is aligned directly over the middle of the butt joint.
The tape is smoothed into the compound with a 5-in. tool, any excess that squeezes out being wiped off. The goal is to get enough compound on the wall to hold the tape, but not so much as to leave a noticeable bump. After practice a finisher is able to get a relatively smooth surface with the tape straight and flat.
Once the tape is in place, the entire joint is covered with more compound, this time using an 8-in. tool. The same techniques are employed as described for the 5-in. tool.
One of the most difficult joints is a ceiling butt joint. In the first place, the finisher is working over his or her head, which is always awkward. And in the second, a butt joint has no tapered edges that tend to hold compound better. To start such a joint, the tool is loaded as before and pressed against the ceiling. The tool is then slowly moved across the joint in a smooth stroke while being progressively flattened during the course of movement. This motion helps reduce falling compound while at the same time yielding a smoother surface. This movement is difficult for beginners, but, with practice, mess can be held to a minimum.
Tapered joints are easier to finish because of the depression built into the long edges of all drywall panels. They are nonetheless approached just like the butt joints. First, the joint is filled the joint with compound using a 5-in. tool. Then, the tape is embedded by use of the fingers, and smoothed into place with the 5-in. tool. Finally, the first coat is finished by applying compound with an 8-in. tool. When doing flatwork, as the butt and tapered joints are sometimes called, it makes sense to cover all screw and/or nailheads, too. Joint compound is simply over each of them, with any excess scraped off.
2.3 Corner Joints
Corner joints, both inside and outside, will be seen to be most similar to certain other particular joints that are the province of the tool of the present invention. As mentioned ear except the first—of the finishing process has to be done in two steps, to allow drying time in between. Although this seems inconvenient, sensible planning permits organizing work in a way that incorporates the needed drying time.
To start an inside joint, a 5-in. tool is first loaded on one corner
Chin Randall E.
Fuess & Davidenas
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