GB2615420A

GB2615420A - Improvements relating to trowels

Info

Publication number: GB2615420A
Application number: GB2303603.1A
Authority: GB
Inventors: Robert Walton Gray Peter
Original assignee: Refina Ltd
Current assignee: Refina Ltd
Priority date: 2020-10-15
Filing date: 2020-10-15
Publication date: 2023-08-09
Also published as: GB202303603D0; GB2599938B; GB202016382D0; GB2599938A

Abstract

A plastering trowel 1 for flattening and smoothing finish plasters, the trowel comprising a blade 5 constructed from a flexible sheet material, a central spine 4 for stiffening the trowel and a handle 2 connecting via the spine to a central region of the blade. The blade defines a pair of peripheral ends 10, 11, the thickness of the blade tapering from the central region to the ends. The blade is machined during manufacture. The blade may have friction-reducing indentations 12 defined in the working face of the blade which may be pits of grooves oriented parallel to one another, with a depth of less than 1mm. Further disclosed is the blade of the trowel, and a method of manufacturing the blade comprising reducing the thickness of the blade at the ends and forming the indentations.

Description

Improvements relating to trowels

Field of the invention

The present invention relates to a trowel for use in applying and finishing coatings onto internal and external floors, walls and ceilings. The present invention relates in particular to a plastering trowel for applying and smoothing finish plasters.

Background to the invention

A plastering trowel is a common tool used by skilled plasterers for the application of plaster, and similar coatings, to building surfaces. Plastering is a skill that can take many years to develop to an acceptable standard, and part of this challenge resides in a plasterer being able to dynamically control the movement, angle and pressure of the trowel blade to achieve the desired finish. This is especially the case for achieving a smooth flat surface for interior walls and ceilings, typically via the application of a finish plaster.

For this, a plastering trowel is often used. This has certain characteristics that differentiate it from other trowels, such as those used for concreting. Plastering trowel blades generally have a thin (typically between 0.3mm-0.7mm) rectangular blade with a handle orientated parallel to the plane of the blade. Furthermore, the blade of a plastering trowel is typically constructed from a rust-resistant metal, such as stainless steel. This allows the blade to be thin, but resilient enough to be laterally flexible during handling without warping. This ensures that the blade can conform to the surface being worked allowing a plasterer to apply an even pressure to form a smooth surface.

A stainless steel blade also is able to become desirably "worn-in", with the long peripheral ends of the blade being abraded through use, and so sharper. At the same time, the corners of blade become more rounded. These changes, caused by wear, allow smoother finishes to be obtained. However, one issue is that it can take time for the blade to become worn-in gradually over time. Some plasterers choose to intentionally wear down these ends, for example using sandpaper to sharpen them practically to an edge. However, this does not necessarily lead to a reliable wear profile, and is inconvenient.

Another problem that can arise during the flattening and smoothing of plaster is unwanted adhesion and suction between the blade and the plaster, potentially pulling plaster away from the underlying surface or causing tearing of the plaster. Naturally, this can be offset to some degree by handling the tool with greater skill and dexterity, but this can slow down the process of finish plastering.

It is against this background that the present invention has been devised. Summary of the invention According to a first aspect of the present invention there is provided a trowel. The trowel may be suitable for applying and/or smoothing various coating materials, such as plasters, cements, renders and adhesives. The trowel may be a skimming trowel.

Preferably, the trowel is a plastering trowel. Preferably, the trowel comprises at least one of a handle, a blade, an elongate central spine and a bridge. Preferably, the blade is constructed from an integral piece of sheet material. Preferably, the blade is constructed from a thin sheet of metal, ideally a rust-resistant metal such as stainless-steel.

Preferably, the blade is broadly rectangular in shape, with a pair of parallel lateral long peripheral ends, and a pair of short peripheral ends at a front and rear of the blade. The blade, although generally rectangular in shape, may however define slightly rounded corners.

Preferably, the blade defines a working face for applying and working plaster in use. Preferably, the blade further comprises a handle face, reverse to the working face, to which, in turn, the spine, the bridge, and the handle are attached. Specifically, the spine may be attached to a central region of the blade, extending longitudinally, ideally parallel to the pair of long peripheral ends. Advantageously, this stiffens the trowel longitudinally, without sacrificing lateral flexibility. The bridge extends between and connects the spine and the handle, and is ideally integrally formed with the spine. The bridge extends away from the handle face and spine, thereby leaving a gap between the handle and the blade of the trowel to accommodate the hand of a plasterer. The handle is oriented approximately parallel to the plane of the blade. It should be noted that the bridge preferably defines a single connection point between the handle and the spine. This enhances the flex response of the blade beneath the handle, and also makes the trowel easier to turn and otherwise manipulate.

Drag-reducing indentation are defined on the working face of the blade, such as grooves or pits. Preferably, indentations are formed by machining (e.g. milling) the working face of the blade during manufacture. Preferably, grooves are between 50-500 microns in depth.

Indentations such as pits may be formed by the chemical treatment of the working face of the blade -for example, via chemical burn.

Advantageously, such indentation can improve the ability of the trowel to retain plaster on the working surface, and also reduce drag in use of the trowel. This can minimise the chance of plaster being pulled away unintentionally from a surface being worked, and also can speed up the application of a smooth coat of plaster. Another advantage is that the indentations can provide a more even dynamic distribution of plaster in use.

Preferably, the thickness of the blade tapers inwardly between a centre of the blade, to each long peripheral end of the blade. For example, the thickness may taper in from -0.6mm in the centre to -0.4mm at these long peripheral ends.

The thickness of the blade at the centre may be between 0.3mm and 1.5mm. More preferably, the thickness of the blade at the centre is between 0.3mm and 0.7mm. Moreover, the thickness of a long peripheral end may be between 20% to 80% of the thickness of the blade at the centre. Preferably, the blade tapers so that its working face is slightly convex, at least in part.

Preferably, the thickness of the blade is controlled during manufacture, for example by machining (e.g. milling or grinding) the working face of the blade in the region of the long peripheral ends. Advantageously, it is possible to manufacture the blade of the trowel in this way from an otherwise planar sheet material of uniform thickness.

During manufacturing, the indentations may be formed in the working face of the blade after controlling the thickness of the blade. Advantageously, this means that the trowel need not be intentionally worn-in -which may otherwise reduce the effectiveness and drag-reducing advantages of the indentations.

According to a second aspect of the present invention there is provided a method of manufacturing a trowel, or a blade of a trowel, the method comprising at least one of the steps of: providing a planar sheet material in the shape of the blade of the trowel, reducing the thickness of the material in the region of its peripheral ends and forming indentations on a working face of the blade of the trowel. The step of reducing the thickness of the material may be performed prior to the step of forming indentations on the working face of the blade.

It will be understood that features and advantages of various aspects of the invention may be combined or substituted where context allows. For example, the features of the trowel of the first aspect of the invention may be provided as part of the manufacturing steps of the method according to the second aspect of the present invention. Furthermore, individual features in isolation, such as the blade of the trowel of the first aspect of the invention may themselves constitute further aspects of the present invention.

Brief description of the drawings

In order for the invention to be more readily understood, embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic perspective underside view of a trowel according to a first embodiment of the present invention; Figure 2 is a front view of the trowel of Figure 1; Figure 3 is an enlarged partial view of the trowel of Figure 2; Figure 4 is an underside view of the trowel of Figure 1; Figure 5 is an underside view of a trowel according to a second embodiment of the present invention; Figure 6 is an underside view of a trowel according to a third embodiment of the present invention; Figure 7 is an underside view of a trowel according to a fourth embodiment of the present invention; Figure 8 is an underside view of a trowel according to a fifth embodiment of the present invention; Figure 9 is an underside view of a trowel according to a sixth embodiment of the present invention; and Figure 10 is an underside view of a trowel according to a seventh embodiment of the present invention;

Specific description

Figure 1 is a schematic perspective underside view of a plastering trowel 1 according to a first embodiment of the present invention. The trowel 1 comprises a handle 2, a bridge 3, a spine 4 (shown in dotted outline), and a blade 5.

The blade 5 is constructed from an integral piece of stainless steel sheet material, having a planar rectangular handle face 6, and a rectangular working face 7 reverse to the handle face 6. Axially, at its front and rear respectively, the blade 5 defines a pair of short peripheral ends 8, 9 of equal length and parallel to one another.

Figure 2 is a front view of the trowel 1, and Figure 3 is an enlarged partial view of the trowel of Figure 2 in which the front short peripheral end 8 can be more clearly seen.

Referring back to Figure 1, laterally, at its left and right side respectively, the blade 5 has a pair of long peripheral ends 10, 11, parallel and of equal length to one another, and perpendicular to the short peripheral ends 8, 9. Although not discernible in Figure 1, the corners of the blade 5, where short and long ends meet, are rounded slightly.

The blade has a central longitudinal axis X which extends parallel to and is equidistant from each long peripheral end 10, 11. A central vertical plane passing through the axis X, and perpendicular to a plane along which the blade 5 generally extends, bisects the trowel 1 as a whole into two equal halves.

The spine 4 is affixed to the handle face 6 of blade 5 adjacent to the axis X, and is elongate in the orientation of the axis X over a majority of the axial length of the blade 5.

The connection between the spine 4 and the blade 5 is achieved via stud welding and press-fitting the two together, but alternative fixing methods, such as spot-welding, riveting and sticking via adhesive, may be used instead or in combination in alternative embodiments.

The spine 4 is integrally-moulded with the bridge 3 which rises from the spine 4 from a single position. The bridge 3 initially rises vertically away from the blade 5 and then curves around to a substantially horizontal orientation to transition into the handle 2 of the trowel 1. Specifically, the bridge 3 defines an integrally-formed tang over which a handle 2 is fitted as a sleeve during manufacture or assembly of the trowel 1.

The handle 2 is constructed from rubber and contoured to facilitate reliable gripping of the trowel 1 by a plasterer. In alternatives embodiments, the handle may be constructed from wood, resilient plastics material or other suitable materials, including cork and leather, at least in part. The bridge 3 extends away from the handle face 6 and spine 4 enough to leave a gap to accommodate the hand of a plasterer.

The handle 2 is positioned vertically-above the blade 5 at a relative central location both axially and laterally. Furthermore, as the components of the trowel 1, including the handle 2, bridge 3, spine 4, and blade 5 lie within and are equally bisected by the central vertical plane, the trowel is balanced, and so easier to manipulate in use.

Figure 4 is an underside view of the trowel 1 of Figure 1, and the rectangular working face 7 of the blade 5 in particular. A series of parallel diagonal grooves 12 are defined in the working face 7 of the blade, the grooves being spaced at equal intervals from one another.

In alternative embodiments of the trowel, as shown in Figure 5 to 10, different indentations may be provided on the blade 5a, 5b, Sc, 5d, 5e, 5f. These may be in the form of grooves 12a, 12b, 12c-as shown in Figures 5,6 and 7, or pits 12d, 12e, 12f as shown in Figures 8, 9 and 10 respectively. These are exemplary variations of, for example differently-shaped grooves, with varying depths, spacings and patterns.

It should also be noted that in other embodiments, the trowel may not necessarily have a rectangular working face 7 -trapezoidal or diamond-shaped trowels may be provided instead, for example.

Referring back to Figure 3, the thickness of the blade 5 is not uniform. Rather, it tapers inwardly in the lateral direction from the centre of the blade 5 (i.6. adjacent to the spine 4 and central longitudinal axis X) toward each long peripheral end 10, 11 of the blade 5. In the present embodiment, the thickness of the blade 5 in the central is approximately 0.6mm, and the thickness at each long peripheral end 10, 11 is approximately 0.4mm.

In alternatives, different thickness may be used depending on the material used for the blade 5, its overall size, and degree of flex required. In the current embodiment, the taper starts from the centre, with the thickness reducing consistently towards each long peripheral end 10, 11. In alternative embodiments, the taper may begin between the centre and an end 10, 11, and/or the angle of taper may vary along the lateral width of the blade 5.

The blade 5 is tapered such that its handle face 6 remains substantially planar, and the working face 7 is slightly convex. This is achieved by grinding the working face 7 of the blade 5 in manufacture. Advantageously, it is possible to manufacture the blade of the trowel in this way from an otherwise planar sheet material of uniform thickness.

Referring back to Figure 4, during manufacturing, after the working face 7 of the blade 5 had been milled to reduce the thickness of the blade in the region of the lateral peripheral ends 10, 11, the working face 7 can also be milled to define the series of diagonal grooves 12. As the latter requires a more intricate milling operation, it is preferably performed afterwards. However, in alternatives, it is possible to reverse the order of these steps, or even carry them out simultaneously, providing a sufficiently sophisticated milling and/or grinding machine is available.

Each groove 12 is approximately 100 microns in depth and width, having a V-shape profile. In alternative embodiments, the depth and width of grooves need not be the same, and may range between 1-5000 microns. In alternatives, the preferred depth of the grooves is between 50 to 500 microns. The preferred width of the groove can vary significantly, but generally ranges from 50 to 5000 microns.

Additionally, the profile of the grooves may be rectangular or rounded. Furthermore, in alternatives, the spacing between each groove may not necessarily be regular.

Generally, however, parallel grooves are desirable, as this regularises the drag response of the trowel in use.

Also, in alternative embodiments, it is possible to establish grooves or other indentations in the working surface of the blade via other means. For example, it may be possible to use alternative machining means, laser-cutting, chemical-etching, etc. Chemical etching is particularly suitable for the formation of pits in the surface of the working face of the trowel, as show in Figures 8, 9 and 10.

Advantageously, indentation such as pits and grooves can improve the ability of the trowel to retain plaster on the working surface, and also reduce drag of the trowel, in use. This combined with the sharper lateral ends of the trowel 1, which enhance the flex response of the trowel 1, allow a smoother finish to be achieved by a plasterer.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the scope of the appended claims.

The following labelled statements set out further aspects of the present invention: Al. A plastering trowel, suitable for flattening and smoothing finish plasters, the trowel comprising a blade constructed from a flexible sheet material, a central spine for stiffening the trowel longitudinally, and a handle, the handle connecting via the central spine to a central region of the blade; wherein: the blade defines a pair of peripheral ends either side of and spaced from the spine, the thickness of the blade adjacent to the pair of peripheral ends being less than the thickness of the blade within the central region of the blade; and drag-reducing indentations are defined within a working face of the blade.

A2. The trowel of clause Al, wherein the working face of the blade is convex, at least in part.

A3. The trowel of any preceding clause, wherein the indentations have a depth of less than lmm.

A4. The trowel of any preceding clause, wherein the indentations comprise a series of grooves, oriented parallel to one another.

A5. The trowel of any preceding clause, wherein the indentations comprise pits.

A6. The trowel of any preceding clause, wherein the thickness of the blade adjacent to the pair of peripheral ends is less than 80% of the thickness of that of the central region of the blade.

A7. A blade of the trowel according to any preceding clause.

A8. A method of manufacturing a blade of a trowel according to clause A7, or a trowel according to any one of clause Al to A6, the method comprising: providing a planar sheet material in the shape of the blade of the trowel; reducing the thickness of the material in the region of its peripheral ends; and forming indentations on a working face of the blade of the trowel.

Claims

CLAIMS1 A plastering trowel, suitable for flattening and smoothing finish plasters, the trowel comprising: a blade, a central spine for stiffening the trowel longitudinally, a handle, and a bridge that extends between and connects the spine and the handle; wherein: the handle connects via the bridge and the central spine to a central region of the blade; the bridge defines a single connection point between the handle and the spine the blade defines a pair of peripheral ends either side of and spaced from the spine; the blade is constructed from a flexible integral piece of sheet metal material; and at least one of a working face and the pair of peripheral ends of the blade are machined during manufacture of the plastering trowel.
2. The trowel of claim 1, wherein the spine is integrally-moulded with the bridge.
3. The trowel of claim 1 or claim 2, wherein the working face of the blade is convex, at least in part.
4 The trowel of any preceding claim, wherein the thickness of the blade adjacent to the pair of peripheral ends is less than the thickness of the blade within the central region of the blade.
5. The trowel of any preceding claim, wherein drag-reducing indentations are defined within a working face of the blade.
6 The trowel of claim 5, wherein the indentations: have a depth of less than 1mm; comprise a series of grooves, oriented parallel to one another; and/or comprise pits.
7 The trowel of any preceding claim, wherein the thickness of the blade adjacent to the pair of peripheral ends is less than 80% of the thickness of that of the central region of the blade.
8. A blade of the trowel according to any preceding claim.
9. A method of manufacturing a blade of a trowel according to claim 8, or a trowel according to any one of claims 1 to 7, the method comprising: providing a planar sheet material in the shape of the blade of the trowel; and machining at least one of a working face of the blade, and the pair of peripheral ends.