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Patent Searching and Data

Document Type and Number:
WIPO Patent Application WO/1988/006418
Kind Code:
A paintbrush in which the painting head is constructed from a number of pre-cut and glued bundles of drawn glass or quartz fibres. These bundles are prepared from a bulk reel of glass roving utilising an apparatus which automatically and continuously applies glue to and cuts the roving at desired intervals. These bundles may then either be combined using conventional techniques for paintbrush manufacture, or may be combined to construct a novel brush which may be cut back when worn to expose a new brush of smaller cross sectional area.

Application Number:
Publication Date:
September 07, 1988
Filing Date:
February 25, 1988
Export Citation:
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International Classes:
A46D1/00; (IPC1-7): A46D1/00
Foreign References:
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1. A paintbrush comprising a handle, means for attaching a fibrous painting head to that handle, and a painting head made up of fibres of finely drawn glass.
2. A paintbrush according to claim 1 in which the painting head is constructed from pre cut and bonded elements or brushlets rather than from a bundle of separate fibres.
3. A paintbrush according to claim 2 in which a ring of brushlets of finely drawn glass surround on a core of more coarsely drawn fibre brushlets.
4. A paintbrush according to claims 2 and 3 in which brushlets comprising fibres of drawn quartz are substituted for some or all of the glass brushlets.
5. A paintbrush according to claims 14 in which a proportion of the brushlets are sufficiently long to form the core of a handle which may be made desirably stiff by the application of a coating of resinous or plastics materia1 s .
6. A paintbrush according to claims 15 in which two or more lengths of brushlet are combined and partly covered with strengthening sleeve which may be cut back to one or more alternative positions to reveal a smaller cross sectional area than the original.
7. An apparatus capable of automatically and continuously making glass fibre brushlets from a bulk reel of fibreglass tape or roving which consists of many separate parallel fibres.
8. An apparatus according to claim 7 comprising means for curing that glue and means for cutting the glued roving at desired intervals. SUBSTITUTE SHEET .
9. A paintbrush, a method of making a paintbrush, or an apparatus, substantially as hereinbefore described with reference to and as illustrated by any single figure or group of figures of the accompanying diagrammatic drawings.
10. A paintbrush, a method of making a paintbrush, or an apparatus, comprising any operable combination of relevant features disclosed in this specification, other than as claimed in any of the preceding claims.*& 000.

This invention relates to the materials used in and method of manufacture of an improved paintbrush.

The process of painting may be described as the application of a liquid or gel, usually containing fine particles of a solid colouring matter, to a solid surface for the purposes of colouring and/or protecting that surface.

Liquid or gel paints can be sprayed, applied by a roller or sponge pad, but in many cases are applied by a brush. A typical task is the application of white gloss paint to household woodwork, when some common problems arise as fol lows :

1) Brush marks left on the painted surface.

2) Difficulty in creating a clean edge line along the boundary of the painted surface.

3) Fibres becoming detached from the brush due to imperfect gluing or breakage, which then attach themselves to the painted surface.

4) Difficulty in cleaning the brush after use, particularly with oil based paints.

5) The fibres rapidly wear, making the brush unusable,

Animal hair, typically pig bristle, is the normal material for making a brush, when scales on the hairs hold paint and the natural stiffness allows correct pressure to be applied over a wide range of brush sizes. Nylon fibres have also been used, when the ends are usually frayed out to compensate for the fact that these have parallel rather than tapered ends as is the case with animal hairs.

The stiffness of these fibres, be they animal or synthetic,


does give rise to brush marks unless used by an expert, and the scales on, or induced fraying of the fibres, trap paint making it difficult to wash out.

The relatively stiff fibres, under the pressure applied when painting, tend to separate out at the edges of the brush away from the main body of the fibres giving uneven application of paint, and therefore a ragged edge line.

Flat sided rather than round brushes of one half inch width or more are usually not solid fibre packs, but have a flat wedge inserted into the ferrule which holds the fibres in place. The purpose of this wedge is to reduce the number of fibres in a brush of given cross section and width, and to therefore reduce the otherwise excessive volume of paint which the brush would carry. Several time consuming operations are required to make the ferrule, insert the fibres, glue and wedge them in place, make a handle, then rivet or glue the ferrule to the handle.

According to the present invention there is provided a paintbrush having fibres of finely drawn glass or quartz instead of the aforementioned animal or nylon fibres.

The use of these fibres has been found to give several advantages both in performance if employed using the afore¬ mentioned traditional method of construction, and in improved paintbrush manufacturing techniques which can be applied if these fibres are used.

The fibres can be drawn to a wide range of diameters from 10 microns upwards, and the correct fibre, or combination of fibres chosen to give the desired stiffness or "feel" to a brush of any given size and fibre length.

It has been found that:

1) These very fine fibres leave no visible tracks in paint and thus no brush marks.

2) The edge fibres, due to surface tension effects, tend to remain bonded to. the main body of fibres creating a far smoother and controllable edge line.

3) Any fibres that do break or become detached and adhere to the painted surface are invisible due to their fine diameter and transparency.

4) The very smooth fibres do not trap paint, enabling even oil or bitumen based paints to be washed out with soap and water.

5) The hard glass or quartz fibres have a far longer wear life than animal hair, and even when they do wear, the important tip cross section remains the same.

A finished brush made with these fibres has a very soft and bushy appearance and feel, and on first examination appears unsuitable for accurate painting. Surprisingly, when the brush is dipped into paint, surface tension effects change the whole appearance and feel. The brush becomes far more compact and stiffer, looking and feeling like a normal paintbrush.

Figure 1 shows in end view the cross section of a typical flat paintbrush utilising fine glass and/or quartz fibres. For example only, two types of fibres are used, the fibres in area B are finer than, and surround stiffer ones in area C, which provide the extra stiffness which may be required in larger brushes. The ferrule A holds the fibres in position and a wedge D reduces the total cross section of the fibre bundle if this is found to be desirable in larger brushes. Although for many applications a solid bundle of fine fibres of identical diameter may be used, figure 1 shows how prior art manufacturing techniques can be used to easily make a large brush with the correct amount of stiffness, but which can still give a smooth painted surface free of brush marks.


Because the fine glass or quartz fibres are continuously drawn, they are commonly produced in the form of a loose- tape known as a roving. These rovings have a cross section of between three and five square millimetres and contain thousands of separate parallel fibres, each with a length between 1,000 and 10,000 metres.

An improved method of brush manufacture, according to the present invention Is now described with reference to figure 2 in which a continuous roving E passes between the synchronous wheels F and G on which at convenient spaces are mounted projections H which are shown in cross section in figure 3 and have a shallow recess cut in the direction of rotation of the wheels. The projections H pass through a shallow tray I filled with resin (or plastics) based glue so that on rotation of the wheels the roving is intermittently impregnated with resin. The roving then passes through a heated chamber or device J to cure the resin to a hard solid, and then on to a pair of synchronous cutters arranged to cut the roving in the centres of both the bonded and unbonded sections. The product of this continuous process is small brushes or brushlets which are most suitable for automatic handling and collation. In this way brushlets of the same or differing fibre types and diameters can be automatically bundled, to give a brush of given cross section width and stiffness.

The wheels F and G can be of convenient diameter to make the projections H and the spaces between the projections suitable for any required bonded and unbonded fibre length to accommodate the requirements of brushes to be made.

According to the invention there is provided a number of interchangeable wheels with appropriate projections and spacings to enable manufacture to be quickly changed from one brush type to another.

The spacing and timing of the cutters K may also be simply adjusted to cut in the correct places when different

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spacings are used. Synchronising the wheels and cutters may be achieved by many well known methods using cams, gears and chains, and thus will not be described in detail.

If preferred, the glue may be applied to the roving by two oscillating pads, continuously fed with glue, conveniently coupled to the cutter mechanism, see figure 3a. This assembly can replace wheels F and G.

This method allows novel and automatic methods for producing a finished brush one of which, by example only, is shown in figure 5. Here L is one or a bundle of long brushlets, and M short. Both are pre-bonded according to the method as described above along the length bounded by N. The assembly may then be pressed together and dipped in resin along the length N. When the resin is cured the length N will form a handle which can either be left as is or covered in an outer sleeve. The handle may also be formed by casting rather than dipping if a particular shape is required. In this case the bonded bundles bounded by N will be lowered into a mould prefilled with a suitable resin or plastics material, and the whole left to set.

Figure 6 shows a further development which can be easily assembled from brushlets made as described above.

The shaded areas O are bonded areas, and the brush made from automatically collated brushlets of different lengths, being R1-R4, R2-R4 and R3-R4 respectively.

A strengthening sleeve Q in the form of a hollow, flattened, truncated pyramid is shown as a dotted outline for the sake of clarity. Q extends between points R3 and S. When the large brush thus formed finally wears down or becomes unusable, cutting along the line R3-0, and stripping back the sleeve Q to the line R2-0, where it may be conveniently perforated, exposes a new and smaller brush for continuing use. Cutting again along the line R2-0 and stripping Q entirely to S allows a further brush to be


expo s ed .

Judicious choice of brushlet fibre combinations will enable each brush to have its own and desirable characteristics of length and stiffness.



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