Twisted wire brushes for application of liquid-type cosmetics, such as for application of mascara to the eyelashes, are well known in the prior art. Such brushes are designed to pick up and hold a supply of mascara from the cosmetic container, and then deliver the mascara to the eyelashes as the user combs the brush through the lashes.

Twisted wire brushes conventionally are manufactured by disposing a plurality of individual lengths of bristles transverse to and between substantially parallel, slightly spaced-apart thin metal wire lengths, such that the wire lengths generally bisect the bristle filament lengths at their midpoints. Most typically, the parallel wire lengths comprise two substantially equal leg lengths formed from bending a single length of wire into a U-shaped configuration. The wire lengths are then twisted together to form a helical core, causing the bristles disposed between the wires to be clamped therebetween at about their midpoints. In the twisting and clamping, the segments of the bristles on either side of the clamped midpoint are caused to flare radially outward from the core and so form an elongate bristle brush portion of generally circular cross-section. The bristles are usually comprised of nylon filaments. The

bristles serve the function of collecting mascara from a reservoir and holding the mascara until it is applied to the user's eyelashes. The brush is generally affixed to a rod, which is mounted to a cap or other closure for the cosmetic container.

Typical mascara brush designs use metal wire having a diameter of 0.61 mm to 0.71 mm. These wires, when twisted, provide a pitch of 2.54mm to about 3.43 mm (e. g. a separation of 2.54 mm to about 3.43 mm per full 360° turn of a leg of the wire core). The bristles used with these wire cores have ranged in size from very small diameter bristles, to standard diameter bristles in the range of 0.10 mm to 0.15 mm, to larger diameter bristles in the range of 0.20 mm to 0.33 mm (4 mil to 10 mil).

It has been suggested in the prior art, that the combing effect of a mascara brush may be improved by using fewer bristle fibres per full 360° turn of the wire core of the mascara brush. However, if bristle fibres of conventional diameter are used to manufacture such mascara brushes, it is difficult to ensure that the bristle fibres are distributed evenly thoughout the pitch of the twisted wire core. For this reason, the prior art suggests the use of bristle fibres having a larger diameter, but this may not be suitable for all mascara compositions.

Another issue that has arisen with these known brush designs is that the diameter of the brush core limits the

size of the rod to which the brush core can be mounted.

In typical mascara packaging, a wiper assembly is provided at the mouth of the mascara container. The wiper removes mascara from the rod as the brush is withdrawn from the container. The wiper typically will wipe the outer portions of the brush bristles, allowing mascara product to be carried out of the container in the inner zones of the brush.

It is not possible to use a larger diameter rod with conventional brush assemblies without an excessive amount of product being left on the inner core of the brush when the brush is withdrawn from a product container. The typical upper limit to a rod diameter is 4.3 mm, and often it will be less. The typical mascara rod diameter is in the range of 3.6-4. 0 mm. A larger diameter rod will require a wiper with a larger diameter aperture.

The larger diameter aperture of the wiper will not wipe as much of the inner portions of the brush, leading to excessive loading of mascara product on the brush, with subsequent messy application of the product to the user's eyelashes. This limitation means that the rod cannot be made as sturdy as it could be, and prevents use of a design option that is desirable in some brush packaging designs, especially when used with high viscosity mascara products.

It is an object of the invention to provide a mascara brush design providing a good combing and lash separating effect without requiring use of larger

diameter bristle fibres or low bristle counts. Thus, the invention aims to provide a mascara brush suited for the use of bristle fibers with a diameter in the conventional range and having conventional bristle densities for each turn of the twisted wire core helix, but which provides good combing and lash separating effect.

Furthermore, it is an object of the invention to provide an alternative mascara brush design, which permits the use of a larger diameter rod without the problems of inferior wiping associated with conventional brushes.

Accordingly, the present invention provides a mascara brush having a twisted wire core holding a plurality of radially extending bristles to form a brush at an end of the core, characterised in that the twisted wire core is formed from a wire having a diameter of about 0.71 mm to about 1.02 mm, and a pitch of about 3.4 mm to about 5.1 mm.

The twisted wire core is preferably made of wire formed of brass, copper or stainless steel, or a plastic coated metal wire. The invention further comprises the method of fabricating the brush.

FIG. 1 is a side elevation view of a mascara brush in accordance with the invention.

FIG. 2 is a side elevation view of the twisted wire core showing the wire pitch.

Referring now to Fig. 1, a mascara applicator brush, designated generally by reference numeral 10, is shown.

The brush is intended for use in a typical mascara bottle (not shown) with an opening into which the brush 10 is inserted.

The brush 10 is comprised of a central twisted wire core 12 containing bristles 14. The core 12 is a twisted wire core typically made by forming a soft metal wire 16 into a"U"shape having segments 18 and 19. A plurality of bristles 14 are placed between the segments 18 and 19 of wire 16. The wire segments 18 and 19 are then twisted around each other along a longitudinal axis to clamp bristles 14 at approximately midpoints of the bristles 14. The bristle ends extend radially from the twisted wire core 12. Core 12 has a lower end 20 connected to a shaft, and an upper end 24 opposite the lower end 20.

The lower end 20 of the core 12 is connected to a handle by way of the shaft, however, the lower end 20 of the core 12 could alternatively be attached to another structure such as a bottle cap.

The wire of the twisted wire core has a diameter of about. 71 mm to about 1.01 mm, and the twisted wire core has a pitch of about 3.3 mm to about 6.35 mm. The pitch is shown at P in FIG. 2. The pitch is the linear distance along the axis of twisted wire core from the

center 30 of wire segment 18 to the center 32 of the wire segment 18 after it has twisted through 360 degrees.

(Note that wire segment 19 appears between the centers 30 and 32). Preferably, the twisted wire core has a pitch of about 3.4 mm to about 5.1 mm.

The wire pitch of the wire core in the present invention is substantially larger than conventional mascara brushes, which have a typical pitch of 2.54 mm to 3.4 mm. The mascara brush has a relatively high bristle density, in the range of about 35-80 bristles per turn. However, the larger pitch of the twisted wire core of the present mascara brush creates an attenuation of the bristles to provide adequate spacing of the bristles to provide good combing of the eyelashes.

The wire is preferably formed of brass, copper or stainless steel, or a thermoplastic coated metal wire.

These different materials behave differently when used in wire twisting machinery, and so particular preferred ranges can be determined by using the following guidelines.

A thermoplastic coated metal wire is effective in the invention, as it provides a larger diameter wire, and thus a greater pitch, without significant difference in the force/torque needed to twist the wire, thus it can easily be adapted for use in typical wire twist machinery.

A stainless steel wire in the larger diameter will have a rather different behavior. The thicker steel wire will be harder to twist, and thus this wire will have the highest pitch for a given set of twist machinery settings. Brass or copper wires are softer and will have relatively lower pitches at the same settings.

It is also possible to increase the pitch by providing tension to the wire ends during the twisting step. This tension will stretch the wires and increase the wire pitch.

After the bristles 14 are mounted to the wire core 12 the brush 10 can be trimmed to have any desired shape, for example, cylindrical, tapered, conical, curved, etc.; or if desired, the bristle ends may be processed by grinding, heating, or other techniques.

Bristles 14 are preferably made by cutting short segments from spools of filaments. The filaments are preferably formed from nylon or polyester, or another suitable material. The filaments will typically be circular solids in cross-section, but alternatively may have non-circular cross-sectional shapes, such as ovals, square, rectangular, or polygons (including hexagons); or the bristles may have voids therein, thus, the term "diameter"as used herein to refer to"bristle diameter" is intended to mean the maximum distance between any of the possible opposite positions on the outer surface of a bristle filament. The bristle lengths may be slightly

longer than is usual in conventional brush designs, but this is not a necessary requirement for effective use of the invention.

The steps of fabricating the mascara brush 10, in essence comprise placing bristle filaments in a U-shaped wire which has a diameter of about 0.71 mm to about 1.02 mm and twisting the U-shaped wire to form a twisted wire core to a pitch of about 3.3 mm to about 6.35 mm. In one preferred embodiment, the twisting forms a wire core with a pitch of about 3.4 mm to about 5.1 mm.

The brush 10, when fabricated, is then assembled together with a rod (40). The rod (40) may have a diameter in the range of about 2.54 mm to 6.35 mm, more preferably about 3.18 mm to 4.44 mm. These rod diameters provide a sturdy rod that will not be prone to breakage or bending, or deformation through creep. The larger diameter core of the brush prevents excessive loading of mascara product on the brush 10 that would occur with a smaller diameter wire core were matched with a rod of this size.

While the invention has been described and illustrated as embodied in preferred forms of construction, it will be understood that various modifications may be made in the structure and arrangement of the parts without departing from the spirit and the scope of the invention recited in the following claims.