Paint brush with improved grip construction and method of manufacture thereof

A brush handle is disclosed having a core member which is surrounded by a layer of compressible and resilient gripping material of a non-slip nature, the layer of gripping material closely conforming to the contour of the brush handle and being mechanically interlocked to the handle by projections which are integral with the core member and extend into the layer of gripping material, and also at least partially bonded one to the other by heat and or chemicals. A brush having the above described handle sealingly secured to a brush head utilizing the layer of gripping material and a method of manufacturing a brush handle are also disclosed.

This invention relates generally to paint applicators, and specifically to 
paint brush handles, paint brushes and methods of manufacture thereof 
which result in a handle, and a paint brush, having an improved grip 
construction and other operational and manufacturing advantages. 
BACKGROUND OF THE INVENTION 
Currently available paint brushes are usually made with a rigid handle, 
often wood, but also plastic, to which a series of natural and/or 
synthetically formed brush filaments are secured, usually with a ferrule 
at the brush filament-handle junction area, using adhesives, fasteners, 
such as nails, crimping, or other means. Such brushes are extensively used 
by do-it-yourself painters who paint on an occasional basis as contrasted 
to a professional painter or decorator who paints day in and day out. The 
do-it-yourself painter is thus unaccustomed to the use of hand, wrist and 
forearm muscles that are called into play in painting with the result that 
painting becomes a difficult, and sometimes painful, task for such an 
occasional painter. The same difficulties may not be so pronounced with 
professional painters but they still are a factor, particularly near the 
end of a day of painting. 
Brush makers have long been cognizant of this problem and attempts have 
been made to overcome it. The most common approach is to manufacture the 
brush handle in the form that experience tends to indicate is the most 
suitable for the specific use for which the brush is intended. Thus, for 
sash work a long straight handle has been preferred. For general painting 
purposes a semi-beaver tail contour has been widely used, and for large, 
wide surfaces, such as exterior siding, a full beaver tail contour has 
been preferred. Although these shapes do result in a rough match between 
the applicator and the painting task when such factors as flow and rate of 
spreadability are considered, nearly all styles include a handle made of a 
relatively hard, rigid material, such as varnished wood or hard plastic, 
and hence the problem of hand and forearm fatigue remains a significant 
drawback. Although attempts have been made to provide a brush having a 
less taxing operational characteristic, no system which is applicable to 
all handle contours and which combines sureness of grip, gentleness of 
contact with the user's hand and ease of use (in the sense of decreasing 
hand, wrist and forearm pain and stiffness in lengthy painting tasks) has 
come into widespread use. 
Another general problem common to many if not the great majority of brushes 
currently in use is the degradation of the brush during use with 
consequent deleterious effects on both the brush, the user and the 
painting surface. For example, in many if not the great majority of 
current brushes the ferrule at the brush filament-handle junction area 
works loose and paint can enter the opened areas and solidify. And in use, 
water, solvent, or paint, or combinations thereof, which have entered the 
opened spaces, are able to re-emerge and run down the handle toward the 
user's hand, thus making a mess and possibly dripping an unwanted color 
onto a freshly painted surface. 
A further annoying and dangerous problem occurs when portions of the end of 
the ferrule nearest the handle are dislodged from their normal lay-flat 
position, thus presenting an exposed sharp edge. This is particularly 
serious when the terminal exposed edge with its associated sharp upper 
corner is displaced away from a snug fitting relationship with the upper 
end of the brush filaments and/or the lower, concealed end of the brush 
handle. Such an exposed edge or sharp corner can easily cut the flesh of 
the user when in sliding contact with the user's hand. 
And finally it is well known that no system for providing the above 
described desirable attributes and avoiding the above described drawbacks 
which is adaptable to the mass production of brushes has been proposed, 
let alone entered the marketplace. 
SUMMARY OF THE INVENTION 
The invention is a paint brush, including a handle, and a handle per se, 
together with a method of manufacturing same, which results in a product 
which significantly reduces fatigue of the user during use, provides a 
sure grip with consequent excellent control over the head of the brush 
filaments during paint application, is applicable to brushes of all 
specialized uses and handle contours from sash to siding, and feels 
comfortable in the hand of the user, yet which can be produced at a very 
modest cost so that mass produced brushes may enjoy the aforesaid 
significant advantages. Said advantages result from the provision of a 
thin layer of material having the characteristics with respect to 
compressibility and flexibility of rubber-like material or soft plastic 
which is preferably formed as an independent molded product about a hard 
handle core. Preferably the thin layer is a thermoplastic elastomer and 
the core is a material compatible with the exterior layer in the sense 
that a good chemical and/or heat bond as well as a mechanical connection 
is formed between the thin resilient layer and the hard core. The handle 
is formed in a two stage injection process in which the core member formed 
in the first stage includes spacer means which fix the position of the 
core member in a subsequent molding cavity so that, upon injection of the 
resilient layer under the necessarily high injection pressures required in 
such operations to form the thin layer of resilient material, the core 
will remain perfectly spaced from the surface of the second mold cavity 
whereby the desired thickness is provided at all locations. The invention 
further includes application of the resilient layer at the junction area 
of the ferrule with the handle in such fashion that problems resulting 
from separation of the ferrule from the balance of the brush are 
eliminated during normal use to which the brush will be subjected. 
Other objects and advantages of the invention will become apparent from the 
following description of the invention.

DETAILED DESCRIPTION OF THE INVENTION 
Like reference numerals will be referenced to like parts from Figure to 
Figure in the description of the drawing. 
Referring first to FIG. 1, a brush, here a sash brush, is indicated 
generally at 10. The brush 10 includes a handle, indicated generally at 
11, a brush head, indicated generally at 12, at the distal end of the 
handle, and a means for securing the brush head to the handle in operative 
relationship, here a ferrule, indicated generally at 13. 
The handle 11 includes a core, indicated generally at 15, see FIG. 3 
particularly, and a thin covering layer, indicated generally at 16, said 
covering layer having the characteristics, with respect to compressibility 
and resiliency, of rubber-like material or soft plastic. The core 15 is 
formed from a relatively hard material, preferably plastic, which provides 
strength and stiffness to the brush. The core includes a shank portion 17 
which terminates at its upper end in hang portion 18 at the proximate end 
of the handle and, at its lower end, in a width expanded connecting 
portion 19. Hang portion 18 has, in this instance, a key hole shaped hang 
slot 20, the bottom of which is formed with inclined surfaces 21, 22, see 
FIG. 3, which form an apex at the center for easily assembly to a hang 
structure, such as a peg board hook or extended wire or Q-bic blade. The 
hang portion 18 is set off from shank portion 17 by a circular channel 
indicated generally at 23, the bottom 24 of the channel 23 extending 
outwardly from the central axis of the handle a slightly greater distance 
than the upper end of the shank portion 17 of the handle for a purpose 
which will appear hereafter. 
The lower expanded portion 19 of the handle terminates in a plug-in section 
of the ferrule cavity indicated generally at 26 which is received at the 
upper end of ferrule 13 in a conventional manner, the plug section 
including side prongs 27, 28. 
The covering 16 is composed of a material having the characteristics with 
respect to compressibility, resiliency and flexibility of rubber-like 
material or soft plastic. As best seen in FIGS. 1 and 3 the covering 16 
extends from the channel 23 downwardly over all the exposed surface area 
of the shank portion 17 and expanded portion 19 of the core, with one 
exception to be described hereafter, above the top of ferrule 13. It will 
be noted from FIG. 1 that, in addition, the covering extends in a narrow 
band 31 along the upper end of the plug section 26 of the core, the narrow 
band 31 being located within the upper edge portion of the ferrule. It 
will be seen from FIG. 1 particularly that the width of the band 31 is 
slightly shorter than the width of the covering 16 at the lowest point of 
the expanded portion 19 of the core. Since the width dimension of the 
lower end of the covering on the expanded portion 19 of the core 15 is 
equal to or, preferably, slighter greater than the thickness of the 
ferrule 13, the joining surfaces of the covering 16 and the narrow band 31 
form a recess having a depth, in a width direction, at least as great as 
the thickness of the ferrule. Thus the narrow band 31 and the adjacent 
shoulder on the covering form a seal with the upper end of the ferrule, 
which seal precludes entry of fluids into the interior of the ferrule, or 
the leakage of paint or other applied coating, upwardly over the upper 
edge of the ferrule from its interior. 
The covering 16 extends downwardly in a suitable recess in the center of 
the core as at 32, loops under the bottom center of the core at 33, see 
FIG. 3, and extends upwardly, as at 34, in a suitable recess on the bottom 
side of the core, see FIG. 3, to form a loop connector between the 
covering on the top and bottom sides of the core which mechanically 
precludes separation of the covering from the core. 
The upper edge of the covering 16, indicated at 35, partially abuts against 
a shoulder 29 formed just below channel 24 whereby slippage of the 
covering 16 toward the hang portion 18 is resisted. 
A finger grip indentation is formed in the lower end of the handle in the 
junction area between the shank portion 17 and the expanded portion 19 of 
the core on both sides of the handle as best seen in FIG. 3. Concave areas 
37, 38, of covering 16 follow the contour of the finger grips 36 so that 
the user may place his thumb and forefinger into the two finger grips 37, 
38 during use. This placement of the finger grips 37, 38 in the 
illustrated very close juxtaposition with the bottom of the handle and top 
of the ferrule provides near-maximum control of the brush head 12 by the 
user during coating application. The locations of the finger grips further 
ease the muscle strains which manipulation of a paint brush entails in 
that the grips provide a more natural less stressful position for the hand 
to occupy during manipulation of the brush head 12 during coating; i.e.: 
as contrasted to the conventional wider spacing usually found on current 
brushes. By reference to a straight cylinder handle as the most 
disadvantageous grip construction, it will be appreciated that the herein 
disclosed configuration consisting of, firstly, a barrel section to 
accommodate the wrap of the last three fingers of the user's hand, in 
conjunction with, secondly, the finger grips 37, 38, provide the most 
natural and therefore the least tiring hand gripping configuration. 
From FIGS. 2 and 3 it will be noted that the thickness 39 of the junction 
area between the shank portion 17 and the expanded portion 19 of the core 
is less than the thickness of the bottom portion 19 of the core. By 
providing a thickness 36 between the finger grips 37, 38, which is only 
thick enough to provide the minimum required rigidity and structural 
integrity to the brush, brush filament control is enhanced because of the 
relatively small distance between the thumb and forefinger of the user in 
operation as contrasted to the spacing between the thumb and forefinger in 
a conventional brush handle. It will be appreciated that the closer the 
two digits of the human hand are placed during a manipulating movement of 
the hand, the finer the degree of control the user has over the gripped 
object. The crescent shaped inclined surface 43 on the lower portion of 
the handle functions as an aesthetically pleasing transition section 
between the narrow dimension represented by the thickness 39 in the finger 
grip area and the substantially greater dimension 41 in the ferrule-handle 
joinder area. Other configurations, including a sharp right angle, could 
be used however. A plurality of grooves are indicated at 44 in the cover 
16. The grooves 44 provide a thumb rest for the user in the event the user 
finds it more comfortable during use to place his thumb on the bottom 
portion 19 of the handle than in a finger grip 37, 38. The grooves also 
function as a means for preventing slippage of the user's thumb, or other 
finger, which may rest thereon in preference to one of the grips 37, 38. 
Said grooves are aesthetically pleasing to the eye but, from a functional 
standpoint, they could be replaced by numerous other constructions, 
including dimpled depressions or a knurled configuration. 
The ferrule 13 is of conventional construction and is applied in 
conventional fashion to the lower end of the handle, the exposed vertical 
edge of the ferrule being indicated at 45. In this instance the ferrule 
has been secured by crimping to the brush head 12 and handle 11, though 
nails could be used. 
A particularly unique feature of the invention is illustrated in FIGS. 1 
and 3 by the core projections 46, 47, 48 and 49. As best seen in FIG. 3, 
projections 48 and 49 extend outwardly to the plane of the surface of 
cover layer 16. The projections are preferably formed integrally with the 
core 15 during the core molding operation. The projections are here shown 
as diamond shaped, see FIG. 1, but it will be appreciated that virtually 
any contour is feasible, including a circle. The protrusions greatly 
facilitate the manufacturing process in that they make possible the 
production of a uniform product at a high rate of speed, and thus make the 
invention available at a price which the mass market consumer can afford. 
The protrusions, here diamond shaped, also function as a further 
mechanical interlock between the core 15 and the covering layer 16 to 
thereby prevent slippage between the core 15 and the cover layer 16. 
Specifically, after molding the core, including the projections 46-49, the 
thus formed core is placed in a second mold cavity and the cover layer 16 
injection molded is about the core 15. In view of the thinness of the 
cover layer 16 and the long distance the hot injection material must flow, 
and the resultant requisite high pressures encountered during the cover 
molding step, the core 15 must be braced away from the surface of the mold 
cavity to ensure that the cover layer material envelopes the core to the 
desired thickness at all locations. The projection 46-49 serve to locate 
the core 15 at the desired position within the second molding cavity, the 
projections thereby functioning in effect as spacers to maintain the core 
in a precise, pre-determined position with respect to the second molding 
cavity. The projections are here configured so that the surfaces thereof, 
as indicated at 50, see FIG. 3, abut the wall of the second molding cavity 
so that injected material may flow around the projections as indicated in 
FIGS. 1 and 3 but not between the surfaces of the projections and the 
surface of the mold cavity. As a consequence the surfaces of the 
projections are flush with the surface of cover layer 16 and provide an 
eye-pleasing, decorative appearance. 
Referring now to the embodiment of FIGS. 5-7 it will be seen that a general 
purpose semi-beaver tail varnish or wall brush is there illustrated. 
Similar reference numerals have been used to refer to parts which are the 
same as or similar to the corresponding parts illustrated in FIGS. 1-4. 
In this instance only a single pair of protrusions 52, 53, have been used 
for the reason that the core is sufficiently short that it may be 
maintained spaced from the wall of the second cavity with only said pair 
of protrusions. 
In this instance also the lower edge of the exposed portion of cover 16 in 
its final condition projects outwardly beyond the thickness of the ferrule 
13 a significant amount, as indicated in 59. Thus even if the ferrule 
should work loose slightly at its upper edge, said upper edge will still 
be within, or aligned with, the exterior dimension of the cover 16 and 
thus the risk of injury to the user, or the ingress or egress of paint, 
solvent or other liquid between the cover 16 and the ferrule 15, will be 
decreased over the structure illustrated in FIGS. 1-4. 
The thickness of the soft grip covering 16 will vary from a thickness of on 
the order of from about 0.030 inches to about 0.125 inches. Below 0.030 
inches it will be difficult to push the material over the length of the 
core 15 through such a small space. If the cover material is thicker than 
about 0.125 inches the flow will be excellent, but the final structure may 
be too flexible for easy use, and the cost would increase considerably 
since the cover material is more costly than the material from which core 
15 is made. More preferably, the thickness of the cover material 30 should 
be on the order of from about 0.050 inches to about 0.075 inches. 
The core material is preferably polypropylene. The preferred over-grip or 
cover grip material is a thermoplastic elastomer (TPE). An example would 
be Santoprene, which is a polypropylene based TPE with vulcanized rubber 
dispersed in it. Since both materials are polypropylene based, there will 
be a better chemical and/or heat bond between both substrates than there 
would be with dissimilar materials. It will be understood that a bond may 
be formed by heat fusion or chemical reaction or both heat fusion and 
chemical reaction depending on the specific materials, times, temperatures 
and pressures utilized. Most preferably the cover 16 is secured to core 15 
not only by the mechanical interlocks but also, to some degree, by a bond 
provided by heat and/or chemical means. 
Other materials could be used for the core material, such as a polyethylene 
with the Santoprene TPE over-grip. Both materials are in the polyolefin 
family and would bond and work, but probably not as well as the same 
material based components. Other base materials such as blends of 
polypropylene and polyethylene could also be used. 
Still other material combinations could be used. For example, Krayton is a 
styrene based TPE which could be used. It would not be as effective as 
Santoprene since the base material is styrene which does not have nearly 
as good solvent resistance to paint solvents as does Santoprene. It would 
be acceptable for latex or water based systems but not solvent based 
coatings. Polyvinylchloride (PVC) can also be used but like Krayton the 
PVC has limited resistance to non-water based solvents. A number of other 
core and over-grip materials could be used to make this type of brush 
handle but the materials described above both have a relatively high 
resistance to all paint solvents and a low manufacturing cost for an 
integrally molded handle. 
As mentioned, the foregoing description pertains to a two-shot molded 
handle. Other handle designs could also be used such as sliding a 
premolded sleeve of a grip material over a core handle. A TPE, PVC, 
polyester or urethane foam or even a rubber material could be slid over a 
core handle. This slide on could be similar to a bicycle handgrip or it 
could be mechanically trapped in a recess but significant disadvantages to 
said alternative processes exist to the point where the illustrated and 
described construction is much preferred. 
Although a preferred embodiment of the invention has been illustrated and 
described in the foregoing specification, it will at once be apparent to 
those skilled in the art that the modifications and improvements may be 
made. Accordingly it is intended that the scope of the invention be 
defined by the scope of the hereafter appended claims when interpreted in 
light of the relevant prior art, and not by the scope of the foregoing 
exemplary description.