Patent Publication Number: US-2004045407-A1

Title: Sharpening strop for cartridge type razors

Description:
FIELD OF THE INVENTION  
       [0001] The present invention lies in the field of shaving razors, particularly those of the cartridge type, that are in virtual universal use for wet shaving nowadays.  
       BACKGROUND  
       [0002] Whereas the old “cut throat” razors of previous generations were routinely sharpened, the advent of replaceable razor blades that were fitted conveniently to a razor virtually eliminated sharpening, as the blades could be economically replaced. These blades have in turn been replaced by multi-blade cartridges, which are replaced as they become blunt. The marketing strategy adopted by manufacturers led to single blade cartridges being replaced by double blade cartridges and they in turn by triple blade cartridges. This strategy resulted in escalation of the price of the replaceable cartridges, to the extent that there is now again interest in being able to sharpen the razor blades in cartridges.  
       [0003] The “cut throat” razors were sharpened on leather strops, the technique amounting actually to honing the edge so as to remove burrs from the edge, which result from the shaving action. Leather strops are currently marketed for sharpening knives, under the name “Knifeart”™, www.knifeart.com, comprising a leather strop on a wooden paddle. Honing was also done on a whetstone, a very fine grained stone, to provide a keen edge. U.S. Pat. No. 5,036,731 proposes a special guide with a plate glass member for honing razor blades.  
       [0004] In recent times, proposals have been made by “Razormate”™ to use a magnetic effect by no more than to “simply rest your razor head on this specially-designed ceramic magnet” www.newsearching.com. U.K. patent 2 149 219 proposes a housing with a magnet for sharpening razor blades in cartridges. U.S. Pat. No. 5,329,699 proposes a receptacle with two oppositely charged magnets for extending the life of a razor blade.  
       THE INVENTION  
       [0005] The present invention provides an appliance for sharpening cartridge type razor blades, which comprises a leather strop that is mounted on a magnetic substrate that is in turn mounted on a support, the strop having a length and a breadth, the length for a stroking action of the blades along the strop, the breadth matching the exposed width of the blades in the cartridge and the strop surface being proud of the support surface adjacent the sides of the strop.  
       [0006] The reason for the width of the strop matching the width of the blades in the cartridge is that the edges of the cartridge are slightly proud of the blades and it is necessary that the strop touches the blades when the cartridge is stroked over the strop. For this reason the width of the strop must not exceed the exposed width of the blades in the cartridge and must match that width so that the whole or substantially the whole width of the blades is sharpened.  
       [0007] The surface of the strop must be proud of the surface of the support adjacent the strop edges so that the edges of the cartridge that are proud of the blades do not run on the support and so prevent the blades from touching the strop. The magnetic substrate may also be proud of the support surface adjacent the substrate and strop.  
       [0008] The length of the strop may be a convenient length for a stroking action, pushing the razor while it holds the cartridge over the strop.  
       [0009] Preferably the strop is one that has been vegetable tanned as this produces a leather surface that is effective in honing a razor blade.  
       [0010] Preferably the magnetic strip has a plurality of magnetic pole pairs oriented transversely across the magnetic substrate. The pole pairs are preferably alternately arranged so that on each edge of the substrate the north and south poles of the magnets alternate along the length of the substrate.  
       [0011] The magnetic substrate and the leather strop must be glued or bonded by suitable adhesive or bonding agent and preferably in addition the support has a recessed portion to receive them and an undercut where the ends of the substrate and strop are located, so that the ends of these may be snugly located in the undercuts. This helps ensure that the ends are not lifted up and detachment initiated by the stroking action. The sides of the strop at least must however not be located in an undercut but must be proud of the support adjacent the edges of the strop, as mentioned. 
     
    
    
     THE DRAWINGS  
     [0012] The invention is more fully described by way of an example, with reference to the drawings, in which:— 
     [0013]FIG. 1 is an isometric view of the appliance for sharpening razor blades in a cartridge,  
     [0014]FIG. 2 is an isometric view of the underside of the appliance,  
     [0015]FIG. 3 is an enlarged view of the appliance,  
     [0016]FIG. 4 is an isometric view of the components of the appliance,  
     [0017]FIG. 5 is a plan view of the appliance,  
     [0018]FIG. 6 is a side view of the appliance,  
     [0019]FIG. 7 is an enlarged detail of the appliance, And  
     [0020]FIG. 8 is an enlarged view of a transverse section of the appliance. 
    
    
     THE PREFERRED EMBODIMENTS  
     [0021] As shown in the drawings, the appliance  1  for sharpening cartridge type razor blades comprises a leather strop  2  that is mounted on a magnetic substrate  3  that is in turn mounted on a support  4 . The strop has a length  5  and a breadth  6 , the length for a stroking action of the blades along the strop, the breadth matching the exposed width of the blades in the cartridge. The strop surface  7  is proud by a distance  8  of the support surface  9  (see FIG. 7) adjacent the sides of the strop.  
     [0022]FIG. 3 shows enlarged a typical textured surface of the leather strop.  
     [0023] The reason for the width of the strop matching the width of the blades in the cartridge is that in typical razor blade cartridges, the edges  10  of the cartridge  11  are slightly proud of the blades  12  (see FIG. 8) and it is necessary that the strop  2  touches the blades  12  when the cartridge is stroked over the strop. For this reason the width of the strop must not exceed the exposed width of the blades in the cartridge and must match reasonably closely that width so that the whole or substantially the whole width of the blades is sharpened. For example, a typical width of the exposed part of the blades in a cartridge is thirty-three millimetres (33 mm), however, width between sixteen millimetres (16 mm) and forty millimetres (40 mm) may be catered for.  
     [0024] The length of the strop may be a convenient length for a stroking action, pushing the razor  18  while it holds the cartridge over the strop. For example, a length of one hundred and fifty millimetres (150 mm) is selected for this example, however, lengths between one hundred millimetres (100 mm) and two hundred millimetres (200 mm) may be suitable.  
     [0025] As mentioned, preferably the strop is one that has been vegetable tanned as this produces a leather surface that is effective in honing a razor blade. It has been reported that leather may contain a fine abrasive material that contributes to the honing action, together with the properties of the leather itself. A paste or fluid containing honing substance may be employed if desired, though it is not recommended by the inventor. A vegetable oil may be used on the leather to enhance the effect of providing a sharper edge to a blade of a cartridge type razor.  
     [0026] Preferably the magnetic strip has a plurality of magnetic pole pairs  13  (see FIG. 4) oriented transversely across the magnetic substrate. The pole pairs are preferably alternately arranged so that on each edge of the substrate the north and south poles of the magnets alternate along the length of the substrate.  
     [0027] The magnetic substrate and the leather strop must be glued or bonded by suitable adhesive or bonding agent and preferably in addition the support has a recessed portion  14  to receive them and an undercut  15  where the ends of the substrate and strop are located, so that the ends of these may be snugly located in the undercuts. This helps ensure that the ends are not lifted up and detachment initiated by the stroking action. The sides of the strop at least must however not be located in an undercut but must be proud of the support adjacent the edges of the strop, as mentioned.  
     [0028] The edges of the support that are adjacent to the strop are the edge ridges  9  and between them the support has the recessed surface  14  that receives the magnetic substrate and on top of that the strop. As can be seen in the view of FIG. 8 although the surface  14  is recessed slightly, the greater thickness of the substrate and strop together are such as to ensure that the edges  9  are sufficiently below the upper surface of the strop, for the reason mentioned.  
     [0029] The support includes a handle  16  for holding the appliance and a hole  17  for hanging it if one desires. The support is preferably made by plastic injection moulding technology.  
     [0030] Tests on prototypes by the inventor and collaborators have revealed improvements in life of cartridge razors from a matter of weeks to a matter of months. Work in the art has suggested that magnetic effects on cartridge blades, which are very thin, is beneficial and the inventor&#39;s work has suggested that the particular arrangement according to this invention as claimed enhances this effect and favourably combines it with the beneficial honing effect of a leather strop.  
     REFERENCE NUMERALS  
     [0031] 1 appliance for sharpening blades in a cartridge  
     [0032] 2 leather strop  
     [0033] 3 magnetic substrate  
     [0034] 4 support  
     [0035] 5 length of strop  
     [0036] 6 width of strop  
     [0037] 7 upper surface of strop  
     [0038] 8 dimension that strop is proud of adjacent support surface  
     [0039] 9 longitudinal side ridges of support  
     [0040] 10 edges of cartridge  
     [0041] 11 cartridge  
     [0042] 12 razor blades held in cartridge  
     [0043] 13 magnetic poles  
     [0044] 14 recessed surface for support of substrate and strop  
     [0045] 15 undercut at both ends of surface for substrate and strop  
     [0046] 16 handle of support  
     [0047] 17 hole to hang up appliance