Well, shaving brush with disposable knot, to be precise.

Like so many others – Edward L Corbet, John T Cooney, Marguerite Faučon, and Aron Braunstein & Angel Rattiner to mention just a few – inventors, Gustav Koch searched for a sanitary, hygienic, and disposable shaving brush. If it worked well for making lather, it was a bonus. If it dodn’t need a cup, that would be one less unsanitary item to worry about.

To quote the patent:

My invention relates to shaving-brushes, and has for its object, first, the production of a device for creating and applying lather to the face of a person about to be shaved, wherein the part constituting the brushing element is adapted to be detached and discarded after once using, and, second, to avoid the necessity for employing a shaving cup and soap by making each detachable brush element carry or contain a sufficient charge of soap for one shaving operation by coating or impregnation.

So a disposable ‘brushing element’ infused with soap. Calling it a brush knot would be overstating things, as can be seen from the drawing and the text description.

…the brush-cloth or fabric-disk is shown with a fringed edge made by radially slitting the disk; but I do not confine myself to the detail of the fringe and may prefer to use the brush-disks without fringe. Any fabric, soft leather, cloth, or felt can be used as brush-disks, and two or more of the disks can be employed at one time to provide a greater tuft for the application of lather. As the middle portions of the disks are drawn into the enlarged mouth O of the handle the edges, whether fringed or otherwise, are caused to project from the handle downwardly, as shown in Fig. 2, forming the disks into a brush for applying lather to the face.

To use, a barber would push down on the spring loaded plunger that can easily be seen in the drawing. This would make a small hook project out of the base of the brush handle. The barber would hook the round brush cloth, and let go of the plunger. This would pull the middle of the disc into the handle, making the fringed end stick out like the saddest brush knot ever.

After wetting it and trying to make lather with the soap saturated cloth, the barber would push the plunger again and dispose of the disposable brushing element.

It is easy to sit snuggly over a hundred years after the big anthrax shaving scare and be snarky. But no matter how you cut it, Gustav’s disposable brushing element is one of the more awkward and probably less well thought out solutions to the germ problem.

You can read the full patent for Gustav’s somewhat disposable shaving brush at Google Patents.