02-15-2022, 02:28 AM
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There is more to revolutionising shaving than coming up with a innovative new razor. You’ll need to make machines for making blades. You need to find a way to pack the blades. You have to find way to present your wares. And you need a way to make an affordable shaving brush handle.

And the last bit is what Ernest Miltner filed a patent for in 1910. Filed on behalf of the Rubber & Celluloid Harness Trimming Co, the patent was granted in 1913. Even if it’s tangential to the act of shaving, I find it interesting enough to cover.

It is worth keeping in mind that artificial materials were a fairly new thing. Processes we are familiar with were new, or not even though of. Today “plastic” usually means a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. In the early 20th century, plastic usually meant celluloid – although Bakelite was recently invented.

Celluloid – a mixture of nitrocellulose* and camphor – is commonly considered the first thermoplastic. And that means that it can be moulded by heat… which is just how Ernest turned a tube of it into a shaving brush handle.

Referring to the patent and the drawings, the process is – in hindsight – easy to grasp.

One end of a celluloid tube is upset^ to the diameter of the bottom of the brush handle. A celluloid disk is attached to the wide end. The tube, now closed at one end, is places in a heated mould, and the tube is blown into the shape of a shaving brush handle by pressurised air.

[Image: US1052081-drawings-page-1-697x1024.png][Image: US1052081-drawings-page-2-697x1024.png]
Patent drawings from US patent 1,052,081, showing how to make a celluloid shaving brush handle.

The resulting handle is hollow and light weight, and can – according to the patent – be used while hollow, or filled with plaster of Paris or other materials.

The actual claim in the patent is a bit more verbose though. To qoute:

Quote:The method described of producing a hollow shell of definite outline from plastic material which consists in forming a tube of such material open at both ends, expanding one end portion of said tube, uniting to said end of the tube a closing disk of the same material, applying said tube thus formed within a die or mold, softening the tube therein by heat applied to the exterior of the die or mold, expanding the tube against the-walls of the die or mold by air underpressure delivered within the tube through its open end, and applying a cooling medium to the mold to cool the same and the shell therein.

I don’t think too many shaving brush handles are made in this manner today. But cheap, plastic handles are often injection moulded, which can be seen as a spiritual successor to this process. It should also be possible to recreate the process on a small scale, if an artisan wishes to make old style, plaster filled celluloid handles today.

The full patent can be read, as usual, on Google Patents.

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/edit: Forgot the footnotes:
*) Also known as gun-cotton, which says a fair bit of it’s tendency to go Boom.
^) Upset in this context means widening out into a cone.

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 02-15-2022, 02:24 PM
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  • chazt
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  • Queens, NY
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Hans, where do you suppose 3D printing fits into the mix?

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 02-16-2022, 01:00 AM
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(02-15-2022, 02:24 PM)chazt Wrote: Hans, where do you suppose 3D printing fits into the mix?

Additive manufacturing is a fairly recent development when it comes to non-metals...

That said, you could - today, mind you - extrude a similar hollow handle. I would not use celluloid to do so though, unless I wanted to set my workshop on fire...

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