Micromechanics: how the fountain pen works

In fountain pens, atmospheric pressure does not allow ink to pour out. If you type in a straw for cocktails of water and hold one end, then the water will be securely locked in it. But this technology works as long as the pressure is stable. If you get on a plane with such a straw, then some time after take-off, some of the water will still pour out, since at a height in the cabin the pressure drops by about 25%. In the case of a fountain pen, an ink spot would form in the pocket area.

The most important part of the non-leaking fountain pen - the feeder - is partially or completely hidden under the pen. At the top are one or, as in Monblanc pens, two capillary channels through which ink flows to the pen. The edges of the feeder act as a kind of buffer on which excess ink accumulates and from which, in case of increased ink consumption, reserves are taken. Ink is retained on the edges due to the capillary effect. Despite the apparent simplicity, the solution is very non-trivial, requiring an extraordinary knowledge of mechanics and physics.

However, it is not necessary to take off for a catastrophe with an ink stain - a normal fluctuation in atmospheric pressure or a slight concussion is sufficient. To prevent this from happening, a rather witty solution was invented - a feeder with a ribbed collector. All excess ink due to the capillary effect was retained on the ribs. The feeder also performed other functions - ink was sent to the pen through a channel, the cross section of which determined the speed of their receipt. Since the ink consumption was not constant when using the pen, the collector also served as a kind of buffer.

There are a huge number of feathers suitable for a variety of writing styles. Classic, with a spherical tip, differ in its diameter - from EF (Extra Fine - 0.3 mm) to BB (Extra Bold - over 0.8 mm). Feathers with a flat end, which can also be chamfered under the left or right hand, are used for calligraphy.

An equally important part of the pen is the pen, the comfort of using the tool and the beauty of writing depend on its quality. The best Montblanc feathers are made from gold leaf alloy with a variable thickness - from 0.18 mm at the base of the pen to 0.52 mm at the tip. This provides an easy springy moment, well known to Montblanc owners and enhancing writing comfort. The body of the pen is stamped, bent, polished, engraved and welded the tip of a harder metal. After that, they give him a certain shape that matches the style of writing, from the traditional sphere to the beveled flat tip for calligraphy. Some Montblanc boutiques have computerized systems that allow you to give out unique parameters of your writing style after the test task, by which you can choose the pen that is most suitable for you, and with a great desire and budget, make a unique pen specifically for you.

One of the final operations is performed by the thinnest diamond saw. It is this almost invisible cut due to the capillary effect that delivers ink to the tip and paper. It remains only to manually polish it and insert it into the pen.

The article "Micromechanics" was published in the journal "Popular Mechanics" (No. 5, May 2017).

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