What materials is the ink feed made of and what is its role in the functioning of the fountain pen?
A Law of triviality According to Wikipedia, „it means that members of the management in an organization tend to discuss various topics with varying levels of detail, not commensurate with their weight and cost.”
This rather dry formulation is usually illustrated with a very entertaining example. According to this (a tale follows), the committee leading the city meets to discuss two agenda items. The first item concerns the signing of a multi-billion dollar contract for the construction of a nuclear power plant, which is voted on quickly. The second item proposes the construction of a related bicycle storage facility, in which the committee members delve deeply into the technical details (its material, its painting, etc.) and only reach an agreement after a lengthy debate.
The essence of the story is that people generally prefer to take a stand on issues that are simple and mundane. I find the ABS vs Ebonite ink conductor „committee debate” to be such a matter. Csaba's excellent introduction to ink dispensers – which I hereby recommend to anyone dealing with fountain pens for reading – was concluded somewhere at this point, so I would like to pick up the thread here.
Side note: the Montblanc „Edelharz / Precious resin” legend was very well processed by an Australian university professor in a relevant blog post. But since someone has already visited the page, I suggest reading more of his snippets as they are very interesting and readable.
Before we delve into the details of the ink conductor material, let's take a step back and examine the operation of the fountain pen as a whole.
This is how the fountain pen works
Understanding the operation of the fountain pen (in my case, this is very far from completeness – thus, what is described further is mostly a superficial translation – understand: I borrowed – from what Amadeus W., a German „fountain pen engineer,” wrote in his blog, however, it starts with the ink dispenser, or more generally, the reservoir.
If we think of a simple bottle, then with its mouth facing down, the liquid generally flows out according to common experience. Furthermore, air will take the place of the departing liquid. However, if the air cannot find its way to the place of the departing liquid, then after a small amount of liquid has left, the liquid column will stop in a state of equilibrium. Somewhat like in a birdbath tank:
With this vacuum/liquid column equilibrium, the basic operation of the fountain pen can also be imagined:
If we examine it in more detail, the next step is to immerse ourselves in the beauties of surface tension and capillarity (capillary action – this is where the advertisement goes 😊), so put on your diving goggles!
For a definition, I would turn to Wikipedia again:
Capillarity (in foreign terms, capillarity, capillary action, or capillary effect) is the property of liquids to move in narrow spaces against the force of gravity. This phenomenon can be observed in many places, such as on porous paper, paper towels, capillary tubes, in soil, etc.
Based on practical observation, different liquids „like” the solid materials they come into contact with to varying degrees. According to the illustration above, for example, mercury „does not like” the glass tube it is dipped into, while water, on the other hand, „likes” it just enough, and the narrower the tube, the more it does so. Those who write with fountain pens surely know that the very small gaps – such as those between the fibers of a paper tissue or the fabric of a white shirt – are „loved” by water-based ink.
Here is a graph drawn by nature itself, where water rises between two glass plates, and the smaller the gap between them, the higher it rises.
This physical phenomenon is again a balance, the explanation of which can be found in the phenomenon of surface tension (and weight/gravity).
Surface tension
Let's see what Wikipedia says about surface tension! WIKI! Come in!
A surface tension a fundamental property of liquids that causes them to adopt the shape with the smallest possible specific surface area (sphere) when no external force field acts on them. The reason is the cohesive force between the particles of the liquid (atoms, simple and complex ions, molecules, or smaller aggregates made up of these).
The equation describing this:
I was joking 🙂
This is better told by Mr. Attila Sultis with his own images (with his permission – with respect and grateful thanks from my side):
Let us accept that from the container (bottle) depicted upside down above, if the opening is sufficiently narrow, it will no longer be gravity that draws (or keeps) the liquid out of (or in) the container, but capillarity.
So whether it is a built-in (integrated) filling system, ink dispenser (converter), cartridge, or just the cavity of the pen body (eye-dropper), the path of the ink leading to the nib will be described by the physics of capillarity.
I wrote down this whole theory just so that when we reach our central topic (Ebonite vs. ABS), no one would feel inclined towards theories, physics, equations; even less so towards the picking apart of long molecular chains. So from now on, let this be enough:
Ebonite
In 1852, Charles Goodyear invented hard rubber, which he named ebonite from the Greek word ebenos (έβενος = ebony).
Goodyear produced the material by adding more sulfur to the rubber than was necessary for vulcanization (up to 30%), then heating the well-kneaded mass to 150°C. To increase hardness and elasticity, he later added shellac to it.
Its molecular structure looks like this:
ABS
Acrylonitrile-butadiene-styrene (ABS) is a thermoplastic with good impact resistance, high hardness and strength, good heat resistance, and chemical resistance, belonging to the group of amorphous polymers. It has a high surface gloss, which is why it is most often used as a casing.
It is produced by the bulk or emulsion polymerization of styrene and acrylonitrile in the presence of polybutadiene. This results in long polybutadiene chains with shorter polymerized acrylonitrile-styrene copolymer cross-links.
So in both cases we are talking about polymers – just that one flows out of wood and then goes into the factory while the other only enters there in its components and eventually falls out in the form of bracelets, LEGO™, etc.
Mr. Amadeus W., in his long and detailed dissertation on ink conduits (which he was involved in developing), reviews the interactions of inks, polymers (natural and synthetic), examining the role of the phenomena described above (capillarity, surface tension) in light of different temperatures, pressures, and ink viscosities, all the way to the physical relationship between the nib and the paper, drawing his final conclusion – based on theories and experimental results – that in the case of the two ink conduit variations (Ebonite and ABS), it is not their material but the design of their surface (microgeometry) that is decisive. Thus, it is possible that with the appropriate surface treatment (chemical etching and similar refinements), the ABS ink conduit may perform better than the Ebonite.
Those who do not believe my translation, can read the original in English here.
Alternatively, if someone wishes to delve into the world of solid surfaces in contact with water, I would recommend the Wikipedia hydrophobic and hydrophilic entries related to these keywords:
I also confidently recommend „The Action Lab's” spectacular demonstration of hydrophobic paper sprinkled with hydrophilic powder (seasoned with a bit of etymology).
Furthermore, if someone is really just curious about the visuals, I can recommend the water-bouncing water droplet video by the duo „The Slow Mo Guys,” one of my favorite channels.
After this, I dare to suggest regarding the Ebonite/ABS ink feed issue that the committee meet at the next club meeting and finalize the discussion there at the session!
Acknowledgments
- With heartfelt thanks to Mr. Amadeus W. „fountain pen engineer” for Fountain Pen Design his monumental work in understanding and explaining the functioning of fountain pens. You can read his personal story here
- to Mr. Attila Sultis, architect, for his continuous work in presenting the visual world of fountain pens in the most beautiful way possible.
- To the unknown authors of Wikipedia for their tireless work in sharing the world of knowledge in the most comprehensive and democratic way with the inhabitants of our planet!
