Feb. 7, 2021

22. Learning about fountain pen fluid dynamics from Nicole Sharp

22. Learning about fountain pen fluid dynamics from Nicole Sharp

In today’s episode, we will be talking all about how your favorite fountain pen works.  Behind every design, there is engineering.  Behind fountain pens, there is fluid dynamics and I’m excited to have on as a guest a Ph.D in fluid dynamics.  Her goal in life is to spread the word about fluid dynamics and today she will explain the various ways physics puts ink to paper.

You can find amazing articles that will expand your knowledge of the world of fluid dynamics on her website fyfluiddynamics.com/

 Please welcome, Nicole Sharp!




 Do you have a favorite fountain pen ink?

 Conservative- Platinum Carbon Black
Wild- Looking for the perfect orange
Papier Plume Sazerac
KWZ Eldarado
Robert Oster Australis Tea
Papier Plume Blue Heron 

Endless Recorder
Rhodia Pad

 Pilot Vanishing Pont Matte Black
Sailor Manyo Yomogi
Mnemosyne pad
Sailor Colorado

Can you share one technique with the listeners that you think will elevate their snail mail art?

 21. A visit from the Queen of Washi, Beth Hobson

Are there artists that you think are doing amazing work that stationery lovers need to know about? 

 The forum for Pen and Ink Maps: https://cartographersguild.com/forumdisplay.php?f=110

And the following are all some works done specifically with ink and pen (+watercolors, pencils, etc.):




 Ep 17. Timothy Ely, Artist and Bookbinder at APlanetaryCollage.com Part 1


What is your favorite purchase (stationery or not) in the last 6 months?

Pilot Vanishing Pont Matte Black


If you are interested in seeing more of Nicole’s work you can find her on the Internets at the following places:

 You can find her on Instagram @fyfluiddynamics

And her fountain pen and ink @aerognome

 You can find amazing articles that will expand your knowledge of the world of fluid dynamics on her website fyfluiddynamics.com


Support the show (https://www.patreon.com/stationeryorbit?fan_landing=true)


[00:00:00] John: [00:00:00] Welcome to episode 22 of stationary orbit, where we are all here to learn more about creative letter writing. I'm your host John West. And in today's episode, we'll be talking all about how your favorite fountain pen works. Behind every design there is engineering,  behind fountain pens there is fluid dynamics and I'm excited to have on as a guest, a PhD in fluid dynamics.

Her goal in life is to spread the word about fluid dynamics. And today she will explain the various ways physics puts ink to paper. You can find amazing articles that will expand your knowledge of the world of fluid dynamics on her website, F Y fluid dynamics.com. Please welcome Nicole Sharp. Evening Nicole. So right out of the gates, what is fluid dynamics?

Nicole: [00:00:45] I tend to take a pretty broad definition of it and basically define it as the physics of anything that flows. So whether you're talking about liquids or gases or plasmas, or sometimes [00:01:00] things like sand or snow pretty much anything that isn't fully solid has a its own way of flowing and fluid dynamics is the study of all of that.

John: [00:01:11] Very good. Yeah. I was  geological engineering major in college. So the biggest part of that I got was fluid mechanics, which is all about calculating head and head flows. So there's an awful lot of what you're going to be talking about today. That's probably well above my head.

So what is one of your favorite examples of fluid dynamics and how it enables our modern world?

Nicole: [00:01:37] For me, one of the things that is most fun about fluid dynamics is that you can pick almost any situation you can imagine. And I can find a way to connect it to fluid dynamics. I mean, yeah, right now you and I are sitting here and we're transmitting our words to one another using pressure waves that are emanating from our  mouths. [00:02:00] And that's an example of fluid dynamics. Our hearts are beating inside our chests and creating turbulent flow within. Our heart chambers and that's key to us being alive. Out on the street, there are cars going by and aerodynamics are an important key part of how they slice through the air.

And internal combustion is what's making them run. So really we have fluid dynamics around us. All the time, literally from the moment you wake up or even the moment before you wake up, you get up, you brush your teeth, you jump in the shower. There's fluid dynamics everywhere.

John: [00:02:39] Yeah, including your HVAC system, which is airflow and that's different compressible fluid. But it's a fluid all the way. All the same.

Nicole: [00:02:46] Yup. Yup. Liquids and gases. Those are our two primary categories.

John: [00:02:52] Yep. So we're often told that fountain pens work by capillary action. What is capillary action and how does it work in [00:03:00] fountain pens?

Nicole: [00:03:01] so capillary action is a fancy name for intermolecular forces.  

Essentially the molecules inside the ink and the molecules inside the material of say your nib or your feed exert forces on one another. And if you can imagine your ink sitting in the bottle it's surrounded entirely by ink molecules and being pulled the same way in every direction.

Whereas whenever you take ink and you put it next to. Say an ebonite feed. You're going to have very different forces being exerted by the molecules in one of those materials on the other.  

And so that is  where we're fundamentally capillary action is coming  from more of a macro perspective. So what we see capillary action is the tendency of a liquid to flow into narrow spaces.  

And a fountain pen that's flowing in between those fins and the feed [00:04:00] and up through the slit in the nib and out onto your page.

John: [00:04:04] And I think it's an important distinction to be made that when we're talking about capillary action, especially on a macro level, is it the way most people encounter it is the non-intuitive way that it actually draws fluids up into a surface, up into soil or up into a feed and onto a nib.

Nicole: [00:04:28] yeah.  Or into your straw. So if you  have a transparent straw, you can see that the water level inside the straw is usually higher. Then whatever liquid you have the straw in and that's because capillary action is drawing the water,  up the sides of the straw.

John: [00:04:44] Nice.  When I was getting ready for my fountain pen ink, Primer. I was doing a lot of looking around on Wikipedia and Wikipedia for as much information as it has out there does have some real drawbacks to it. So on the Wikipedia [00:05:00] page, they were talking about different comparisons of surface tension and they use distilled water and fountain pen ink as examples.

Is this an accurate way to talk about fountain pen, inks and capillary action.

Nicole: [00:05:14] Sure. So surface tension  is really close, mostly related to capillary action.  

It's also related to intermolecular forces and the fact that when you have dissimilar materials, you get dissimilar forces on either side. And that creates this effect. That makes it seem like. Say a bead of water has tension across it  like a balloon.

So surface tension typically depends on not just what the liquid is, but what gas is surrounding it. If there's a gas and what material it's sitting on, which is why you can get water that looks like it's almost flat on some surfaces, like a drop of water. It looks flat on some surfaces  and looks like a little sphere on others.

 So technically all of the surface tension [00:06:00] measurements , should in theory, take into account the three materials that are meeting the solid material, the liquid that you're interested in and whatever gas may be surrounding it,  practically speaking, we tend to not to get quite that specific.  

For example, we just assume that there's air around whatever it is.

 What is fountain pen ink?  Fountain pen ink  is largely water. But it has a lot of other extra stuff in it. It has dyes, it has potentially pigments. It definitely has surfactants, which are molecules that are designed to specifically lower the surface tension. And  they collect that at the surface of  the interface between the ink and air.  You also end up having things like  chemicals that are meant to try to get rid of any mold or fungus that might try to grow in the fountain pen ink. Basically. Water distilled water is going to have a pretty high surface tension. [00:07:00] That's just a characteristic that water has. And when you start adding additional things to water, you lower the surface tension  and fountain pen ink ; therefore is yes. Going to have a significantly lower surface tension, which is good because  you actually do want it to flow in order to get that capillary action and get it out of your feed and your nib and onto the paper.

John: [00:07:23] Okay. So one of the things that I noticed in the Wikipedia article is that they were referring to dyn per centimeter measurements. And I know that dyn per centimeter is part of a legacy version of   our current system for  the metric system and the a legacy system of units. But could you give us some other dyn per centimeter measurements that can help us relate to the numbers that they listed for distilled water and fountain pen ink.

Nicole: [00:07:51] so I think  what's probably easier is not necessarily to talk in specific numbers, but to think about some different liquids  that might have [00:08:00] similar surface tensions. Granted, I haven't checked to see how viscosities between these vary.  

So I should probably say that this viscosity is colloquially speaking the thickness of a liquid. So a honey is for example, extremely viscous water is significantly less viscous.  

So a good kind of way of thinking about fountain pen ink is probably that I think water comes in at something like 72. Dyns per centimeter  and pure ethanol is  going to be somewhere in the upper twenties and fountain pen ink lies in between those two extremes, but a little close sort of the ethanol end. So roughly speaking  your surface tension of fountain pen ink should probably be around the same surface tension as some decent bourbon.

John: [00:08:57] We've we finally got it into a [00:09:00] terms that most people at the Pen show after dark can understand. Okay,

Nicole: [00:09:04] That's what I am for.

John: [00:09:06] perfect. So one of the big questions that I think a lot of folks have tossed around over the years is why do fountain pens misbehave on aircraft?

Nicole: [00:09:19] Yeah,  that's a classic problem. And it's one that doesn't just happen with aircraft.  

You and I are here in Colorado and  other folks around here sometimes live up in the mountains and come down with their fountain pens and discover problems going one way or the other with those changes in altitude.

So what happens when you change altitude or when you get an airplane, is that you have a change in the atmospheric pressure. The reason for that is just that it's easier to pressurize the aircraft at a lower pressure on the inside than it is to maintain a high pressure on the inside and the very low atmospheric pressure on the outside when you're flying at 35,000 feet.

The thing [00:10:00] about liquids is they like to flow from areas of high pressure, to areas of low pressure, which you'll definitely remember from your geophysics and that's exactly what happens in your fountain pen. So if you have,  if you have a dead space in your fountain pen and you have an atmospheric pressure that is equivalent to wherever you started before you got on the airplane. And then you go up in the cabin and the pressure drops. Now the pressure outside is lower than the pressure inside your pen and the ink tries to flow out. So you end up getting burping and drop stuck up in your cap. And if you're not careful, you can make a big mess.

John: [00:10:45] Yeah. And I think that. One of the things you were talking about, where if you have like dead spaces in your pen is the reason why so many people emphasize storing your pins in a nib up position, because that [00:11:00] allows that dead space to be on the top of the cartridge or the top of the. Converter or whatever filling system you're using.

And it allows that air to expand up into the nib instead of it pushing your ink into the nib where you're going to have it. If you've got it laid down on its side or nipped down and allowing that air pressure in that dead space to actually push on the ink and create a mess.

Nicole: [00:11:26] true, but remember that probably still have ink that's caught inside the feed. So when that air from the dead space is expanding up into your feed, it's still going to push ink out. 

John: [00:11:38] So why doesn't a fountain pen leak when you hold the nib upside down?

Nicole: [00:11:42] There are situations where it could actually leak. But then you would have a really bad fountain pen ink because the surface tension would be too low. In that case, basically the surface tension of fountain pen ink is tuned so that it flows nicely up into the feed, but it doesn't flow [00:12:00] so freely that it just falls right out as soon as you turn it upside down.

John: [00:12:04] Yeah. And I think that this is where we get into that idea of how, wet a particular fountain pen ink is. Because when you get into broader sized nibs, they tend to not hold  the wetter Inks in as well. And I've, I think everyone has had an occasion with the fatter nibs of having ink just drop out of the pen on you, because it just does not have enough surface tension to retain the ink on the nib.

Nicole: [00:12:34] Yeah, I noticed I relatively recently got a pen with an ebonite feed and a gold nib, and it is crazy wet. Compared to just about any other pen that I'm used to. And I definitely have to be careful about just opening it up and finding ink has splattered all over inside it. And I'm not entirely sure if that [00:13:00] is a result of some jostling when it got carried or if it's just that ebonite is so good at drawing fountain pen ink, that it makes it really easy for it to start spurting.

John: [00:13:14] Yeah. And that actually does bring up a really good point. Can you talk about the differences between that interaction between the fountain pen, ink and like a plastic feed versus an ebonite feed?

Nicole: [00:13:26] 

I don't have specific numbers on how that's going to affect the surface tension, but just from my own experience, it's very clear that fountain pen ink flows much more readily on the ebonite than it does. On the inside of plastic feeds. So clearly if you want to have a really wet writer or you want to keep up with say a flex nib, that's where having that ebonite feed is going to make a really big difference because clearly it is  I guess we would say Inkiphillic.

John: [00:13:57] Yeah. And I think that also, [00:14:00] when you're talking about some of the specialty flexible nib feeds like a flexible nib factory puts out, I think they also include additional channels on those to help encourage the additional flow of ink.

Nicole: [00:14:14] Yeah, I think the additional channels are sometimes also to try and give more capacity near the nib so that you can  smooth out the flow by having more places for it to be essentially waiting for its use.

John: [00:14:32] Yeah. It wasn't like setting it up as a reservoir.

Nicole: [00:14:35] Yeah.

John: [00:14:36] Okay. And actually, I believe there are some spots in the world that they actually still call fountain pens, reservoir pens. So that makes a lot of sense.

Nicole: [00:14:45] I think that's a, that's what they are. That was  the innovation beyond the old dip style pens was that you basically had the inkwell inside. It.

John: [00:14:55] Yep. So  we're talking about inks and that leads into the [00:15:00] question of what is your favorite fountain pen ink.

Nicole: [00:15:03] Oh, that is an incredibly difficult question because I have, and love  many, many, many inks and I think I might be able to choose favorites within each color category, but I would have a really hard time choosing, using an overall favorite ink. I like switching around a lot. I like having a lot of different colors available to me at any given time.

And if you look at my fountain pen companion profile, you will see that I have quite a lot of ink.

John: [00:15:35] Okay, then let's go ahead and let's break it down. Then let's go for your conservative black blue or blue, black ink. And then one from the wild category.  Right? Is that close enough? Or do we have to get closer?

Nicole: [00:15:48] I'm probably just going to choose something. That's off the top of my head. So I, I have currently a permanently inked pen with platinum carbon black. That's  my preferred [00:16:00] waterproof option at the moment.  Also in the black category, I. Inked up some Lamy crystal obsidian a few months ago, and really enjoyed that.  Although it got a little smeary in some of the drawings that I was doing, and I am a real sucker for blue blacks, I would have a very hard time choosing just one, definitely early in  my ink collecting habits. I discovered that I just. Bought up pretty much any blue / black that struck my fancy

John: [00:16:35] That is entirely, your prerogative  as a fountain pen ink collector. So let's go over to the wild side then.  Do you have any particular wild inks that you enjoy?

Nicole: [00:16:46] So I'm on a constant hunt for my perfect orange and I thus have quite a few orange inks in my collection. One of the ones that, that I enjoy for the color a lot [00:17:00] is papier plume. Sazerac though I do find that one is really dry. So I think I'm probably gonna next time, try to add a little bit of a white lightening to it.

I think Eldorado  is pretty nice too. KWZ Eldorado for that kind of color and actually one that. One that I tried recently and thought was really neat, was  Robert Osters, Australis Tea that one is just a really unique color, at least compared to everything else in my collection. I couldn't find anything quite like  it's very like matcha tea colored. And  another one that I've enjoyed a bunch recently is a limited edition that papier plume put out called the blue Heron. That one is also just a really nice, almost blue, gray

John: [00:17:49] Okay. So I want to go back to the Sazerac. So I'm, I've been down to new Orleans a couple of times the Sazerac at least is in terms of a drink is  a [00:18:00] brownish orange. Is that. Standby for the ink as well.

Nicole: [00:18:03] The ink is a little bit more on, on the bright orange side. It goes quite nicely. I find in  

the sailor cocktail series, tequila, sunrise.

John: [00:18:15] Okay. Very good. Yeah, that's a great might as well. well go with cocktail and cocktail on that one.

Nicole: [00:18:20] that was exactly my thought when I decided what to ink that pen up with.

John: [00:18:25] Oh, there you go. So you having ink doesn't do you any good, unless you have paper to write on, do you have a favorite paper?

Nicole: [00:18:34] I am actually. Pretty open to a lot of different papers, depending on what it is that I'm trying to do. I have been, I've been doing things like bullet journaling for literally years now. And I do a lot of that in Leuchtturm. Which is not necessarily the best fountain pen, print, friendly paper, but it [00:19:00] works pretty well.

I am actually just about to finish up an endless notebook with some tamoe river and I've got a rhodia pad here and I have a few Midori pads that I'm going to be trying out and seeing how I like those. So I'm Maybe not equal opportunity at this point on paper, but I'm still exploring my options and have it settled with a one specific favorite

John: [00:19:23] Oh, that'll work. The last one we have here for the ink pen and paper triumphant is, do you have a pen that you find yourself reaching for these days?

Nicole: [00:19:34] So the one that I think I've been reaching for an inking up a lot these days is. Is my first vanishing point, which is the matte black vanishing point. And I resisted getting a vanishing point for quite some time thinking that I didn't really like it. I wasn't sure about the clip. But I got this one and just pretty immediately fell in love.

It's a great [00:20:00] pen to have around just for the quick notes that I tend to write in the course of my daily job. So I like sticking a nice bright ink in there. And otherwise keeping my stealth pen

John: [00:20:13] Okay, I'm going to guess  that's probably a fine nib on it.

Nicole: [00:20:17] I have a fine nib on it. I actually also got a medium nib unit in case I wanted to go a little broader. And I confess that I picked up a second vanishing point late in the year with an extra fine nib. But that one, I think is maybe a little overly dry writing. Maybe I need to put a wetter ink in it.

John: [00:20:36] Yeah, I agree with the wetter ink. Also, I found that the finer nibs also have a harder time with lighter inks. So you've got to go with something darker.

Nicole: [00:20:46] Yeah, I had really good luck with Sailor Manyo, Yomogi when I put it in the fine nibs. So I think I may try that next time in the extra-fine. I think that'll probably work nicely.

John: [00:20:57] Nice. Yeah, sailor's [00:21:00] definitely got some good wet inks. I'm actually writing on a Mnemosyne pad with Sailor Colorado, which is their purple ink and it flows beautifully.

Nicole: [00:21:10] I have that sitting at a cart right now.

John: [00:21:12] There you go. I'll push you along  and penable you on that one.  Can you share one technique with listeners that you think will elevate their snail mail art?

Nicole: [00:21:22] so I'm definitely a beginner at the snail mail art. I'm trying to start getting into it. I've got some rubber stamps then I'm going to start using, but  my go-to at the moment is just a little bit of washi tape to  dress up my envelopes a bit.

John: [00:21:37] Yeah. And actually that's one thing that just had a, an interview and we were talking about all of the different uses for washi tape. And it's amazing how much. You can make your own custom stationary just by laying out a line of washi tape, along a border on a plain piece of paper. So that's really cool.

Nicole: [00:21:58] Yeah, there are some great [00:22:00] washi options out there. Whether I want something fluidsey, or Spacey,

John: [00:22:05] Oh, yeah, absolutely. And one of the things we were talking about, and I just seen it on the Pen addict Slack was one of the, a table of elements, washi tapes that I still haven't bought, but I've got to get it.

Nicole: [00:22:20] classic.

John: [00:22:21] Yep. So are there any artists out there doing amazing work that the stationary lovers need to know about?

Nicole: [00:22:29] so I had to think hard about this one, because a lot of the cool people that I follow are people that have been mentioned already on the podcast. So I'm going to take this in a slightly different direction. And something that I think has a little bit of overlap, at least with people who like.

Vintage things like fountain pens and snail mail is are maps. And my husband actually has the hobby of drawing maps and he's part of an [00:23:00] online community called the cartographers Guild. And there are some supremely awesome artists working in this kind of field of. Often fantastical maps, and many of them do it with with ink and pens very similar to what we like to do in our world.

So I definitely recommend people check out the cartographers Guild and see some of the cool stuff going on there.

John: [00:23:26] That's very cool. And I'm actually going to dig in a little bit deeper on that, just because a couple of episodes back I had Tim Ely on and his specialty is an entire art form of making art books that are basically alien cartography. And he ends up using a lot of made up characters that he calls cribiform.

When you're talking about the folks that are in the cartographers Guild, do any of them resort to [00:24:00] other kinds of script in order to write on the maps?

Nicole: [00:24:05] Yeah. There, there are a wide variety of things, depending on what kind of style the map is. I know some of the ones that my husband has done actually involve things, sort of like, the cribriform where he aims to have characters that look like just somebody scribbling a little note on there, but are not actual recognizable characters from any language that we have.

There are also a number of people who get straight up into calligraphy in terms of labeling maps. I know that there are some artists that my husband likes to follow on there that, that do like full Gothic, medieval calligraphy in the midst of their maps.

John: [00:24:47] Yeah, there you go. That was, those are, I'm sure that there was some beautiful stuff out there. I'll have to make sure we get some links into the show notes for these folks. So that leads us to our last question. What is your favorite purchase [00:25:00] stationery or not in the last six months?

Nicole: [00:25:03] probably that a pilot vanishing point, that one has really stuck with me. I will confess to way too much retail therapy in late 2020, but I get the feeling that's probably true for a lot of us.

John: [00:25:17] Yeah, absolutely. That's not An isolated incident for anybody for 20, 20, 20, 20 kind of sucked and all of us needed a little, Hitch in our giddy-up to get through that whole thing. So thank you very much, Nicole, for being on stationery orbit with us tonight.

 If you're interested in seeing more of Nicole's work, you can find her on the internet at the following places. You can find her on Instagram at F Y fluid dynamics, and you can also follow her fountain pen and ink work at aerognome on Instagram, you can find amazing articles that will expand your knowledge of the world of fluid dynamics at her website  FY fluid dynamics.com.