Inconsistent ink flow in new pen

[jrdavis]

My new pen has inconsistent ink flow by which I mean that there is more ink produced when I begin writing, and that as I write the ink flow diminishes.  But, as I continue to write more, the ink flow increases for several words, until it slows down again.  There is no frank skipping.  The ink flow decreases as I write, then increases, then decreases, then increases.  This is unlike the performance of all my other pens.  I've attached a photo where I have marked portions with increased flow.  The ink is Diamine Ancient Copper written on Tomoe River paper.  I have tried flushing the pen once.  The pen is a piston filler with ebonite feed.

 

What is the problem?

 

What is the remedy?

 

Am I being too fussy.

[arcfide]

Based on this look, I would conclude that what you're seeing is the natural variance in flow that occurs as a feed becomes more and less saturated as the pressure equalizes inside of the ink reservoir. In a pen, the ink doesn't leave the reservoir consistently, but instead, in all pens, it does so in spurts, with points where air flows up into the reservoir to equalize pressure, in the same way that a bottle turned fully upside down will release liquid inconsistently as it goes through cycles of air pressure equalization. 

 

If you have a wet pen with high flow and the feed readily saturates with a large amount of ink all at once, then you can get a very wet line followed by a progressively drier line until another air bubble flows into the ink reservoir and a large amount of ink subsequently resaturates the feed. 

 

Whether you are able to detect this change depends on the wetness of the nib, the level of flow control that comes from the feed, and the wetness of the ink, as well as how much ink is actually in the reservoir (this behavior will change depending on whether you have more or less air in the reservoir), and the absorbency of the paper. 

 

All of my pens across a range of makes exhibit this behavior to some degree, but some of them are barely detectable under normal use, and some are much more detectable. 

 

You can probably see a difference by changing the flow of the nib as well as playing with the ink and paper. 

[jrdavis]

arcfide, thank you.  That is very clear and helpful information.  I have been using fountain pens regularly for only a year and did not appreciate how the air enters the ink reservoir only in bubbles rather than in an evenly continuous manner.

[arcfide]

3 hours ago, jrdavis said:

I have been using fountain pens regularly for only a year and did not appreciate how the air enters the ink reservoir only in bubbles rather than in an evenly continuous manner.

 

If you would like to see this in action and get a feeling for how it can work and the rates involved, find a wet pen of yours with either a clear body and reservoir or a cartridge/converter pen that you can observe with the barrel off. From there, create a thick layer of absorbent paper towels or the like, and touch the nib to the paper to let the paper begin to absorb a rapid amount of ink very quickly. You should be able to see the bubbles in the ink forming as the ink flows out of the converter, especially if you use a lighter ink. I believe surface tension affects how readily a bubble pops in the ink, and so I think that will affect the rate at which the interchange happens. 

 

It's worth also noting that while all feeds do this, some are much more "controlled" than others. Ebonite feeds, IME, tend to be harder to design to sophisticated levels of control, meaning that to counteract ink starvation, they seem to run relatively wet as a rule. With some of my pens, they are so wet that the ink flows out so quickly so as to mask the variation in ink. Likewise, in very carefully designed and controlled feeds, which I find run either wet or dry, such as with Lamy and Platinum, depending on the nib tuning, I find that the control is usually consistent enough that the only time you really notice the difference is on the first few lines of writing where things have had a time to settle, and then afterwards, the "writing equilibrium" sets in and things are pretty even. However, on many other feeds that I've used, this isn't the case. Platinum's Music nib, for instance, has its own special feed to keep up with how wet it is. Because the Music nib spreads out ink more, while also consuming a lot more ink than a typical single slit stub, as well as the wet tuning on the feed, I find that these Music nibs demonstrate the same effect that you see above if I use medium-wet to drier inks, such as Platinum's Blue Black ink, or especially something like Diamine Registrar's. However, with inks that are on the wetter side, the difference is less noticeable. I'm partly convinced this is just due to the sheer volume of ink demanded of these pens out of the relatively small nipple in the #3776 design. On the other hand, I have a BB feed and nib (custom ground to formal italic) from Platinum which uses their "new" feed specifically designed for B and BB nibs, and that pen has very consistent ink flow, even though it isn't gushing wet, however, the ink demand from a single slit formal italic isn't nearly as high as from the double slit music nib, either. I also have a Sailor KOP nib (relatively large, big feed) that only has a B nib on it, and the combination of a very large, expansive feed with a large nib but a relatively small tip size and Sailor's very wet inks seems to create a situation in which I notice less variation archs. The same goes for Platinum's Medium metalic nibs from Preppys and Procyons, which all don't gush in the same way that my music nibs do, but have a rather controlled flow, since I don't think the demand on ink is as high. 

 

All this to say that there are lots of different ways you can play with this effect. Some people find it nice, because they like the extra shading that they get from line to line, but others want something more consistent. My approach is usually to make the pens so wet that the ebbs and flows don't matter, but that isn't a desirable approach for others, so you'll want to find your own preference. 

[jrdavis]

Dear arcfide, thank you again for your message.  The details are enormously helpful, both to my understanding of how fountain pen performance is affected by different variables, and to my enjoyment of applying ink to paper.  I sincerely appreciate your very thoughtful response, John

[dipper]

On 9/2/2022 at 1:13 AM, arcfide said:

...... this behavior will change depending on whether you have more or less air in the reservoir ......

 

Thanks for the beautifully clear explanations.

 

In theory, when the pen is nearly full of ink and the air space in the reservoir is very small then the wetness cycling will happen more rapidly. ( Ink leaving the reservoir causes a greater drop in pressure as the small air space expands. )

When the pen is nearly empty and the air space in the reservoir is larger then the cycling is slower. ( More volume expansion of the larger air space is needed before the pressure will drop far enough to "glug" in the next air bubble. )

 

I like to think of the difference between pulling on a short piece of elastic band, compared with pulling on a longer length of the same elastic band. The air inside the pen is being stretched, like the elastic band.

 

One change that can disrupt the regular cycling of wetness is how we might wave the pen around during use. This is especially so in a piston filler where the generous reservoir diameter allows the ink to slosh around more readily than in a narrow cartridge or converter.

 

On the rare occasions when I am bothered by gradually reducing wetness, as described by @jrdavis, I will tilt the pen to be nib pointing upwards briefly to restore full wetness.

If using a piston filler pen that tilt-up-and-then-carry-on trick usually works instantly. It is probably happening all the time anyway given my frequent errr.. "dynamic" style of pen flourishing!

But if using a converter filler pen, or a slim cartridge, a little more encouragement is needed to make the ink fall away from the feed and allow the pen to draw in a breath of air. A gentle tap with a fingertip may be enough.

[jrdavis]

Most excellently helpful.  Thank you, dipper.

[Maurizio]

On 9/2/2022 at 12:34 AM, arcfide said:

My approach is usually to make the pens so wet that the ebbs and flows don't matter, but that isn't a desirable approach for others, so you'll want to find your own preference. 

 

You could make your ink wetter, that is, increase the rate and volume of the ink’s flow, by adding vegetable glycerin to your ink. I add glycerin to all of my inks except Platinum Carbon Black because I use that as a waterproof ink for watercolor painting and I learned the hard way that the glycerin will smear if water is applied with a brush. But glycerin-enhanced inks won’t smear after drying under normal conditions.

 

If you decide to try this, be careful. You must add the glycerin in tiny amounts. Rather than a whole drop with an eyedropper, i have learned to use a toothpick. I dip the toothpick in the glycerin to get one small drop on the end of the toothpick. Add one of these drops, shake the ink bottle, and test. If the ink is still not wet enough for you, you can keep adding toothpick drops until you like how wet the ink is. But do it carefully and incrementally or you’ll end up with ink too wet to stay in the pen. 

 

One other caveat: adding glycerin does increase the dry time of the ink, so, if you brush your hand or finger across a recently laid glycerin-enhanced ink line, it will likely smear. The glycerin-enhanced ink will dry - as long as you have not added an excessive amount of glycerin - it will just take longer, maybe 60 seconds instead of 20. 

 

 

[jrdavis]

Very helpful suggestion, Maurizio.  Thanks!