An alternative look at ink wetness

[arcfide]

Very good stuff, and I look on with interest. As more data comes up, and as the ways of measuring wetness and determining what constitutes wet improve, I'll be very interested to see how things pan out. 

 

I think the difference between an Ink Guy and these tests are that they are targeting different things. Here the goal is to identify potential correlations between an ink's properties and the "glistening pool of ink" effect, here called wetness. That is, it's about the wetness of an ink on the page and at the very last moment on the nib. An Ink Guy's wetness model is meant, firstly, to be easy to do, but secondly, to identify how well an ink may or may not flow through a pen, that is, the wetness in the pen itself, rather than particularly on the paper. 

 

Just as two great examples, Sailor Black is considered a very wet ink from "An Ink Guy's" measure, as is Parker Black, and they both flow exceptionally well in pens, without clogging or otherwise having bubbles in the converter. On the other hand, inks like Perle Noire or other Jacques Herbin inks are often identified as being dry, and my own experience backs this up, with some of my black Herbin inks being more susceptible to "sticking" in the converter, undoubtedly tied to surface tension and viscosity. However, on the page, the effect is reversed, and many people note how Herbin inks glisten well on the page and leave a clean, sometimes lubricated feeling line coming off the nib. Whereas the Sailor and Parker Black inks might lay flatter on the page and therefore give less of a lubricated feeling depending on the nib and pen. In these cases, the Sailor/Parker inks seem wet in the pen, while the Perle Noire and other "thick" Herbin inks seem wet on the page. 

[A Smug Dill]

On 5/23/2021 at 4:23 PM, InesF said:

And now I like to present an alternative view at ink wetness.

 

I'm in complete awe of the amount of thought, rigour and effort you've put into this!

 

Thank you very much for sharing the fruits of your research and experimentation.

[mizgeorge]

Ditto to the above - brava!!

 

It may take me a while to actually understand it all though

[InesF]

12 hours ago, DrDebG said:

Fascinating and time consuming study!  Thank you for taking the time to do this.  It sounds like it will be a multi-year project.  Are you going to use the results to write a doctoral thesis?  😁

 

After you have nailed down your technique and satisfied yourself with consistent, replicative results, you may want to expand the study to include different "fountain pen friendly" papers (i.e. Tomoe River, Clairfontaine, Cosmo Air Light, etc.)

 

Thank you again for doing this.  I look forward to see more of your results. 

Thank you!

I thought a while about the paper types and did some minor experiments before the main test. Maybe other paper types will follow, maybe not. My ultimate goal is to find the causalities (and to generate this one-and-only-universal-formula-that-expalins-it-all) and it looks like, that surface tension, viscosity and paper surface hydrophily is all thats needed.

Yes, it is a long term project that will keep me busy for a good while. 

[InesF]

11 hours ago, sansenri said:

Impressive work.

The measurements on surface tension really do shed a light on some ink's similarities.

 

The Extran seems to be the next best cure for reluctant converters...

Thank you!

Indeed, i did cure some nasty converters with Extran. Acrylics, most plastic types (including PE, PP, ABS, PS, etc.), steel, precious metals withstand Extran. Unfortunately ebonite does not! That's why I do not recommend to use it in routine cleaning!

However, household dishwasher soap, especially if it is skin friendly or suppresses formation of 'water drops' on glass or such are not the best choice for fountain pen cleaning, as they leave some residues on the surfaces that interact with the ink. Such residues may be responsible for the bad wetability of 'cleaned' converters...

[InesF]

11 hours ago, inkstainedruth said:

What an amazing amount of work you've done, InesF.

The only concern I have is in the use of gum arabic, because a lot of people on here warn against its use (and inks containing it such as India ink) for fountain pens, because it can gum up a feed something awful.

And of course pens can be inconsistent, even between brands/models/nibs.

Ruth Morrisson aka inkstainedruth

Thank you!

Gum Arabic can be very nasty when dried inside an ink capillary (in the feed) but is generally more on the harmless side. It is well water soluble and - after some extended soaking time - it will come out again. That's the difference to water resistant inks (containing protein glue or acrylic medium) which cannot be removed when dried somewhere inside.

[InesF]

9 hours ago, arcfide said:

Very good stuff, and I look on with interest. As more data comes up, and as the ways of measuring wetness and determining what constitutes wet improve, I'll be very interested to see how things pan out. 

 

I think the difference between an Ink Guy and these tests are that they are targeting different things. Here the goal is to identify potential correlations between an ink's properties and the "glistening pool of ink" effect, here called wetness. That is, it's about the wetness of an ink on the page and at the very last moment on the nib. An Ink Guy's wetness model is meant, firstly, to be easy to do, but secondly, to identify how well an ink may or may not flow through a pen, that is, the wetness in the pen itself, rather than particularly on the paper. 

 

Just as two great examples, Sailor Black is considered a very wet ink from "An Ink Guy's" measure, as is Parker Black, and they both flow exceptionally well in pens, without clogging or otherwise having bubbles in the converter. On the other hand, inks like Perle Noire or other Jacques Herbin inks are often identified as being dry, and my own experience backs this up, with some of my black Herbin inks being more susceptible to "sticking" in the converter, undoubtedly tied to surface tension and viscosity. However, on the page, the effect is reversed, and many people note how Herbin inks glisten well on the page and leave a clean, sometimes lubricated feeling line coming off the nib. Whereas the Sailor and Parker Black inks might lay flatter on the page and therefore give less of a lubricated feeling depending on the nib and pen. In these cases, the Sailor/Parker inks seem wet in the pen, while the Perle Noire and other "thick" Herbin inks seem wet on the page. 

Hi arcfide, thank you for the detailed comment.

Sure, more data will come. I'm also looking forward to ideas, theories and comments that may help me to focus on the 'important' things.

The Ink Guy is not wrong. But one conclusion out of it all is wrong: if the ink flow of a pen is limited, you recognise a behaviour that is different from wet or dry writing! That is a major thing!

Imagine: if you draw a line that would require more ink output than is possible to pass through the ink channels, you will see a wet start (the feed is saturated) with rapidly decreasing ink amount until, probably, you experience some skipping.

And the test proves that the pens are not in limited flow, although laying down different, small amounts of ink.

see also: https://www.fountainpennetwork.com/forum/topic/360005-diagnosing-ink-starvation-and-nib-drying/#comments

 

[InesF]

8 hours ago, A Smug Dill said:

 

I'm in complete awe of the amount of thought, rigour and effort you've put into this!

 

Thank you very much for sharing the fruits of your research and experimentation.

Thank you!

More data will come (over the month) until enough is collected to run a principal component analysis.

[Ergative]

Just now, InesF said:

Thank you!

More data will come (over the month) until enough is collected to run a principal component analysis.

 

I would be fascinated to see what comes out of the PCA!

[InesF]

7 hours ago, mizgeorge said:

Ditto to the above - brava!!

 

It may take me a while to actually understand it all though

Thank you!

Take your time, my updates will come slowly. Have a cup of tea, meanwhile.

Next thing will be the updated and corrected drawing of the 'ink-wetness-theory-in-images'. (I made a capital error in version 1 and need to redraw it)

[7is]

10 hours ago, arcfide said:

...In these cases, the Sailor/Parker inks seem wet in the pen, while the Perle Noire and other "thick" Herbin inks seem wet on the page. 

I don't know these particular inks, except of Perle Noire, but from my experience with other inks it seems to be true that so called dry inks leave 'wetter' lines (and for longer) on the same type of paper. I remember that someone on the forums explained before how surface tension acts against water evaporation. I admit that my assumption is that dry inks always have significantly higher surface tension.

[InesF]

(for any reason, I cannot edit my first post)

Here the promised graphical ink wetness theory:

 

The following is a hypothesis!

The formation of the moving ink film (h2 and h1) depends more on viscosity than on surface tension. The width of the ink line depends instantly more on surface tension which also supports feathering and spreading, but those are countered by higher viscosity of the ink.

However, the paper surface has a bigger effect than any effects deriving from ink properties.

 

My first attempt on testing ink spreading, by applying 10 and 25 µL ink on a single spot showed clearly that a not absorbent paper (Kyome letter pad in the front) does not support spreading while an absorbent paper (noname notepad in the middle) lets the ink spread. The ink drops on the Kyome paper dried over night to spots of the same size - in other words: zero spreading! It is not surprising that an ink line is more narrow on good paper and appears more wet compared to the line on absorbent paper.

The drops look very similar, independent from ink surface tension and from viscosity!

(remark: the 10 sec spot was my attempt to measure ink spreading when the tip of the nib is held for 10 seconds at one place. You can imagine the outcome)

[amberleadavis]

@InesF

 

This is WONDERFUL! Thank you!

 

I have added this thread to the Start Here List.

I have also moved it to the Comparison Section.

 

Performance and Properties
Inky T O D - Lubricating Inks
https://www.fountainpennetwork.com/forum/index.php/topic/265842-inky-t-o-d-lubricating-inks/
Inky T O D - What Are Dry Inks?
https://www.fountainpennetwork.com/forum/index.php/topic/265786-inky-t-o-d-what-are-dry-inks/
Inky T O D - What Are Wet Inks?
https://www.fountainpennetwork.com/forum/index.php/topic/265785-inky-t-o-d-what-are-wet-inks/

An Alternative Look at Ink Wetness

https://www.fountainpennetwork.com/forum/topic/330981-inky-t-o-d-making-inks-drier-dryer-drying-additives/

[sansenri]

On 5/25/2021 at 10:28 AM, InesF said:

Thank you!

Indeed, i did cure some nasty converters with Extran. Acrylics, most plastic types (including PE, PP, ABS, PS, etc.), steel, precious metals withstand Extran. Unfortunately ebonite does not! That's why I do not recommend to use it in routine cleaning!

However, household dishwasher soap, especially if it is skin friendly or suppresses formation of 'water drops' on glass or such are not the best choice for fountain pen cleaning, as they leave some residues on the surfaces that interact with the ink. Such residues may be responsible for the bad wetability of 'cleaned' converters...

 

Yes, I was thinking of treating exclusively the converters...

I have done so on some nasty converters that would have ink cling to the walls inside of them instead of flow to the nib, with some grease remover, like Cillit Bang or similar. That has often worked.

I never wash pens with anything else except water...

[InesF]

Here is the data update from this weeks measurements:

 

As already mentioned earlier, I will stop doing the ink consumption measurement with the Pelikan M600 - it is redundant data.

The new consumption data with two identical inks (deAtramentis Aubergine) with and without Gum Arabic demonstrate, once again, that surface tension is way more important than viscosity. However, at a viscosity of 1.23 mPa*s both pens ran into ink starvation at ca. 10 g ink/km on the photo paper (and the Waterman most probably also on the absorbent paper).

 

On Thursday I have received my very first bottle of Colorverse ink. What a surprise! - the inks come with a data sheet with surface tensions and pH-value for all inks of the same series!

 

Unfortunately, I can't do new measurements in the coming week, so the next update is to expect in two weeks from now.

[alexwi]

On 5/23/2021 at 2:23 AM, InesF said:

Currently, I can‘t measure line width with sufficient precision

 

Hi,

 

Very impressive! Can't help but envy the amount of time you have to dedicate to quantifying qualities that, until now have been limited to relative, often subjective, observation.

 

If you scan the line tests at a sufficiently high resolution, you can measure them quite precisely with gimp or photoshop, either by directly measuring a line or reading the histogram of a 1 cm^2 area and some math, which should give you an average.

 

[Frank C]

This is a very interesting discussion. I minored in biochemistry at university, so I appreciate the scientific aspects of fountain pens and ink. 

 

I looked up the SDS (Safety Data Sheet) on Extran®  Alkaline: https://www.emdmillipore.com/US/en/product/msds/MDA_CHEM-107555?Origin=PDP 

It is a very serious cleaning solution. The chemical structure of one of the active components is: 

The other active ingredient is Sodium Hydroxide. The solution has a pH of 12.94. Wow! 

 

I have a related question. There is an ongoing discussion on another thread: The Meisterstück 149 Calligraphy Appreciation Thread, about the best ink to use with a flexible nib. Surface tension is what gets ink to spread on the tines of a flexed nib. I would guess that lower viscosity helps the ink to spread on the tines better. I would appreciate any comments you have. 

[a_writer]

@InesF thank you so much for doing this work! 😃  I'm definitely subscribing to this thread and will continue to read it with interest.  Question from a non-chemist: Why isn't specific gravity/relative density relevant?

[InesF]

On 6/5/2021 at 6:21 AM, a_writer said:

@InesF thank you so much for doing this work! 😃  I'm definitely subscribing to this thread and will continue to read it with interest.  Question from a non-chemist: Why isn't specific gravity/relative density relevant?

Hi a_writer.

Gravity, density, viscosity and, to a certain extent, width of the ink channel are properties and conditions that will somehow limit ink flow. If you write with a pen which can't deliver as much inks as necessary, you will see a wet start of your lines with decreasing ink amounts delivered over time. Your lines will become more dry the more you write. This is a sign of ink starvation and may be a good reason to make a pen service or to choose a different ink for your pen.

But such a behavior is not a synonym for ink wetness.

 

A hypothetical situation: if the ink channels in your pen are so wide that A LOT of ink is running out as soon as the tip touches the paper, A LOT of ink will run out independent from viscosity but it will spread further from the line (from the touching point) the lower the surface tension and the lower the viscosity is. But: if the channels are too narrow, the pen will suffer from ink starvation. The ideal is to never have a limited flow but, regardless, have no spreading (and no feathering and no bleeding, etc.). However, the wetability and the absorbence of the paper has more influence on spreading than any of the ink properties.

 

So far, the test showed that no pen was in ink starvation when drawing the lines on absorbent and on ink friendly paper. While less ink was delivered on the friendly paper the lines looked more wet there!

[Sholom]

Wow! Sorry I'm coming to this late and no longer have access to a lab myself, but I don't think I would have had the patience to do this amazing work. Just one thought: surface tension in this context is really a proxy (generally a pretty good one) for interfacial tension, specifically between ink and nib and ink and paper.  Since paper is porous, measuring ink interfacial tension with it may well be impossible. Given the wide range of paper coatings (yes fountain pen-friendly paper is coated–just try writing on filter paper to see what effect the paper coating has), interfacial tension could explain some observed differences between what people report for ink behaviour with the same ink and similar nibs. Similarly, a possible difference between steel and gold nibs may be some subtle differences in interfacial tension between nib and ink. That may be easier to measure (e.g. contact angles). Just thinking out loud and thanks again for these measurements.