An alternative look at ink wetness

[thott]

  On 8/27/2021 at 12:43 PM, InesF said:

A quick 'no-new-data' update.

 

I was sure having read a very good explanation earlier about why surface tension is the most important fountain pen ink property. But I lost the link and was unable to retrieve it until today.

It is Ravens March Fountain Pens site. You find the essence in paragraph 3 of the 'capillary action' chapter.

 

Combined with Amadeus W's site about fountain pen construction (it's an excellent read, I strongly recommend to read it all!), the pen-ink-paper-wetness-theory goes forward, step by step towards ultimate enlightenment.

 

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A very important point for the capillary actions is also the wettability of the nib material.

E.g. Palladium has a better wettability as Gold. May be this is also a reason why the former 

Visconti Palladium nibs are extremely wet.

That means the ink will flow over a Palladium surface more readily than over a Gold surface, 

which has a less wettability. 

 

Thomas

[LizEF]

  On 8/27/2021 at 12:56 PM, thott said:

A very important point for the capillary actions is also the wettability of the nib material.

E.g. Palladium has a better wettability as Gold. May be this is also a reason why the former 

Visconti Palladium nibs are extremely wet.

That means the ink will flow over a Palladium surface more readily than over a Gold surface, 

which has a less wettability.

 

Thomas

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Oh, that's interesting.  We all know that a person's experience will be unique because each of us has a different pen (even if they're the same model, manufacturing tolerances seem to be larger than with, for example, the dreaded ballpoint).  But your addition could further explain differences in inky perception between users.  We have so very many variables already - ink, paper, nib, feed, (I suspect environmental properties like temperature and humidity) - and now we need to add the nib material.  Off hand, I can think of these:

• Stainless steel
• Titanium
• Palladium
• Gold (is gold-plated different?)
• Rose-gold (is plated different?)
• Various K of gold
• Rhodium-plated (does the underlying metal matter?)
• However black nibs are made (I suspect multiple methods for this, but I'm not sure - some seem plated, others seem "blued")
• I'm probably missing some

Whee!

[LizEF]

  On 8/27/2021 at 12:43 PM, InesF said:

the pen-ink-paper-wetness-theory goes forward, step by step towards ultimate enlightenment.

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[InesF]

  On 8/27/2021 at 12:56 PM, thott said:

A very important point for the capillary actions is also the wettability of the nib material.

E.g. Palladium has a better wettability as Gold. May be this is also a reason why the former 

Visconti Palladium nibs are extremely wet.

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Thank you @thott, I fully agree about different wetabilities of different metals. The resulting wetness is then a mix with other parameters (geometry, thickness, stiffness, etc.).

 

  On 8/27/2021 at 1:49 PM, LizEF said:

Oh, that's interesting.  We all know that a person's experience will be unique because each of us has a different pen (even if they're the same model, manufacturing tolerances seem to be larger than with, for example, the dreaded ballpoint).  But your addition could further explain differences in inky perception between users.  We have so very many variables already - ink, paper, nib, feed, (I suspect environmental properties like temperature and humidity) - and now we need to add the nib material. 

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Indeed, @LizEF, there are so many variables in this equation - and only one part will be easy: the interaction is with the surface not with the material below (as long as it is not in contact).

 

Relying on free available data (e.g.: http://www.uskino.com/articleshow_113.html), not only the material main component but also other metals of an alloy (or impurity) do influence the wetability. In this table no wetability for palladium is provided, but you see that pure, clean gold has the best wetability and typical (impure) gold has a low wetability.

But consider: the ink will flow through the slit (and should not be flow limited there) but is in contact with the tipping alloy (not with the nib body!) when released onto the paper.

The suggestion for the enthusiast: keep your nibs clean to keep them reliable! 😓

 

And finally, roughness of the metal surface will have an even bigger influence on wetability (Kubiak et.al, Wear 271 (2011), http://dx.doi.org/10.1016/j.wear.2010.03.029).

 

I'm not sure which one would be solved first, either the great universal theory of the Universe or the great universal theory of ink wetness.

👩‍🎓

[LizEF]

  On 8/31/2021 at 9:49 AM, InesF said:

But consider: the ink will flow through the slit (and should not be flow limited there) but is in contact with the tipping alloy (not with the nib body!) when released onto the paper.

The suggestion for the enthusiast: keep your nibs clean to keep them reliable! 😓

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D'oh!  Should have thunk of that!  I wonder if slits get coated / plated, or if they're cut after that process and therefore represent the normal metal.  I know from visual inspection that they aren't as smooth as the rest of the nib surface (at least, not normally).

 

  On 8/31/2021 at 9:49 AM, InesF said:

And finally, roughness of the metal surface will have an even bigger influence on wetability (Kubiak et.al, Wear 271 (2011), http://dx.doi.org/10.1016/j.wear.2010.03.029).

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Roughness was brought up on reddit when someone was wondering about why titanium nibs seem to write so wet.  (Of course, I pointed them to this thread for reference. )

 

  On 8/31/2021 at 9:49 AM, InesF said:

I'm not sure which one would be solved first, either the great universal theory of the Universe or the great universal theory of ink wetness.

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Front cover of Physics Monthly: Universe Solved! Ink flow still a mystery.

 

Thank you so much for the links and on-going education!  You are a fount of knowledge.

[InesF]

  On 8/31/2021 at 1:44 PM, LizEF said:

Front cover of Physics Monthly: Universe Solved! Ink flow still a mystery.

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Ha, ha! I'm waiting for this! 

[InesF]

Todays update with both data tables, the extended and the short.

 

There are now 54 inks measured for three properties each and 24 of them for their ink consumption/delivery with two different pens both on two different paper types. Progress is still there but as the data set increased, the new data have less influence on the correlation equation. However, outliers become a bit better detectable.

 

A high pH-value makes inks with low surface tension drier while the pH-value is of less importance for ink wetness when it has a high surface tension. That's some new outcome to think about.

 

And here the short table with inks sorted in ascending surface tension:

I will try to get the missing Pelikan 4001 inks (green, violet, turquoise) to have the full basic set and there are still three more Diamine inks waiting for shipment. Besides that, not much more inks are on my wishlist.

 

As always: comments, corrections, new hypothesis etc. are highly welcome and, for sure, if you can find the Grand Universal Ink Wetness Theory (GUIWT), please share it with the community! 

 

Next update in 2-3 weeks. Have a good time!

[Frank C]

Thanks for posting this. I realize how much work this represents. 

[LizEF]

  On 9/4/2021 at 6:26 AM, InesF said:

There are now 54 inks measured for three properties each and 24 of them for their ink consumption/delivery with two different pens both on two different paper types. Progress is still there but as the data set increased, the new data have less influence on the correlation equation. However, outliers become a bit better detectable.

 

A high pH-value makes inks with low surface tension drier while the pH-value is of less importance for ink wetness when it has a high surface tension. That's some new outcome to think about.

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Thanks for the update!  I too appreciate all the hard work you're doing.

 

The new data my not influence correlation, but who knows what other revelations (like the one in the second paragraph) they may offer.  The surface tension correlation with flow seems obvious, but I'm having a hard time figuring out why high pH "restrains" the low surface tension ink.  The back of my brain will have to ponder that for a while.   I want to say there must be some reaction with paper or air or even the feed or nib (because something has to be reacting to otherthing, and there are only so many things...), but I can't go further than that.

[InesF]

  On 9/4/2021 at 3:55 PM, Frank C said:

Thanks for posting this. I realize how much work this represents. 

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Thank you, @Frank C.

Curiosity drives me forward....

[InesF]

  On 9/4/2021 at 5:38 PM, LizEF said:

Thanks for the update!  I too appreciate all the hard work you're doing.

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Thank you @LizEF!

 

  On 9/4/2021 at 5:38 PM, LizEF said:

The new data my not influence correlation, but who knows what other revelations (like the one in the second paragraph) they may offer.  The surface tension correlation with flow seems obvious, but I'm having a hard time figuring out why high pH "restrains" the low surface tension ink.  The back of my brain will have to ponder that for a while.   I want to say there must be some reaction with paper or air or even the feed or nib (because something has to be reacting to otherthing, and there are only so many things...), but I can't go further than that.

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It is a form of reaction with either the cellulose or with any one of the paper coatings and additives. Among the range of starch, limestone (and other minerals) and diverse polymers, especially the minerals can chemically interact with acids and alkali, while the polymers are hard to predict but I guess they can physically interact with the polarity of the ink. And the polarity is influenced by the pH-value and by the overall content of mineral salts, alcohols and hydrophobic dies.

Yes, this puzzle causes quite a headache.

 

Since a while I'm looking for a conductivity meter .... still hesitating, as the useful instruments are a bit expensive.

It is not the end of all days, yet.

[LizEF]

  On 9/7/2021 at 12:21 PM, InesF said:

It is a form of reaction with either the cellulose or with any one of the paper coatings and additives. Among the range of starch, limestone (and other minerals) and diverse polymers, especially the minerals can chemically interact with acids and alkali, while the polymers are hard to predict but I guess they can physically interact with the polarity of the ink. And the polarity is influenced by the pH-value and by the overall content of mineral salts, alcohols and hydrophobic dies.

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   Thank you for the explanation.  Things just get more and more interesting as you proceed!

 

  On 9/7/2021 at 12:21 PM, InesF said:

Yes, this puzzle causes quite a headache.

 

Since a while I'm looking for a conductivity meter .... still hesitating, as the useful instruments are a bit expensive.

It is not the end of all days, yet.

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Nightly News Opener: World Ends! People awoke this morning to discover there will be no more days.  In other news, ink flow is still a mystery and causing InesF headaches once again.

[InesF]

A smaller intermediate update today. Meanwhile 60 inks are measured for three of their properties and 27 of them for delivery/consumption with two pens each on two different paper types.

 

Here the condensed ink properties table:

 

By chance I recognised a strange development during the ink consumption measurement: Last week I measured an ink I had used already some weeks before (yes, I took notes, but changed my mind in the last second and changed it wrongly. Life and science, both happen when you are busy doing other things). And so I got the chance to recognise that both pens now deliver ca. 15% less ink at the same line length. Line width also decreased. Oh no, a riddle!

 

So I inspected the nibs with the microscope and found them exceptionally well polished where they touch the paper and have, if any, then tiny small scratches in only one direction. Riddle solved! I draw straight lines along a ruler holding the pens (best possible) always at the same angel.

I guess the tips of both nibs changed and will further change over test time. This is bad news as it will bias the measurements and I feel unable to bring the tips back to their original status (they were both brand new).

In other words: I will continue the measurements but will check from time to time how far the 'wear' of the nibs has gone. No rule for now, but when I feel it became too much, I will stop this series and make the big statistics with what I have got so far.

The end is near.

 

Last week I found a conductivity meter for an affordable price and ordered it. Unfortunately the seller could not give me a fixed delivery date. As soon as it arrives I will measure all my inks for conductivity.

 

That's all for this time, next update in ca. 2-3 weeks.

Have a good time, stay healthy!

[LizEF]

  On 9/19/2021 at 6:06 PM, InesF said:

The end is near.

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[InesF]

  On 9/19/2021 at 6:22 PM, LizEF said:

 

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@LizEF, that's simply perfect! You got my face expression better than real life.

If you allow, I will print it and put it at my office wall, in front of me, always remembering me about the limited time left.

 

[LizEF]

  On 9/20/2021 at 6:51 AM, InesF said:

@LizEF, that's simply perfect! You got my face expression better than real life.

If you allow, I will print it and put it at my office wall, in front of me, always remembering me about the limited time left.

 

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Print away!  (I wasn't sure how familiar you might be with "street-corner preachers" - I'm not even sure if they're that common a thing in the US anymore (don't really go to city street corners), but I hoped you would get the reference.)

 

  On 9/20/2021 at 6:51 AM, InesF said:

always remembering me about the limited time left.

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A good thing for all of us to remember!

[InesF]

Today, again, a smaller update with some new data and a surprise.

 

Still, 60 inks have been measured for three of their properties, meanwhile 33 of them are measured for consumption/delivery with two pens on two different paper types, each. Meanwhile the correlation function does change little with the new data, but the correlation coefficients had improved so that outliers became much better visible.

 

Task of the next two weeks will be to repeat the delivery measurements of those inks which appear to be outliers. This should allow to identify them either as 'inks with irregular behavior' or as measurement errors.

 

The diagram shows ink consumption for one fountain pen only (Waterman Perspective M), probable outliers marked with purple circles.

 

 

Here is the full data set with both fountain pens (W. Perspective M and Cross Botanica M):

 

 

A first PCA did show some nice dependencies, however, I feel disturbed by the outliers and like to wait with pre-final conclusions until

a) the outliers are either confirmed or corrected

and

b) the electrical conductivity measurement is complete!

 

b is the surprise! The conductivity meter has arrived! A nice little instrument that needs no more than 120 µL ink for the measurement. It is not of highest quality, but does its job very well - a new toy for InesF! 

 

Next update (maybe a big update?) in ca. 2-3 weeks.

Have a good time!

[LizEF]

  On 10/9/2021 at 9:53 AM, InesF said:

The conductivity meter has arrived! ... a new toy for InesF!

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Congratulations!  I hope you enjoy your new toy.

 

Thanks for the update!

[dipper]

Previously in this (brilliant) thread .....

 

Measurements of pH values of inks showed some link with wetness, but raised the puzzling question: How can that be?

 

Found this today. Could be relevant, if any amphoteric surfacants are present in ink or in paper?

"The pH of any given solution will determine how the amphoteric surfactants react. In acidic solutions, the amphoteric surfactants become positively charged and behave similarly to cationic surfactants. In alkaline solutions, they develop a negative charge, similar to anionic surfactants."

 

The full page link is

www.ipcol.com/blog/an-easy-guide-to-understanding-surfactants/

 

[InesF]

Thank you @dipper!

 

Indeed pH and polarity of an ink changes its interference with the paper. There we need to consider, a paper consists not only of cellulose but also of starch, lime, proteins (whey, gelatine), pigments, etc. and maybe some synthetic polymers.

For reasons of material recycling, I hope there are no intentionally added polymers - but this is another story.

 

The ink producer looks at the pH range where the dye (or mixture of dies) has the highest chemical stability. This pH value is adjusted and all other needs are customised around that. That means: a surfactant is chosen that works best under the given conditions. To stabilise the whole mixture, the amount of detergent and the amount of anti-foam (= anti detergent = lubricant) is added. Some recipes do not only follow a material need, it can be more a fulfilling of sensual expectations as well.

 

Finally, you get an ink with certain properties which are the result of the 'needs', such as: surface tension, viscosity, density, pH-value, electrical conductivity, polarity, etc.

 

When the ink now comes in contact with the paper surface all those ingredients start to interact - each one by itself and all of them in combination. It is very hard to predict, what will happen. Usually, a new recipe is tested empirically (trial and error).

A low pH-value can exchange anions (negatively charged) from a lime particle, making its surface more polar and a polar dye will adhere, while a non-polar dye will be pushed away and attaches to something else (maybe to a lignin residue in between cellulose fibres). Surfactants and lubricants can support or suppress such interactions and hydration (building a monomolecular water film around the cellulose fibre) can totally inhibit access of a non-polar dye to the fibre.

Multiple ingredients interact in so many different ways ... at some point it is better to simply follow the trial and error attempt.

 

What has turned out from the test series so far is an influence of either high or very low pH-value of inks with low surface tension on the line width and on the ink amount a nib laid down to the paper.

Most other effects can be explained by surface tension alone - but, some brand new measurement data are pointing towards a behaviour control by adding salt to an otherwise uncontrollable ink....