Experiments With Flex

[duckbillclinton]

  On 7/19/2021 at 10:09 AM, txomsy said:

I think the equations are likely a bit more complex. One needs to consider not only the flexibility gained, or the ink flow characteristics, but also the durability of the solution: if flexing a modified nib may result in undue stress, the metal may suffer fatigue and sooner or later break or suffer plastic distortion.

 

For that one also needs to consider the temper of the metal and the distribution of stress lines through the nib. Amadeus' blog has many interesting tips.

 

From the little I know about simulated annealing, steel can be tempered to be fragile yet strong or flexible but deformable, with a large range of variations, and a good nib probably needs to hit the sweet spot in the line for optimal performance. The further one departs from it, the easier it will be that the nib will break or deform, maybe at the first use or maybe after some time or only after some abuse, but that needs to be considered too. It might be that not any steel nib is susceptible for flex modification.

 

It will also depend likely on the thickness of the steel sheet. A thinner one will be more flexible but also likely less resilient. A thicker one will require more pressure and possible be more resistant. It is important not to forget that today's nibs were selected to be strong and most resistant to deformation in order to compete with ballpoint pens.

 

Stress lines will depend on nib shape. This may have little impact at the beginning, when the metal is still strong, but if the cuts are too deep or located in the wrong place, stress will be redirected and concentrate on possibly suboptimal points, leading to increased metal fatigue and, after some time, damage.

 

If I were to approach it -and had the time, which I don't- I would start thinking of alternative designs, testing them in practice and when one seemed to work, I'd be modeling it in the computer to see the distribution of stress lines in an attempt to predict its resilience. Then, I'd have to use (close to abuse threshold) every day to confirm if it can stand use and how long. Probably what nib-makers of old did, in a time when pens were used 10-12 hours a day 6 days a week by all users that would result in prompt feedback. Now it would take one of us a lot longer.

 

The reason for starting with design is that the info is readily available, one needs only look at flex dip nibs to find out suggestions for designs, whereas testing different alloys might have been an option for nib-makers of old (who could just order a sample sheet of metal and use it in their own manual nib-making presses to get test nibs, but is mostly limited to available nibs today. Plus, in the old times, it would be easier in that one would have the tactile experience to know how a good nib should "feel" in the hand as opposed to suboptimal materials and nowadays this experience is rare.

 

In hindsight, I think that the current status was driven by stock market forces: in order to compete with BPs, the best approach for FPs would have be to lower costs as well, so that schools would continue favoring them. At the time most probably thought it would undercut profit margins and lead to company decapitalization by investors, leading them to increase margins to remain attractive and instead then forced them to adagpt to new users grown with BPs by strengthening the nibs. Which is what we have now. Nails.

 

One may wonder if a cheap FP would have allowed them enough added sales to be justifiable, possibly aided by strong marketing campaigns touting the beauty and elegance of FP line-width-variating scripts over the dullness of BPs as a distinction trait; but since the market was already saturated with FPs before the advent of BPs (because there was no other sensible option), it is doubtful they could have increased sales by reducing prices.

 

One can also wonder why did makers not keep a line of flex pens for the knowledgeable, but I suppose they did until most users were so used to BPs that demand for flexibility was negligible or could not justify keeping the lines.

 

This leaves us with modern nibs engineered to be hard, strong and rigid.

 

There have been suggestions of reducing modern steel nib thickness to increase flexibility. This might be an option, but it is too difficult to master and do accurately from an amateur point of view. Which leaves us, again with modifying the overall shape in a way that increases flexibility but maintains bouncyness and springyness long enough to be practical.

 

The problem with ink flow may be dependent on the nib metal alloy and feed material (and surface tension) used, or may be attacked by modifying the ink. Ideally one would prefer a solution that requires no ink modification. And possibly that can adapt to most inks. I'm thinking of the Eversharp manifold/regulator nibs as a possible solution, but that is even more difficult to achieve for an amateur.

 

Booofff... too long a post already. Who said s/he wanted discussion?

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I am speechless again.

[txomsy]

No reason to. This has long been discussed many times here in FPN and extensively researched in the mentioned blog of Amadeus. I am just parroting those old messages.

[duckbillclinton]

Calliarts ego 3 pen, flex modded Jinhao #6 nib, heavily modded feed.

 

The experiment of such nib design verifies,

 

1. If breath hole sizing affects ink film stability -- It does! Smaller breath hole or no hole at all is highly recommended!

2. If long cut slit is needed for wide strokes -- it helps a LOT, but for less aggressive wide strokes, it is not a must.

3. If modded feed surface can help to maintain ink film (bubble) at the breath hole -- it certainly helps.

 

All my theories turned out to be correct.  It writes wonderfully, except the tip needs lots grinding and smoothing.  Also I grinded down the sides too much near the breath hole, the nib is way too soft.  For daily use, I have to add an overfeed to make it stiffer.

 

Edited July 21, 2021 by duckbillclinton

[duckbillclinton]

Another design for experiment verification, Narwhal pen, flex modded Jinhao #6 nib, heavily modded feed.  It validates,

 

- If crossflex design is required for reaching 4mm+ wide stroke

 

The results are amazing and speak for itself, ultra flex nib design don't need crossflex, just a simple design with a long slit cut and some grinding on the two sides will get you there.

 

 

[duckbillclinton]

#5 Jinhao good old 601.  Flex mod can be done on smaller nibs too, the line width reached 3mm.

 

 

[Detman101]

Amazing work!

[duckbillclinton]

  On 7/19/2021 at 1:31 PM, AAAndrew said:

As for problems with the ink film reaching the paper, I cannot speak to the science of the ink, but I can speak from a lot of experience with dip pens having trouble with ink that won't reach the paper. What I've found is that the vast majority of the time, the issue is the surface of the underside of the nib has some kind of interfering coating, usually oil, that prevents full flow of the ink. This usually happens when the underside is touched by a person, and their skin oils on the nib will prevent the ink from flowing well down the slit. Even though a fountain pen is not reliant on the hydrogen bonding in the ink to keep the surface tension as it gathers on the back of the nib, like a dip pen, instead the feed literally feeds the ink to the back of the nib, down the slit and to the paper. If the back of the nib has a hydrophobic coating (like skin oils) on it, even in a fountain pen, this will prevent the ink from flowing down the slit all the way to the point like it should. The way to solve this problem is, obviously, to remove the oil and not touch it with bare skin while working on it. 

 

Just my 2-cents from lots of experience with highly flexible dip pens and ink flow problems. 

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Excellent observation!  Indeed, all my flex mod have nibs thinned down by grinding using a dremel, and they are all done from the UNDERSIDE.  Yes, a technique commonly used by nibmeisters from the old ages.  After thinning done, I dip the nip into a bottle of ink, take it out, and carefully observe how ink is hanging (hydrophilic) or dripping (hydrophobic) from the underside.  For the most important part, I will observe if a very thin ink film/ bubble can be formed inside the breath hole.  If so, nib thinning is done with success, and the nib will be able to flex and write wide strokes.

Edited July 22, 2021 by duckbillclinton

[duckbillclinton]

This is how I cut the long slit on nib.  Very primitive, works only OK.  The cutting disk is 0.15mm in thickness.

 

Edited July 23, 2021 by duckbillclinton

[InesF]

  On 7/18/2021 at 1:23 PM, duckbillclinton said:

Just imagine we have a small strip of flat paper card, let's cut a slit in the middle (similar to a pen nib), then we press it down to a hard, flat, and smooth surface, the slit is not going to open much. 

 

As contrary, a real life example, I have 2 #6 Bock titanium nibs, very disappointing experience (comparing with the good old almighty OMAS Titanium nibs), they flex very little and too easy to spring, so I took the nib out, carefully using hand tools to increase the curvature, the results are quite good, the tines open with wider angle (wider width also), feels stiffer and no longer spring even I press down hard (but not too hard, obviously). 

 

Greater curvature will increase the tine opening angle, and also increase the resistance for bending, so the nib will become stiffer.  This also means opening up the tines required more strength, so I use hand tool again, to make the tip tilt up a bit (similar to the classic and most-pleasant-to-write Sheaffer integrated nib), that solved all the problems. 

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Hi @duckbillclinton.

Thank you, yes you got my question right!

 

It was also my consideration about geometry of curved (the cylindrical shape of a nib) tines and placement of cuttings close to the tines. You need to be careful to not remove the bending angel which is responsible for spreading the tines when you press down the nib.

 

Bending the tines of a cylindrically bent nib does not only spread the tines, it will also rotate them. I was always wondering if this rotation is important, or not.

It may influence how the ink film is pulled towards the paper (or not). I think, this is the smaller effect.

The rotation may change the form of the (opening) gap between nib and feed. And there it starts to become complicated for me - the gap will not be like a parallel (or rectangular) slit, it may be triangular because of rotating tines. A wider gap will result in lower capillary force and in increased ink flow but has the potential to cut the ink film and stop ink delivery at all (-> railroading).

 

However, as @txomsy mentioned earlier, you may calculate a lot, but final evidence comes from the experiment ...

 

... and by inhomogeneous annealing or hardening of the metal you may achieve tine bending curvatures that are not predictable from the overall nib geometry.

 

I think, constructing a fountain pen has similarities with driving a bicycle: you can do it intuitively (empirically) and chances are, you will never know why it works the way it works.

[duckbillclinton]

Whenever you mess up a flex nib mod, you can ALMOST always save it by adding an overfeed to guarantee ink film's stability.  That's why I play with different metal foils (thin plates) to make "luxury" overfeed for my flex writers.

 

I use 316L stainless steel foil a lot (0.1mm thickness), but here are some very precious metal foils I obtained recently, they are all metals from the element table with good corrosion resistance.

 

I just couldn't believe how awesome cold rolled Molybdenum, Niobium, and Tantalum turn out to be (all the same 0.1mm thickness).  These 3 metal in pure form, after cold work, have a small amount of flexibility.  Each metal has its own unique silverish color.  It's super NICE!

 

Titanium foil in pure form has beautiful color, but even cold roll and further hand tool cold work couldn't save it.  It's too soft, not enough flexibility to be any use of an overfeed.  Same applies to Nickel, pure Nickel foil is even softer than pure Titanium, so it's also no use.

 

Titanium alloy in 6AI-4V, however, is a beauty, the cold rolled foil of same 0.1mm thickness, plays wonder.  Wow!  It's very springy and flexy, nice.

 

(On the photo, I labelled Niobium and Tantalum with the wrong order, it should be the other way around.  Tantalum has cold silver color, a bit towards light blue grey silver.  Niobium has warm silver color, a bit towards light brown silver.)

Edited July 25, 2021 by duckbillclinton

[SoulSamurai]

I've always wondered why more pens don't use overfeeds. Will you share photos of the nibs with the overfeeds?

[sajiskumar]

  On 7/16/2021 at 5:04 AM, duckbillclinton said:

wow, i m shocked.  not much response from the community, so is it worthy to write an article on flex nib mod...

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very much interested to know more about your flex nib modifications. Thank you so much for sharing your thoughts.

[duckbillclinton]

  On 7/25/2021 at 7:18 AM, InesF said:

Hi @duckbillclinton.

Thank you, yes you got my question right!

 

It was also my consideration about geometry of curved (the cylindrical shape of a nib) tines and placement of cuttings close to the tines. You need to be careful to not remove the bending angel which is responsible for spreading the tines when you press down the nib.

 

Bending the tines of a cylindrically bent nib does not only spread the tines, it will also rotate them. I was always wondering if this rotation is important, or not.

It may influence how the ink film is pulled towards the paper (or not). I think, this is the smaller effect.

The rotation may change the form of the (opening) gap between nib and feed. And there it starts to become complicated for me - the gap will not be like a parallel (or rectangular) slit, it may be triangular because of rotating tines. A wider gap will result in lower capillary force and in increased ink flow but has the potential to cut the ink film and stop ink delivery at all (-> railroading).

 

However, as @txomsy mentioned earlier, you may calculate a lot, but final evidence comes from the experiment ...

 

... and by inhomogeneous annealing or hardening of the metal you may achieve tine bending curvatures that are not predictable from the overall nib geometry.

 

I think, constructing a fountain pen has similarities with driving a bicycle: you can do it intuitively (empirically) and chances are, you will never know why it works the way it works.

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Hi Ines,

 

Turning/ rorating (from nib design characteristics) and tiny bit of twisting (writing habit) of the tines will not affect much to the ink film stability.  It's a minimal surface, like soap films and soap bubbles we played with when we were little kids, with the right conditions, meaning, with proper surface tension (from the ink), closed edge or edges form by paper, the 2 tines, and the feed, proper surface geometry (hydrophilic), then ink film will always form.  Breath hole will be part of a factor affecting ink film stability, same as cross cuts on the center slit (crossflex mod), same as burs left from nib grinding/ cutting. Gravity, ink flux, ink viscosity may play a crucial part too.  However, all of such are open to discuss.

 

During the making of all my flex nibs, I have never solved or calculated one equation or formula.  There's no such need, but knowing the science behind it, is important.  Amadeus W's fountain pen design website was the one I read and reference to extensively when I first started my flex nib mod.  I made about 10 different designs, all of them flex very well, so I thought my designs were proper, that's not until reality strikes.  It turned out only 2 out of 10 nibs can perform flex writing properly and continuously like a fountain pen, the other 8 nibs became flexible dip nibs.  Even with proper pen feed modification, meaning sufficient ink supply, these 8 nibs can flex and write a few strokes if they were constantly getting dipped into an ink bottle or I keep turning the ink piston, then afterwards, it would be just unending railroading.  In fact, this is the main reason why so many of us first got interested into flex nib modding, but later on give up. 

 

So, I thought I missed something from Amadeus' website, I started reading his site and other sites/ forums again and again, only to find there wasn't anything I did wrong or missed based on these readings.  At the same time, I started lots trials and errors, and only to find that if I 100% copied the 2 successful nibs, the newly made ones would work, but if I made any slight changes, they would fail.  This is not science.  Indeed, my trials and errors did reward me with 2 working designs, so, shall I passed them to our younger generation of fountain pen fans as some precious artifacts?  No, that's just ridiculous.  I have always been taught to think scientifically since I was a little kid, and I will not accept such an outcome especially when we are already into the 21st century.  I quickly realized the failure I experienced might be something that was never widely acknowledged or discussed.  And then, here we go, ink film, minimal surface problem, film rupture velocity, film thickness due to ink flux, ink disjoining pressure, surface geometry versus hydrophilic/ hydrophobic, and etc.  I did a lot of readings on these, especially anything related to math, like certain functions and differential equations.  I did NOT need to understand or calculate any of them, all I need, is just knowing what are the variables being plugged into these functions and equations.  They will be the contributing factors (both succeeding and failing factors) for a proper flex nib design.  Till this point, I believe my research has found a lot of them (but not all), and now, my trials and errors on testing various new designs always come up with success just after some tuning or tweaking.  Like one of my early replies to others, based on statistics, if there are a large number of unknown failing factors, random distribution dictates, there will be a good chance one will never be able to find the right solution by trials and errors.

 

When I was still in college doing my math degree, the almighty professor Andrew Wiles came to my school to share his proof of Fermat's last theorem to our department, that was one of the greatest wonder done in math history.  I recognized every math symbol professor Wiles projected on the screen, but could NOT understand a damn thing.  But does it matter?  No, not at all, only thing we need to know, is that Fermat's last theorem is now proved to be true, so if ever, anyone need to prove a problem related to this theorem, it can be used as a tool.  Not to mention, for me, being a no namer student, I got my one of a life time opportunity to meet one of the greatest math geniuses, and also got a chance to shake his hands, it was just mind blowing. 

For forum posters that don't add any values to the discussion or keep spreading BS, I always go speechless/ mute with a smile.  The more they write, the more you will see their words don't make any science sense or they are against the common behavior of the science community. 

 

Now, just some metallurgy and material science 101...  Steels being used by pen nib making, especially fountain pens, are usually stainless steel.  Dip nibs use medium or high carbon steels (usually called carbon spring steel), they are prone to severe corrosion, so they must be made very cheap (Only cold working, No heat treatment to reduce cost and production complexity), and cheap in material cost, hence they can be easily swapped out and replaced.  On the other hand, fountain pen nib required longevity, and must use stainless steel for corrosion resistance.  So if we look at the history of stainless steel development and its use in fountain pen nibs, the earliest stainless steel invention was austenite based stainless steel, naturally, it was adopted for fountain pen nib making.  The beauty about austenite SS is that they are very low in carbon content, always in austenite state, and hence has good corrosion resistance and it is non magnetic.  The later development of 316 austenitic steel with the addition of molybdenum further strengthen resistance on corrosion.  316L steel, with improved steel production technology, further lowered carbon content, made corrosion resistance raise to another level.  Martensite SS was developed years after austenite SS, and it was originally invented for surgical tool use and was quickly adopted for cuttery use.  Due to the higher carbon content, martensite SS are far less corrosion resistant (with a very non scientific way of explanation, you can consider these carbon contents, on a micro/ nano level, created "battery effect", and hence the corrosion), and that's why cheap household tools with cheap grade SS, like scissors and kitchen knives, can still develop rust spots.  Not to mention martensite SS are hard to cold work, required heat treatment to max it's capabilities and to relief stress from cold work (note, heat treatment can potentially cause deformation on the subject), so Martenistic Stainless Steels are never used in fountain pen nib making.  In fact, the majority of steel fountain pen nibs use Austenitic Stainless Steel (medium price nib uses 316, high price nib uses 316L).  Due to austenite nature of the steel, heat treatment for hardening is NOT possible, and hence heat treatment NEVER has Tempering as an option.  In fact, cold worked austenitic SS will have its toughness and hardness improved, and hence comes with flexibility, heat treatment of annealing will only remove this improvement.  Austenitic SS used in fountain pen nib production usually comes in as pre-annealed ribbon rolls, and cold worked all the way to the end without any heat treatment.  You can check out Lamy's production videos (and various other brands) on YouTube as a reference.  Let me reiterate, for heat treatment, Tempering is NEVER an option for Austenitic Stainless Steel, because it's against the basic rules of metallurgy and material science.  On the other hand, martensite SS can be annealed, quenched, and tempered, but like I explained, it's never used in nib making. 

 

In general industry practice, heat treatment is not used in nib production.  So if anyone keeps talking about some magical steel and tempering for fountain pen nib making/ modding, he's nothing but full of BS.  Gold nibs, palladium nibs, platinum nibs also depend on cold work to increase their toughness and hardness, and they are also never heat treated during nib making. 

 

In addition, due to the improvement of steel production technology, the development of Ferritic Stainless Steel had became possible (keeping carbon content to extreme low level), it's super cheap, with good corrosion resistance (as good as Aus-SS), it can only be cold worked to slightly improve its toughness or hardness, it also can NOT be hardened by heat treatment, and hence again, NO tempering option in heat treatment.  Many cheap steel nibs use this type of steels, a good example would be the cheap Jinhao nibs (all.of them).  How to spot a Ferritic SS nib? Easy, just use a magnet, Ferrific SS are ferromagnetic. 

 

So that's it, all about fountain pen steel nib materials. 

 

 

Edited July 26, 2021 by duckbillclinton

[duckbillclinton]

  On 7/25/2021 at 3:26 PM, SoulSamurai said:

I've always wondered why more pens don't use overfeeds. Will you share photos of the nibs with the overfeeds?

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I already did, just pay more attention to the photos I posted. 

[SoulSamurai]

  On 7/25/2021 at 7:39 PM, duckbillclinton said:

I already did, just pay more attention to the photos I posted. 

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Sorry, some photos weren't loading for me before, but for some reason I see them now (could be because I'm on a different device right now). Thanks.

[txomsy]

  On 7/25/2021 at 7:32 PM, duckbillclinton said:

did wrong or missed based on these readings.  At the same time, I started lots trials and errors, and only to find that if I 100% copied the 2 successful nibs, the newly made ones would work, but if I made any slight changes, they would fail.  This is not science.  Indeed, my trials and errors did reward me with 2 working

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First, I found your post most interesting.

 

However, I have to chime in on this.

 

What you are describing there is actually Science and how science works. I think that you wanted to imply that it lacks a theoretical understanding, but science works actually by observing Nature, producing a hypothesis, doing experiments to test it, observing the outcome and then trying to either a ) produce a theoretical explanation which, most likely, will never be totally right but hopefully will hold for enough time to obtain new, useful predictions to produce new hypotheses, etc.. or b ) produce more experiments until you can get to a theoretical explanation, etc...

 

So, what any amateur modifying nibs and testing if that works are doing is science. It would not be if they just claimed something must work without testing and without any verified theoretical prior basis. Kinda if I said that bending upwards the tips of the tines of a nib must somehow magically produce flex. To the unknowing, such a fude design may look like flex and fool them (and maybe even me myself and that's why I'd say it), but to a trained eye it would pass as what it is, BS.

 

Some times it is easy to produce a theorem and some times it demands more experiments until one can come up with a proper explanation. It is improper explanations that lead to pseudoscience (and "magic", but note that a real magician should know the real science too --only they do hide it and give the bad science to willing spectators).

[txomsy]

Now, regarding steels.

 

I've witnessed a huge depletion of experts in Quantum Mechanics in Biology for the last 20 years as every expert diverted to Materials Science. I confess I haven't followed their developments in detail (my interest is Biology/Health), but I would expect that the accrued knowledge should be large by now.

 

I think that most likely there must be already materials (or the knowledge needed to make the materials) suitable for flex nib design, maybe even not necessarily metallic. Which leads to an economic interest POV. What I do not see is how can someone justify investing in using (or finding) them given the current demand. A surge in the interest for calligraphy might help. Or it might be that stub/italic nibs are naturally selected as they require less production work and learning to use.

 

But what I hope is that sooner or later, the interest will rise, and if not, someone with good Material Science knowledge will come up with a proposal. But then, longevity will also be an issue.

 

Shortly, I doubt that makers will have an interest in anything that is not a disposable solution for flex nibs. So I see two ways out, either get more FPs that can take disposable nibs (justifiable by the interest in Frankenpens) or amateurs continue hunting for the holy grail of a self-made, easy to make, advanced flex nib.

 

So, does anyone know of any experts on Material Science? Is really steel the best choice? Or are we unduly constraining ourselves by only considering it?

 

I'm thinking of the microcomputer revolution: in the late 70's, early 80's many amateurs built their own microcomputers using a mix-and-match of pieces (that's how I learned). Which comes to show amateurs and "hi-tech" soultions should not be despised.

 

[Pen Engineer]

i think that most likely there must be already materials (or the knowledge needed to make the materials) suitable for flex nib design, maybe even not necessarily metallic. ... txomsy said this!

 

for shua, early nibs were made of feathers and glass, and wood and bristles... is one allowed to call these items "nibs"?  They write, bring ink to paper (or sort of something).  There are good plastics around and adding a few strands of fibres along the length of the tines.

 

One thing about flex, writing in a calligraphic style, there is the human factor, the skill required and the habits we develop.  Writing and nib shaping was what the old fellows did (including myself, (old fellow)), because every hand is different.  Observing, trying out and finding out what works is what makes the skilled writer.

 

I guess, I am rattling on, in brief: good topic and I will keep on visiting

[duckbillclinton]

  On 7/26/2021 at 8:42 AM, Pen Engineer said:

i think that most likely there must be already materials (or the knowledge needed to make the materials) suitable for flex nib design, maybe even not necessarily metallic. ... txomsy said this!

 

for shua, early nibs were made of feathers and glass, and wood and bristles... is one allowed to call these items "nibs"?  They write, bring ink to paper (or sort of something).  There are good plastics around and adding a few strands of fibres along the length of the tines.

 

One thing about flex, writing in a calligraphic style, there is the human factor, the skill required and the habits we develop.  Writing and nib shaping was what the old fellows did (including myself, (old fellow)), because every hand is different.  Observing, trying out and finding out what works is what makes the skilled writer.

 

I guess, I am rattling on, in brief: good topic and I will keep on visiting

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Here comes the man. :).  Hello, Amadeus.  Thank you for your great works on the fountain pen design website.  It's very inspiring.  Cheers.

[InesF]

  On 7/25/2021 at 7:32 PM, duckbillclinton said:

During the making of all my flex nibs, I have never solved or calculated one equation or formula.  There's no such need, but knowing the science behind it, is important.  Amadeus W's fountain pen design website was the one I read and reference to extensively when I first started my flex nib mod.  I made about 10 different designs, all of them flex very well, so I thought my designs were proper, that's not until reality strikes.  It turned out only 2 out of 10 nibs can perform flex writing properly and continuously like a fountain pen, the other 8 nibs became flexible dip nibs.  Even with proper pen feed modification, meaning sufficient ink supply, these 8 nibs can flex and write a few strokes if they were constantly getting dipped into an ink bottle or I keep turning the ink piston, then afterwards, it would be just unending railroading.  In fact, this is the main reason why so many of us first got interested into flex nib modding, but later on give up. 

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Hi @duckbillclinton

What a long and comprehensive reply - thank you!

Besides your highly interesting insights in metallurgy, the paragraph I quoted contains the essence of nib design: it always was and it still is somehow empiric approximation. And we all experience that a successful design is copied by many others with only marginal changes that do not matter for the properties.

 

What I meant with irregular annealing was the heat treatment coming with tipping. You know better than me, that iron becomes harder and stiffer when heated and cooled rapidly while the opposite is for gold and many other precious metals. After pressing, cutting, shaping etc. a gold nib has, most likely, the hardest and stiffest status reached. When customizing a nib, I'm always afraid of heating and softening it partly due to the grinding. So I always work with water cooling. However, I can imagine that any (unintentional?) heating may change the flex behavior of a gold nib - the final status is maybe not only caused by the new shape after grinding or cutting side slits, but also from partly softening the material.

Sure, this is different for steel nibs.

 

Same to me, a pleasure to have Amadeus W. (@Pen Engineer) here! Indeed, I studied your information several times. And by asking myself about what makes an ink wet, my measurements do point towards a hypothesis about what makes a fountain pen nib writing wet and another one writing dry. I'm looking forward to discuss this in autumn.

 

... and now I will continue to enjoy the last days of my summer vacation. See you at the pool!  😃