Inky Terminology

[LizEF]

In a recent thread inquiring about a wet ink, the discussion turned to how terms like "wet", "lubrication", and "saturation" are used when inks are discussed or reviewed.  Another term came up: "viscosity".  I suspect understanding of these terms is either inconsistent or non-existent in many of us - and I count my former self in that group (though I still don't feel like I have as good a grasp on "viscosity" as I would like).  "Surfactant" is another term we might want to define, to aid understanding overall.  (I'm open to more being added, as needed.)

 

In this thread, I'd like us to discuss and attempt to define these terms in a way that nearly anyone can understand without having to go take chemistry and physics classes.  We should feel free to get as scientific as we wish, but the end goal should be a short explanation of each term, in hopes that an inky moderator will then "sticky" those definitions in or around the ink review forms which ask the reviewer to rate or evaluate these attributes of the ink.  We may also wish to discuss how these attributes impact other things, like dry time, shading, and sheen.  In essence, we will be creating a glossary that includes not only definitions, but examples, cross-references, and perhaps even instruction on how to gauge these attributes for oneself.

 

As a reference, I'll add a link to "How I Test Ink Viscosity" by An Ink Guy on YouTube.

 

Finally, I'll give examples of things that I'm sure fit our discussion, but which don't help with understanding.  The following is Monteverde's description (from this page) of their "ITF technology" (bolding is mine):

Quote

Each ink is carefully crafted for use in your favorite fountain pens using ITF™ technology; aiding in maintenance by improving ink flow and extending cap-off time, all the while lubricating your fountain pen feeding system.

 

I'm with them right up until the bolded sentence.  What does that mean?  Does that mean it lubricates the piston in my piston fillers / converter / vacuum fillers, etc.?  Does it mean that it somehow lubricates the feed (and nib slit)?  Both?

 

Related is the fact that Noodler's "Eel" line of inks are often described as "lubricating" (that's even the menu item where you'll find them on Noodler's website), which has confused many a user.  From some Goulet video (sorry, not gonna go try to find it), I learned that the intent was for the ink to lubricate the piston in piston fillers.  But I have read users' assumptions that it means lubricating the nib on paper, and unless you happen to see something that tells you otherwise, it's hard to blame anyone for that assumption.

 

Please share your thoughts or feel free to kick off introductory definitions of (one or more) these terms.  If no one beats me to it, I'll return in a hour or two to take a stab.

 

[yazeh]

Nice one Liz.

Inks can be wet without being lubricated. 

Lubrication gives a cushiony feel to the nib IMHO. But to me it's a tactile and thus subjective.

Viscosity: I have noticed General of the Armies is particularly viscous. It's not as watery as Caran d'Ache inks. However, it's a wet ink

 

[bunnspecial]

I'll take a stab at one-

 

"Viscosity" is just referring to how well a solution flows. As extreme examples, think of pouring water out of a bottle vs. pouring maple syrup or molasses. The former will flow out easily, while the latter will pour slowly.

 

Of course in inks the differences are a lot more subtle, but essentially a less viscous ink will "flow" out of the pen easier than a more viscous one, all else being equal.

[LizEF]

Flow (wetness): This refers to the rate, or speed, at which an ink will flow out of a pen.  (This appears to be equivalent to viscosity - that is, an ink's viscosity dictates the rate at which it flows.  It also appears to either be or relate directly to surface tension.  It appears to be related to the presence of surfactants in the ink.)

 

A wet ink, or ink with "wet flow", will flow more quickly from the nib, putting more ink on the page, sometimes enough that you can actually see a three dimensional bead of ink.  A dry ink flows slowly from the nib, you're less likely to get that bead of ink or even the impression of wetness on the page.  (But see comments on "dry time", which I'll make in a later post.)

 

Flow or wetness (aka viscosity) may impact dry time and lubrication, but is not the same.  Please see the definitions for those terms.

 

Dictionary definition of viscous: "having a thick, sticky consistency between solid and liquid; having a high viscosity."

 

Dictionary definitions of viscosity: "the state of being thick, sticky, and semifluid in consistency, due to internal friction." and "a quantity expressing the magnitude of internal friction, as measured by the force per unit area resisting a flow in which parallel layers unit distance apart have unit speed relative to one another."

 

This suggests to me that, for FP ink purposes, a "high viscosity" is dry and "low viscosity" is wet.  This is consistent with "An Ink Guy" rates inks, with higher numbers for drier inks, lower numbers for wetter inks.

 

For anyone with too much time on their hands, it seems like reading up on Viscosity, Surface Tension, and Capillary Action would make a good personal physics class.  Wikipedia's animation for viscosity makes things very clear, for the visual learner.  (I'm not entirely certain, as I don't have too much time on my hands right now, but it appears surface tension may impact viscosity but the two aren't the same thing.)

 

Since it may be simpler to discuss each term separately, I'll post them separately and you can reply to each separately.  (We may abandon this "naturally" since these things relate to each other, but it's a starting point.)

[LizEF]

27 minutes ago, bunnspecial said:

I'll take a stab at one-

 

"Viscosity" is just referring to how well a solution flows. As extreme examples, think of pouring water out of a bottle vs. pouring maple syrup or molasses. The former will flow out easily, while the latter will pour slowly.

 

Of course in inks the differences are a lot more subtle, but essentially a less viscous ink will "flow" out of the pen easier than a more viscous one, all else being equal.

  I decided to expand a reply into more detail so we can explore in more detail before narrowing it down - and perhaps even decide not to narrow it down.  Perhaps potential reviewers who get spooked by the idea of rating an ink's rate of flow or degree of lubrication need more detail rather than less.  And, since everyone learns differently, perhaps we need multiple ways of explaining the same thing.  (Just thinking out loud here.)

[A Smug Dill]

19 hours ago, LizEF said:

What does that mean?  Does that mean it lubricates the piston in my piston fillers / converter / vacuum fillers, etc.?  Does it mean that it somehow lubricates the feed (and nib slit)?  Both?

 

As far as my understanding goes, a lubricant (i.e. lubricating substance) essentially reduces friction between two touching physical surfaces that are moving against each other. The viscosity, fluidity and/or flow characteristics of the substance itself, and how strongly or weakly it would adhere to the physical surfaces in contact with it — whether they are an ink reservoir's inner walls, the rim of a piston plug, ink channel on a feed, the underside of a nib, or opposite inner surfaces on its tines — are logically separate from what defines it as a lubricant.

 

There isn't anything in a Pilot fountain pen's feeding system to lubricate if you're using a CON-B or CON-20 converter as the ink reservoir, when the pressure bar with which to squeeze the sac is outside and does not come into contact with the ink. If you're using a CON-40 converter to fill and feed the pen, drawing ink up (from a bottle, vial or inkwell) through the nib and feed into the reservoir is unlikely to cause the ink to get so far up the converter's tube to reach the rim of the rotary-driven piston plug; in which case, “all the while lubricating your fountain pen feeding system” is pretty meaningless. Come to think of it, that is the case with piston-filled pens such as the Pelikan Souverän models as well. The feeding system that keeps the ink flowing and the pen writing has no moving parts in its normal operation; but it is the filling system that has moving parts where friction is a consideration.

 

Then, taking this now in a different direction, some facet(s) of the tip of a pen's nib will come into contact when writing (or drawing) with it on paper. Does a lubricating ink — for as long as it remains strictly between the metal and the page surface, as opposed to having been absorbed into the paper's fibres and/or combined with its coating (or sizing) — reduce friction in pen strokes more than not overtly lubricating inks do? Does some component of the lubricating ink bind with the paper's surface and effectively glazes it to lower the friction coefficient (where there are ink marks) persistently? Or is there only a split-second, just before the ink is fully absorbed into the paper's substrate, when coefficient friction between the nib tipping (that just delivered the ink onto the page surface) and paper is lowered, in a way or to an extent that a not overtly lubricating ink would not?

 

In any case, a good lubricant does not have to be present in abundance or to the point of excess, in order to do its job of reducing friction; so an ink formulated especially to act as an effective lubricant between nib and paper with each pen stroke need not be a ‘wet’ or readily flowing ink.

[LizEF]

6 hours ago, A Smug Dill said:

...

In any case, a good lubricant does not have to be present in abundance or to the point of excess, in order to do its job of reducing friction; so an ink formulated especially to act as an effective lubricant between nib and paper with each pen stroke need not be a ‘wet’ or readily flowing ink.

Agreed!  And your post is a great exploration of what exactly lubrication means.  Thank you!

 

FYI, my main point was that Monteverde's phrase could only serve to confuse the discussion, not help it.   I suppose if they intend this ink to help with piston operation (as is the claim (by one, at least) with Noodler's Eel ink), then one would have to assume it's designed to work its way between piston and wall.  But then it sure seems probable it would bring dye with it, and who wants that?  Anywho, not our main point.

 

I'm in the midst of updating my reviews with scans (of questionable worth, but sometimes I get a little OCD) and USB microscope pictures of writing on "absorbent paper".  Once that's done, I'll come back here to take a stab at more definitions, explanations, and/or instructions.

[A Smug Dill]

19 minutes ago, LizEF said:

… one would have to assume it's designed to work its way between piston and wall.  But then it sure seems probable it would bring dye with it, and who wants that?  Anywho, not our main point.

 

Indeed, I'm sure most — if not all — of us have seen some tiny amount of ink somehow working its way over to the ‘wrong’ side of a piston plug. An ink-repelling lubricant applied to the rim or sides of a piston plug would improve the seal of an imperfect fit between the plug and the walls of the reservoir, whereas if the (lubricating) ink itself acts as the lubricant, then surely it just makes the seal even less perfect, since the substance filling the microscopic gap(s) cannot then repel the ink that is in the reservoir with which it is homogenous! I'd be greatly concerned about that.

 

I'm not sure whether it would have an impact on the ink flow rate (i.e. its ‘wetness’) down through the feed and nib onto the page surface, though.

[LizEF]

OK, I went and looked at the ink review forms and suggestions for what to include in an ink review, and the only three terms that seemed like they might be difficult for a new reviewer are:

• Flow (which we've started)
• Lubrication (which we've started)
• Saturation

I think I'll start saturation next because I think it can have at least an indirect impact on flow and lubrication, even if most of us don't have the ability to measure the relationship, we should be aware of it.

[A Smug Dill]

11 minutes ago, LizEF said:

I think I'll start saturation next

https://www.fountainpennetwork.com/forum/topic/349279-ink-report-sheets/?do=findComment&comment=4248734

 

[LizEF]

20 minutes ago, A Smug Dill said:

https://www.fountainpennetwork.com/forum/topic/349279-ink-report-sheets/?do=findComment&comment=4248734

 

Thank you.  I'll go read that before finishing my next post (which is barely started anyway - today seems to be the day of distractions).

[OutlawJosey]

Nothing of substance to contribute here, but thank you for this thread!! This is awesome.

[LizEF]

1 hour ago, OutlawJosey said:

Nothing of substance to contribute here, but thank you for this thread!! This is awesome.

Thank you for saying so - it helps a bit (for me, at least) to know that there is interest and potential for folks to make use of our results.

 

PS: I'm now way behind as my brother called and after discussing his interests in Porsches, we discussed my uneven lighting and how to fix it.  My conclusion is that I'm going to need two more of the lights I already have.  Hopefully that will provide even coverage.  Sigh.

[LizEF]

4 hours ago, LizEF said:

OK, I went and looked at the ink review forms and suggestions for what to include in an ink review, and the only three terms that seemed like they might be difficult for a new reviewer are:

• Flow (which we've started)
• Lubrication (which we've started)
• Saturation

I think I'll start saturation next because I think it can have at least an indirect impact on flow and lubrication, even if most of us don't have the ability to measure the relationship, we should be aware of it.

Maybe we should add things like permanence, light-fastness, water-resistance - reviewers likely make their own rules as to how to rate or measure these, and if some commentary were included in our would-be glossary, it might help add a bit of consistence.  (Though to do a meaningful light-fastness test is a long-term project and doesn't likely fit most review scenarios.)

[LizEF]

Saturation

I'll start by pulling in two of the dictionary definitions:

 

Quote

the state or process that occurs when no more of something can be absorbed, combined with, or added.
 

Chemistry: the degree or extent to which something is dissolved or absorbed compared with the maximum possible, usually expressed as a percentage.

 

Thus, saturation in ink reviews describes the "dye load" or what percentage of the total possible amount of dye that could be dissolved in the ink is actually present.

 

In my experience, the easiest way to measure this is to look for shading (inks which shade are not fully saturated; fully saturated inks do not shade), or to do a multi-pass swab (or similar - e.g. with Pilot Parallels) pass, overlapping a portion of the previous swab - usually, 3 passes are done.  Here's an example from a google image search:

 

The fact that you can see different shades of lightness / darkness between 1, 2, and 3 indicates that this ink is not fully saturated.  I have seen inks where 1, 2, and 3 are indistinguishable, inks where 2 & 3 are indistinguishable, and inks like the above, where all three are different.

 

NOTE: I believe it's possible to do this wrong and get false results.  The goal is not to dump as much ink as possible in every pass.  On the contrary, each pass should lay down a thin, but solid layer of ink.  I think Pilot Parallels and similar pens / nibs are better for this than saturated cotton swabs.  (I came to this realization looking at some Goulet ink sheets where the writing showed shading, but the three passes were indistinguishable.  The only way that's possible is if the swab passes put down an excess of ink.)

 

Anyone have better ways to measure saturation / dye load?  Suggestions for defining the term or offering instruction or examples.

 

Other Comments

Over in the thread @A Smug Dill linked, there is mention of the other type of saturation, which I'll describe with another dictionary definition:

Quote

(especially in photography) the intensity of a color, expressed as the degree to which it differs from white.

 

This use is for artists who are presumably trained on the subject, and I suspect it's lost on most of us.  (A search for "color saturation chart" will reveal more than most of us want to know.)

 

IMO, this is not what most reviewers mean by saturation (they mean the former, chemistry, definition, or "dye load").  Further, I think most humans would have a much harder time accurately describing this "color saturation" than describing the "dye load".  And to top it off, I think most consumers either don't care (they just care whether they like the color) or can judge for themselves by looking at the images.  It may be valid to mention as a footnote that if the reviewer wishes to comment on "color saturation", they should label or describe it as such or in such as way as to distinguish it from "dye load".

[LizEF]

It occurs to me that images would be a good thing to include in our glossary.  And that dedicated images would be far better than some image I yanked off the internet.  To that end, when we're ready, I think I could make the needed images.

 

Saturation is one thing for which we can include images.  Water-resistance might be another.  The other terms would need audio and/or video, if anything at all could demonstrate them.  (Technically, lightfastness could use images, but I'm not really sure we should include it at all, but whether we do, making new images isn't gonna work as it would take too long.)

[LizEF]

46 minutes ago, LizEF said:

permanence

If we do cover this one, we might mention why some solvents are used beyond just water - like ammonia - for the longest time, I had no idea why VittaR on YouTube was using it.  Eventually I learned that it's an ingredient in pen flush and a really good way to remove ink from at least some things, so it makes sense if the user wants to know about resistance to removal.

 

Anybody wanna buy me a laser so I can test Noodler's Warden inks?

[A Smug Dill]

4 hours ago, LizEF said:

Maybe we should add things like permanence, light-fastness, water-resistance - reviewers likely make their own rules as to how to rate or measure these,

 

I'm increasingly inclined to conclude that ‘water-resistant’ and ‘waterproof’ simply cannot be traits of an ink as the substance under review, when the solvent in fountain pen inks is primarily water. Instead, they describe a characteristic of the marks made with the ink on a surface; and so the type of paper*, the method of application — not just that there's a difference between a cotton swab and the hard metal tip of a nib, but also how hard the nib is pressed onto the paper since it may either compromise the coating/sizing on the paper surface, or make the fibres/filler more densely packed along the ink marks, thus changing the paper's ink absorption characteristics —  and the volume of ink applied (and this is where ‘wetness’ may come into play) could affect it. Ink marks made with, say, Sailor Seiboku may be waterproof on one type of paper but not so much on another.

 

I myself have been guilty many times over of (mis)using ‘water-resistant’ and/or ‘waterproof’ to describe inks, in my ink reviews and in other discussion threads.

 

On the distinction between ‘water-resistant’ and ‘waterproof‘, I'd say that the latter means unaffected by exposure to and prolonged contact with water — no colourants in the dried ink marks get dissolved and seep off the page into the bath into which the paper is submerged, or are chemically affected to change the clarity/definition (including by induced feathering) and apparent colour of the ink marks, and so on. Whereas I think there are two different aspects to ‘water-resistant’: how well the ink marks resist being physically or chemically changed by exposure to water, and whether the information content of the ink marks remain legible/retrievable afterwards.

 

Also note that mechanical erasure may come into play, when testing for water resistance and/or waterproofness. Ink marks made by pigment inks may well be waterproof when just soaked (even for days on end), but putting them under a running tap or subjecting them to a pressurised jet of water may cause physical removal of the some of the pigment, with or without damaging the surface layer of the paper. 

 

Then there's this:

https://www.fountainpennetwork.com/forum/topic/355628-struggling-to-find-a-waterproof-black-for-watercolor-sketches/?do=findComment&comment=4357317

 

 

* There are just so many aspects to this. What is the paper made of — specific type(s) of wood pulp, cotton, or even stone? Is the finish cold-press or warm-press? Is there some sort of coating, sizing or glazing applied to the paper surface? How fine or long are the fibres, and how densely are they packed (which goes beyond measuring paper weight by gsm or g/m², when a particular 120gsm paper that is twice as thick physically as a particular 80gsm paper would be less dense than the latter)? Does the grain matter? I think we really need expert input on this, especially in how the different aspects would affect the penetration and/or absorption of the ink, and the binding of the colourants to the paper.

[TheDutchGuy]

Great topic and ditto contributions! 👋 As someone trained in science, I have a built-in appreciation for the kind of distinction made in this topic, such as the previous one by Dill about water-resistant and water-proof. On a similar note, I’ve always maintained that inks don’t shade but it’s the pen that makes an ink shade. Ink is just a fluid and shading is caused by uneven application of the ink on the page (all other factors remaining the same). The ability to sheen, on the other hand, is a property of the ink (albeit influenced by the wetness of the pen). On the other hand... if someone says ‘dude, this ink is wet!’ then I know what is meant. The realisation that it might just be the pen that is wet and not the ink, that writing pressure and choice of paper matter, all of that is instantaneously understood and need not be expressed explicitly. To put it very differently, discussing pens and inks can just be fun, without a need for strict science. Having said that, topics like these are a joy.

[A Smug Dill]

3 hours ago, LizEF said:

In my experience, the easiest way to measure this is to look for shading (inks which shade are not fully saturated; fully saturated inks do not shade),

 

I'm not sure about that. Going by that sense of the word ‘saturation’, if you added more dye to a fully saturated ink, the dye simply won't dissolve; but if the dye is of a light enough colour, then spreading a fully saturated ink (thinly) on paper would still produce shading, on account of more ink is physically deposited, or allowed to pool and then dry, on some parts of certain pen strokes and intersections of ink tracks.

 

3 hours ago, LizEF said:

IMO, this is not what most reviewers mean by saturation (they mean the former, chemistry, definition, or "dye load").  Further, I think most humans would have a much harder time accurately describing this "color saturation" than describing the "dye load".

 

I'm not sure about that either. A dull blue-grey is less saturated than a vivid light blue as far as colour goes; that's easy.

 

But the former may just have more dye per unit area covered by ink marks — which may be because the ink is highly saturated, or because the ink was applied ‘wetly’, or both — than the latter. So, when I say a particular writing fluid is an “under-saturated blue ink”, would I be talking about the colour saturation or the dye load?