Measuring Ink Viscosity

[ac12]

My search for this topic failed so here is the question.

Is there anything that can be used to measure the viscosity of different inks?

We talk about wet and dry inks, but there is no measure of how wet or how dry. And comparing inks if not in the same room done by the same person is not possible or VERY difficult.

 

In looking at different ways to measure viscosity of fluids, I found 2:

1 - time a falling object (steel ball) falling through a column of fluid,

2 - time the time it takes for X volume of fluid to pass through a restricted size hole of Y size.

 

Ink gives us a problem. You can't see through dark inks. So anything requiring us to watch a falling ball won't work on the dark inks, as you can't see the ball in the dark ink. So without electronic devices to detect and time a falling steel ball, that is out as a measuring method.

 

So we are left with measuring the time it takes X amount of fluid (ink) to flow through a hole of Y size. The problem is how to do this repeatedly? And with enough precision that one can measure the different inks. A 0.1sec difference between the wettest and dryest ink is essentially 0. The time difference is too small.

 

Any ideas from you scientists and fluids guys?

[Algester]

think the viscosity test for ketchup and adapt that to inks

[musicman123]

Well, a simple but expensive way would to be buying an electronic viscometer like one found here.

 

http://m.ebay.com/itm/like/111590343791?lpid=82&chn=ps

 

Another food for thought is that surface tension of the ink plays a big part in how wet or dry something is, but is independent of viscosity.

[kwzi]

Well, a simple but expensive way would to be buying an electronic viscometer like one found here.

 

http://m.ebay.com/itm/like/111590343791?lpid=82&chn=ps

 

Another food for thought is that surface tension of the ink plays a big part in how wet or dry something is, but is independent of viscosity.

 

Rotatory viscometers (which you show) are going to give better results with liquids that are significantly more viscous than water.

If we do not want to spent to much money on equipment measuring time of flow of large amount of ink (50-100 ml) through small hole would be enough.

[torstar]

think the viscosity test for ketchup and adapt that to inks

 

somewhere between PR Tanzanite and an unshaken bottle of Noodler's Plains of Abraham.

[pepsiplease69]

Well, a simple but expensive way would to be buying an electronic viscometer like one found here.

 

http://m.ebay.com/itm/like/111590343791?lpid=82&chn=ps

 

Another food for thought is that surface tension of the ink plays a big part in how wet or dry something is, but is independent of viscosity.

 

 

I thought the wettness of an ink had more to do with the surface tension as well.

 

Highly viscous substance would be molasses or honey. Most other solutes dissolved into water as a solvent, unless the pigments cause the solutiont to thicken, for example xanthan, will largely have the same viscosity as water.

 

Wetter inks have lower surface tension. The film that surrounds the ink is weak. So when the ink is dripped, the water drops form, but they are small.

 

As the formation of a water drop is basically a competition of the liquid's surface tension versus the weight of the liquid. Originally the surface tension causes the liquid to stay put, and the moment the weight of the liquid wins out, the water drop creates.

 

So if you take any sample ink, and try to drip it with a dropper, it will form a certain size drop. Mix some dish soap into that ink and try to see again, and you will see much smaller drops forming.

(please try with a small sample of ink, don't ruin your entire bottle of ink with this experiment)

 

Weaker surface tension is what causes the liquid to coat the surfaces it comes into contact with. Drier liquids with greater surface tension would form water dropos on the surface and wouldn't coat the surface. Of course the surface that has to be coated plays a big role in this as well.

 

Check out this awesome video of a laser etched metal surface that is deemed super water-resistant and dry.

 

Going back to your question about measuring the wettness of an ink. I found this neat little gadget called a tensiometer.

 

This will gross you out, but they need to measure the surface tension of urine to determine liver function. Bile salts tend to decrease the surface tension of Urine and can be used as an indicator.

 

It's a glass tube with a narrow channel similar to a capillary going through the middle, open at both ends. And there are markings on the tube.

 

When one end of the tube is dipped into a liquid, the surface tension causes the liquid to shoot up a bit through the bore.

 

You can measure how strong the surface tension is, by seeing how much the water shoots up. Water should have the highest surface tension, and as we switch to inks that have surfactants mixed in them, they weaken the surface tension so less of the liquid should shoot up through the bore.

 

Watch this youtube for a demonstration.

 

I contacted the guy and picked one of these up for myself, it cost $75, so not that bad. But I haven't had the courage to dip it yet in any of my inks.

[kwzi]

I do not want to discourage you but for measuring surface tension of ink with capillary is not that simple. You will need to know precise diameter of capillary, properties of liquid like: density and it contact angle. Liquid that is drawn higher in capillary is not necessarily the one with lower surface tension!

Determination density of the ink is not much of a problem, although measuring contact angle of ink is very problematic. It can be achieved by using two capillary with different diameters and a bit of math, but you have to be sure that they are made from the same type of glass. Determining contact angle is important because components of ink can significantly change contact angle of ink.

[jmccarty3]

Very interesting insights. On a related note, I managed to score what must be one of the few remaining bottles of Organic Studios Flo Plus last week. This will be interesting to try on some of my higher surface tension inks.

[ac12]

 

Very interesting insights. On a related note, I managed to score what must be one of the few remaining bottles of Organic Studios Flo Plus last week. This will be interesting to try on some of my higher surface tension inks.

 

I would be interested in going in the opposite direction, drying out some WET inks.

[pepsiplease69]

 

2 - time the time it takes for X volume of fluid to pass through a restricted size hole of Y size.

 

 

 

I just thought of another idea.. Here goes..

 

 

You fill the ink in question via a syringe into a fairly transparent/translucent cartridgethat is on the tall side. Say maybe a Lamy or Parker cartridge or standard international. Leave a tiny air bubble inside, do not fill all the way to the top. Hold the cartridge bottom-up so the bubble is sitting at the back. Then tip the cartridge to the other side, ie. make it frontside up, maybe a 45 degree angle.

 

If the ink is viscous, that bubble is going to take a certain amount of time to rise to the front side of the converter. That time can be noted.

 

If the ink is fairly thin, the bubble will come to the front fairly quickly.

 

This can be used to do a comparative study to see whether ink X is how many "seconds" more viscous than water.

 

Or ink X is this many seconds viscous versus ink Y is this many.

 

As I was playing with my lamy cartridge, this idea came to me, the bubble would travel slowly up the cartridge, and some of that was due to the ink viscosity.

 

Here are some factors to consider, and keep constant while trying to do a comparison.

 

• Temperature of the liquid
• The cartridge being used (inner surface of the cartridge has a certain smoothness or coarseness)
• Tipping angle (want to keep this constant so that the ascent of the bubble is nolonger influenced by the buoyancy and gravity force alone when going from ink to ink, but also the ink viscosity)
• Size of the bubble

 

One of the problems would be:

• If you have a fairly opaque ink that thickly coats the inner walls of the cartridge, the bubble might be hard to see.
• If you have a stubborn ink that is too "clingy" and the bubble doesn't want to budge from the bottom and stay there (due to surface tension being too high), a coarse walled cartridge, or one with channels/grooves along the walls might be good to combat this.

 

I don't know I'm just brainstorming here..

Edited March 4, 2015 by pepsiplease69

[amberleadavis]

 

somewhere between PR Tanzanite and an unshaken bottle of Noodler's Plains of Abraham.

 

That's funny.

 

OP, have you tried any of the suggestions?

[ac12]

Not yet. Unfortunately I'm not a lab type with access to glass tubes, stand, clamps, bunsen burners, etc. And I passed up the stand and clamps at a flea market years ago. So I have to figure out how to cobble something together. I'm thinking of how to implement the tiny hole method, and do it so I can collect the ink, to use, rather than have it mess up and flow all over the counter.

 

Now I am curious about how Sheaffer and PR DCSS blue compare in wetness/viscosity to Waterman and Cross/Pelikan ink.

[amberleadavis]

I look forward to seeing it too.

[Randal6393]

None of this has much to do with what most of us want to know -- How well does it write? In a particular pen?

 

Have fun, guys and girls.

[pepsiplease69]

None of this has much to do with what most of us want to know -- How well does it write? In a particular pen?

 

Have fun, guys and girls.

 

 

I guess the scientist in us wants to know what's under the hood with the ink.

 

How well it would write would be a function of various factors, primarily the ink properties, viscosity, surface tension, the quality of the paper and the shape of the nib.

 

I could, for example tinker with the ink constitution. If I don't like the way it writes, it's too dry, I could add a surfactant (dish soap) and it would flow much wetter etc.

 

Without knowing the science that goes into the process of how the pen and ink work, it would all appear to be guess work. You can test various inks with various pens and various papers and if one is a good match, then you stick with that combination, not knowing why it's a good match.

[Sandy1]

Hi,

 

To make the results relevant to end-users, one would also need to factor in the most important aspect - capillary action - which drives FPs' ability to write , and is greatly influenced by the ink+pen+paper dancing at the nib tip when ink is handed-off to the paper. (Sometimes accompanied by Ink Putti playing ancient tunes on 5-string banjos, trombones & accordions)

 

Also wettability of the material used for testing vs. FP components (nib+feed.)

 

Please note that a prior Topic Ink Rheology touched on similar avenues of investigation, but no results were forthcoming, yet may provide some insight : https://www.fountainpennetwork.com/forum/index.php/topic/265601-ink-rheology/?p=2974769

 

Bye,

S1

 

Wiki 'wettability' http://en.wiktionary.org/wiki/wettability

Wiki 'rheology' http://en.wikipedia.org/wiki/Rheology

Edited March 12, 2015 by Sandy1

[torstar]

 

That's funny.

 

OP, have you tried any of the suggestions?

 

Amberleadavis, did you ever obtain a bottle of Noodler's Plains of Abraham? I did, probably well after it's expiry date... the horror.... the horror....

 

Not even 1% mitigated by Canadian history pride...

Edited March 12, 2015 by torstar

[amberleadavis]

No, I never did try it. I'm so sorry for the disaster. I found so many of the proprietary Noodler's inks were so dry that I couldn't take it. I have a low tolerance for fussy inks - I'm addicted to wet inks and get grumpy when anything dries out too easily.