E-Juice Viscosity Test?

[Ralph T]

Has anyone thought up a way to measure viscosity of the e-juices?

It seems that the cart mods are hit and miss and I suspect that the big variable is the thickness of the juice. Mods that work well for thick juice produce a flood on the thin stuff. Mods that work for the thin stuff, run dry with the thick juice. If we had a measurement of thickness, then we could be more precise when selecting a mod that would suit the juice.

So I am trying to come up with a way to measure this. It would have to be cheap, repeatable and fairly accurate. It would also be a big bonus if it didn't waste much if any juice!

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Another Festivus Miracle

 

[Rocketman]

Ralph,
I have a method I use that does not produce a real viscosity value, just a relative value that is repeatable. I use a 10ml ink cartridge hypo with a rather LARGE blunt needle. I run VG through it and the drop time is about 12 min/ml. I have some PG that may have absorbed some atmospheric water vapor that drops at about 1.5 minutes per ml. A few different PG based Chinese Juices that also drop at about 1.5 minutes per ml.

Cutting the PG and VG with distilled water at about 10%, 25%, 50% gives an exponential curve of decreasing drop times. Pure water is about 1.5 Seconds per ml.

I vape 50/50 juice (PG/VG) and cut it with 100 proof Vodka (water and ethanol, right?) to get between 1 minute and 1.5 minutes per ml drop time. Without dilution the 50/50 (if PG Nic juice I cut with VG, and if VG Nic juice cut with PG) gives about 3 minutes per ml. Let the needle run for about 1ml then start timing. Should be laminar pipe flow by that time. Measure over a few ml and column pressure drop shouldn't matter between liquid as most are pretty close to the same density anyway. My 50/50 was too thick to wick, and my dilution wasn't repeatable. Now it is. And you drop from the syringe into a bottle so it ain't wasted.

The Rocket

 

[Ralph T]

Ralph,
I have a method I use that does not produce a real viscosity value, just a relative value that is repeatable. I use a 10ml ink cartridge hypo with a rather LARGE blunt needle. I run VG through it and the drop time is about 12 min/ml. I have some PG that may have absorbed some atmospheric water vapor that drops at about 1.5 minutes per ml. A few different PG based Chinese Juices that also drop at about 1.5 minutes per ml.

Cutting the PG and VG with distilled water at about 10%, 25%, 50% gives an exponential curve of decreasing drop times. Pure water is about 1.5 Seconds per ml.

I vape 50/50 juice (PG/VG) and cut it with 100 proof Vodka (water and ethanol, right?) to get between 1 minute and 1.5 minutes per ml drop time. Without dilution the 50/50 (if PG Nic juice I cut with VG, and if VG Nic juice cut with PG) gives about 3 minutes per ml. Let the needle run for about 1ml then start timing. Should be laminar pipe flow by that time. Measure over a few ml and column pressure drop shouldn't matter between liquid as most are pretty close to the same density anyway. My 50/50 was too thick to wick, and my dilution wasn't repeatable. Now it is. And you drop from the syringe into a bottle so it ain't wasted.

The Rocket

Dude, YOU are effing brilliant. I had suspected that someone out there had come up with a home-spun way of doing this. Doesn't need to be precise with regards to "scientifically accepted method" or a particular unit of measurement.

It would be awesome if we could figure out a way for just about anybody to test their juice and report back. That will require off the shelf equipment (think Walgreens or Walmart) and a simple method. I think you are almost there already with this. The variable here is the syringe (with or without needle). If we could nail that down to a model you can get in any Walgreens.

I am thinking that the reference standard would be water and juice viscosity would be a multiplier. So for instance if it takes 1 minute per ml to drip water, then maybe straight PG is 1.5 mpml (thru some standard equipment).

I have a B&D "oral" syringe that is 1ml, major graduations are .1 ml, minor grads .02. I am going to play with that. Also occurs to me that the juice needs to be tested at a pretty standard temp. Colder = thicker and all that. Maybe 68F?

Open to all ideas.

 

[sjohnson]

Once you have a standard juice that works for your setup, the temperature need not matter. Just time your standard juice first and use that as the target.

Time to drip a standard volume through a standard hole is all you need. You might be able to use one of the cheap medicine 5 ml plastic droppers instead of a syringe/barrel combo. Take off the pump bulb and make a stopper for the end (or use a clean finger) and time dropping X ml after a priming 1 ml drop.

 

[Marctwo]

I think for most it wouldn't matter what equipment is used. A factor of the speed of water could be used with any similar equipment to reproduce with appropriate accuracy.

 

[Ralph T]

I think for most it wouldn't matter what equipment is used. A factor of the speed of water could be used with any similar equipment to reproduce with appropriate accuracy.

I agree with you and Johnson. However, if we were to "talk juice" thickness, we would have to be on the same measuring page. Or it could be that we need to simplify the math so that everyone can establish a base level, adjust for their variables, and speak a common viscosity. Essentially guys and gals, we are talking about developing a standard by which juice viscosity is measured and discussed..... To compare vaping and "mod" effectiveness, by directly comparing a factor of our juice... in this case viscosity... with others experiences.

For instance, if you posted that "the ZFM mod worked great with a 50/50 pg/vg juice at 7.5 mdpm (perhaps ml drip per minute), but I ran the same juice dry on the blue foam. But the 2.4 mdpm 10%VG juice from juiceboys works great in the blue foam plug mod 7". Now that would mean something.

At the moment, the thickness of the juice is not really taken into consideration with the particular mod being tried/tested. So, when comparing mods we don't know our apples from our oranges.


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Sorry I slurred that out. We celebrated Festivus yesterday and my kids were kinda hard on me during the "Airing of Grievances" portion of the ceremony. So I am no stranger to "Jack" and coke tonight.

 

[Marctwo]

My point is that an absolute scale of something like ml per min would require the same equipment to replicate. You'd need the same opening, finish, edge shape, length, etc.

By using a scale relative to water you can simply calibrate any appropriate equipment by measuring water with it first.

 

[Ralph T]

My point is that an absolute scale of something like ml per min would require the same equipment to replicate. You'd need the same opening, finish, edge shape, length, etc.

By using a scale relative to water you can simply calibrate any appropriate equipment by measuring water with it first.

Point taken. I can see how this could work.

 

[Raenon]

My point is that an absolute scale of something like ml per min would require the same equipment to replicate. You'd need the same opening, finish, edge shape, length, etc.

By using a scale relative to water you can simply calibrate any appropriate equipment by measuring water with it first.

Wouldn't surface tension throw off this measurement significantly with smaller syringe/dropper widths versus larger?

 

[Marctwo]

Wouldn't surface tension throw off this measurement significantly with smaller syringe/dropper widths versus larger?

Well, that's the sort of thing that testing is for... to determine what is and isn't appropriate.

I think we can allow quite a wide tolerence with this and still be far more accurate than necessary.

I'll be doing a few tests myself to see the results from as wide a range of things I can find lying around.

 

[exogenesis]

Personally I think the massive difference between PG & glycerol
(in viscocity terms) could well cause a difference in experience
with various mixtures.

You could view PG as 'too thin & leaks from the atty somewhat',
and glycerol as too thick to flow in the atty, so I've got to add some water.

The amount of water you need to add to glycerol to make it flow like
PG is 1/6 th to 1/5th by volume (at room temp., it's temperature dependent).

Done some tests of flow-rates through an aperture,
using serological pipettes, to check they're the same.


If you're not working in absolute units, then it boils down to 'same as'
some known liquid I guess.

Then again, in a hot atty, it's not the same as the temperature when you mixed it...

 

[MaxUT]

Here's the cheapest flow cup I could find:

PAINT VISCOSITY CUP from Aircraft Spruce

It's for automotive and aircraft paint, so it might just work with e-liquid.

 

[Marctwo]

I finally decided to have a little go at some timing while I was mixing up some new base.

Water is just too fast to use as a flow scale so I timed some Dekang 24mg unflavoured and matched it with glycerine and distilled water mixed at 11:2 respectively.

I'd be interested to know what others familiar with these bases think of this ratio...

 

[TJoe]

Rocketman where can I buy that syringe?
Thats a nice mixing setup.

 

[Marctwo]

I've tested flowrates now with 2 different setups, both giving pretty much the same results.

First I measured the flowrate of 24mg, unflavoured Dekang juice. This gives me a time scale and calibrates my setup to the DK scale. This time (T1) = 1DK.

Now that my setup is calibrated, I can go on to measure the flowrates of other mixes relative to the Dekang juice. If you don't use Dekang juice you can calibrate to this scale with VG/H2O mixed at 11:2 as mentioned in my previous post.

I timed some VG/H2O mixed at 5:1.
I then divided the time by my original calibration time (T1) which gives me the flowrate relative to Dekang.
The flowrate for this mix was 0.73DK.
This is by no means acurate to 0.01DK... but looks better.

I also measured some OK Smokey Liquid Gold 38mg at 1.14DK.

H2O is to fast to get a useful measurement on my setups but it's around 0.14DK...ish.

That's it. So I'd still be interested to see how acurately this could be replicated by others...

 

[Rocketman]

Sorry I didn't keep up with this thread, I am just not too good navigating this forum (way too big for me).
The needle/syringe I used came off of ebay, and is used for ink cart refilling. Maybe pretty standard. I just love the +/-0.01DK tolerance.

That's exactly what I do, compare it to the juice that seems to do OK, not too leaky, not to thick.

Temperature of the juice will matter. If you use a "big" cart then the cart will warm up with vaping and the juice will thin and run. Thicker at first, thinner as you vape. So, 0.95 to 1.2 DK for big carts (like the 808D-1). A little 510 or 401 cart has trouble wicking, so 0.7 DK (pretty thin really) to 0.95 DK would wick better.

Also remember we are approaching warmer weather and may have to adjust to a "Summer Blend".

Rocket,
the OCD PosterChild

 

[Switched]

Here's the cheapest flow cup I could find:

PAINT VISCOSITY CUP from Aircraft Spruce

It's for automotive and aircraft paint, so it might just work with e-liquid.

Nice tool but a little useless and pricey for what we do. A graduated 10ml syringe, with or without a blunt needle works better and goes for $0.80 each at Happy Vaper - Canadian Quality Electronic Cigarette/Personal Vaporizers and DIY Smoke Liquid

I love this thread and have it bookmarked for future use.

 

[Rocketman]

A constant cross section for a length of about 20 diameter is enough to ensure cylindrical laminar flow. This would widen the operating range and stabilize operation. The ink refill syringe and needle would also reduce impact of column height so you could operate over most of the 10ml length.
Allow the flow to stabilize for about a ml then take timed readings for each of the next several ml.

I started with PG (before it absorbed a lot of water vapor from the air) and VG.
Diluted with 10% 20% 50% DM water and compared the "curves" not actual values with published charts and WOW, pretty good match.

This seems to be so repeatable that I thin each little batch I mix based on a 90 sec/ml@70degF drop time using this device. Doesn't take much thinner (151 light rum, or sugarless Redbull drink) to thin e-juice. It you do it after mixing it will reduce you NIC content slightly. Sometimes I have to thin my 12mg/ml mix and I end up with 11.5.
Darn

Rocket

 

[Ralph T]

A constant cross section for a length of about 20 diameter is enough to ensure cylindrical laminar flow. This would widen the operating range and stabilize operation. The ink refill syringe and needle would also reduce impact of column height so you could operate over most of the 10ml length.
Allow the flow to stabilize for about a ml then take timed readings for each of the next several ml.

I started with PG (before it absorbed a lot of water vapor from the air) and VG.
Diluted with 10% 20% 50% DM water and compared the "curves" not actual values with published charts and WOW, pretty good match.

This seems to be so repeatable that I thin each little batch I mix based on a 90 sec/ml@70degF drop time using this device. Doesn't take much thinner (151 light rum, or sugarless Redbull drink) to thin e-juice. It you do it after mixing it will reduce you NIC content slightly. Sometimes I have to thin my 12mg/ml mix and I end up with 11.5.
Darn

Rocket

I feel bad for neglecting this thread. I have been consumed elsewhere. Kind of lost interest in pursuing this one because a). I switched to carto's mostly and b). I discovered this method which has solved my cart mod woes, (thanks to highping).

However, it is great to see several brilliant minds tackling the original question!

 

[arthrog]

I have a brookfield and a Hercules, do you want high and low shear?