Combined Viscosity of PG/VG Mixes

[spawn]

Hi, thought I'd share a bit of work I did recently around calculating the viscosity of PG/VG mixes.

Some background: I've been using a 60PG/40VG mix for some time and decided to go for more VG (more vapour / less throat hit) and mixed up a 50/50 mix. I found that the solution was far too thick (viscous) to wick decently in my rta (fogger v4/5). I needed to add some water (distilled water) (other options are PGA/Vodka but I haven't explored those - too expensive).

I researched viscosity of PG and VG, including dilutions of VG with water. I then came across a formula for determining the viscosity of solution using the viscosity of each component. Using this I created a spreadsheet that one can use to determine the correct amount of water to add in order to obtain the desired viscosity. In my case I aim for that of a 60PG/40VG solution.

To use the spreadsheet, change the values of B2 and B7. The current spreadsheet is set for 12% DW (distilled water) and 70%. The calculations are based also on the excellent spreadsheet I found on ECF: ejuce_calculatorv13.xls (sticky in this forum).

I have mixed up a batch as per the spreadsheet and it seems to be right - I'm getting decent wicking and no leaking with a 70% (+12% DW) mix as per the values in the 'sheet.

Anyway, enjoy. I hope someone finds this useful.

(Update)
Please note:

The calculations assume the flavor is PG based, I have two ADVs, the first using a very concentrated flavor mix (my own ) at only 2.3% of the solution, visually it appears to have the viscosity of PG but at the small percentage it doesn't make too much difference if this is wrong. I have another flavor mix (also mine) that is watermelon (high concentration - alcohol based at recommended 1%) with TFA Iced Tea which is around 20%, the TFA Iced Tea appears to be very 'watery' so I adjusted the formula to assume water viscosity for the flavor mix which is 12.6% of the total. In this case, using the spreadsheet, I don't need to use any DW to get the viscosity right.

So, just be aware of this, it is the only difficult part of the calculations as the flavor viscosity has to be assumed.

If you want to change the viscosity calculation to use DW instead of PG, change B13's formula from:

=B12*B4+C12*C4+B11*C4

to:

=B12*B4+C12*C4+B11*K2

 

[Alien Traveler]

For me 30/70 pg/vg was good for fogger. Depends a lot on wicking.
90% vg and 10% water (no flavoring, some call it "pure vg") works for me with protank coils.

It is difficult to find universal best viscosity. Besides, viscosity is only one of the important parameters; others may include temperature and wettability.

EDIT: Thanks for interesting data. I did not suspect of so huge drop of viscosity from 90% to 85%.

 

[Exchaner]

Hey guys thanks for your input on this topic. I am trying to figure out how much DW is needed to thin out VG to the same viscosity as PG. Any help with that? I am too dense to understand the spread sheet. I normally use 40% PG, 3.2% DW, 57% VG. That translates to thinning the VG by 5.6% (3.2/57=5.6)

 

[dannyv45]

It really depends on the device your vaping with, some hardware will vape VG well and others will cause dry hits. You just need to experiment. There's no set rule. Add in 1% increments until there are no dry hits and good flavor production and cloud plume is produced. I use 6% for an 80vg/20pg mix in my kayfun. If your still not wicking at 5.6% maybe you need to go to 7%. Just keep working upward in 1% increments until you get to where you need to be.

 

[Exchaner]

Thanks Danny, but I am using DW not for wicking purposes but for improving throat hit in a carto. It definitely does help by giving the vape a crisp sharp feel. The trick is how much DW to use before the juice gets too thin and therefore vaporizes too fast. I have decent results with the ratios I gave above but I will take your advice and increase a bit to see how far I can push the limit.

 

[dannyv45]

Thanks Danny, but I am using DW not for wicking purposes but for improving throat hit in a carto. It definitely does help by giving the vape a crisp sharp feel. The trick is how much DW to use before the juice gets too thin and therefore vaporizes too fast. I have descent results with the ratios I gave above but I will take your advice and increase a bit to see how far I can push the limit.

If it's smoothness your trying for, some people have used saline instead of DW and report more smoothness then just plain DW. I myself tried both and never noticed a difference with smoothness and throat irritation. What worked for me was reducing nicotine a few MG. I find when I went from 18 to 12mg it made a huge difference and I never had any issues with nicotine urges.

 

[spawn]

Hey guys thanks for your input on this topic. I am trying to figure out how much DW is needed to thin out VG to the same viscosity as PG. Any help with that? I am too dense to understand the spread sheet. I normally use 40% PG, 3.2% DW, 57% VG. That translates to thinning the VG by 5.6% (3.2/57=5.6)

It's just over 20% DW from the table in the spreadsheet but I don't think you'd want to go that far. You'd have the effective viscosity of PG for the entire solution which I would think would be too thin in most cases.

Like most have said, it depends on build, wick, device (RBA etc), you have to work out what works for you. The spreadsheet just helps figure it out if you have a starting point already. So, for example, in my case, I found that on the fogger a 60PG/40VG solution worked well so when increasing the amount of VG I aimed for the same viscosity.

 

[Exchaner]

It's just over 20% DW from the table in the spreadsheet but I don't think you'd want to go that far. You'd have the effective viscosity of PG for the entire solution which I would think would be too thin in most cases.

I actually think 20% might work because some vendors are using that much DW in their VG liquids; Mt Baker Vapor for one.

 

[spawn]

Just one thing to note when using this (I'll update the O.P. too), the calculations assume the flavor is PG based, I have two ADVs, the first using a very concentrated flavor mix (my own ) at only 2.3% of the solution, visually it appears to have the viscosity of PG but at the small percentage it doesn't make too much difference if this is wrong. I have another flavor mix (also mine) that is watermelon (high concentration - alcohol based at recommended 1%) with TFA Iced Tea which is around 20%, the TFA Iced Tea appears to be very 'watery' so I adjusted the formula to assume water viscosity for the flavor mix which is 12.6% of the total. In this case, using the spreadsheet, I don't need to use any DW to get the viscosity right.

So, just be aware of this, it is the only difficult part of the calculations as the flavor viscosity has to be assumed.

If you want to change the viscosity calculation to use DW instead of PG, change B13's formula from:

=B12*B4+C12*C4+B11*C4

to:

=B12*B4+C12*C4+B11*K2