About mixing formulas and exactitude

[pwmeek]

(Began as a reply in another part of the ECF forums; slightly modified here)
Mixing is good. My own e-juice calculator is just doing the calculations in my head (or with a standard calculator) with a few notes on paper. Because of this, I strive to end up with juice formulas as simple as I can make them. My current "formula" is two parts of a weak nic base mixed with one part of a stronger nic base. It's hard to get much more simple than that.

My own e-juice is very strong (65 mg/ml in 68/32 PG/VG), so yours might be something more like one part nic base, 4 parts PG and 5 parts VG. I find that the actual PG/VG ratio is really not very critical, so if you have found that you like mostly-VG juices, then probably anything between 60% and 80% VG will work for you. This lets you choose an easy-to-mix formula that ends up anywhere in that range.

Nicotine content is likely a little more critical, especially if you want fairly low amounts of nicotine. Still, if you are aiming for 12 mg/ml (for example) you will probably be able to use anything from 10 to 14 mg/ml (roughly plus or minus 15%). Again, this lets you choose a mixing formula that is less complicated than some "exact" formula that calls for mixing 13.243574 ml of PG plus 47.9846584 ml of VG and 4.73642 ml of nic base.

If you like e-juice that is mostly one or the other of PG or VG, consider getting your nic-base in the carrier that you want the least of in your final formula. For instance, if you want to end up with 10 mg/ml nicotine and 90% VG, get your nic base as 100 mg/ml nicotine in 100% PG. Then you would just have to mix one part of your nic base with nine parts VG, and voila! there is your e-juice with an easy to mix formula. You could use the same method to end up with 20 mg/ml nicotine and 80% VG by mixing at one to four.

My point is: it is MUCH more important to end up with a simple formula than it is to hit some exact PG/VG ratio and nic strength. For one thing it will make it MUCH less likely that you will make a mistake while mixing that means you have to toss a batch of juice, or (worse) maybe spend a few weeks wondering why vaping is not satisfying your nic craving (or maybe making you slightly nic-sick for those weeks).

As far as mixing by weight vs mixing by volume: PG, VG, and nicotine are all close enough to 1 gram/ml (SG of near 1.0) that it makes little difference, especially if you take my suggestion that exact ratios are fairly unimportant. What you are aiming for is a simple to mix formula that works for you. What do you care about exact numbers as long as you are satisfied by your result? And that you can mix it week after week, month after month, without making mistakes or sweating over amounts (or weights) too small to really matter.

 

[NGAHaze]

If it works for you that's fine however I'd hesitate to offer this as generally good advice for most.

One glaring issue I saw with your post is your contention that 'PG, VG, and nicotine are all close enough to 1 gram/ml (SG of near 1.0)' which is simply not the case. The SG of VG is 1.26g and accordingly, the SG of your Nic will vary depending on the strength and the subsequent carrier being used, VG, PG or a combination of the the two. That's a pretty significant difference if you ask me. If you had to pay more than 25% additionally in taxes from what you already pay for example, I imagine you'd notice it pretty quickly.

Besides, it's really simple to utilize one of the many widely available e-juice calculators out there so why bother relying on just 'ball-parking' it.

 

[DaveP]

PWMeek, I agree with you on some/most of the points you made. Mixing by weight is my "easy" way to maintain repeatability. Some DIYers have marks on Erlenmeyer flasks and various jars and containers. What counts is that you are able to accurately repeat the mix that you intended to make.

I like BotBoy's mixing by weight blog for my DIY reference.
Botboy141 Guide to Mixing By Weight • r/DIY_eJuice

I agree with NGAHaze that VG is considerably greater than 1 gm/ml.

The basic values that you need to know for mixing by weight are below.

• Weight of PG: 1.038 grams per ml
• Weight of VG: 1.26 grams per ml
• Weight of Pure Nicotine: 1.01 grams per ml
  
  
• Weight of 100mg in PG: 1.035 grams per ml
  
  
• Weight of 60mg in PG: 1.03632 grams per ml
  
  
• Weight of 50mg in PG: 1.0366 grams per ml
  
  
• Weight of 48mg in PG: 1.036656 grams per ml
  
  
• Weight of 36mg in PG: 1.036992 grams per ml
  
  
• Weight of 24mg in PG: 1.037328 grams per ml
  
  
• Weight of 100mg in VG: 1.235 grams per ml
  
  
• Weight of 60mg in VG: 1.245 grams per ml
  
  
• Weight of 50mg in VG: 1.2475 grams per ml
  
  
• Weight of 48mg in VG: 1.248 grams per ml
  
  
• Weight of 36mg in VG: 1.251 grams per ml
  
  
• Weight of 24mg in VG: 1.254 grams per ml

What matters is that you can repeat that great recipe over and over with whatever method you choose.

 

[stols001]

I sort of don't agree with this myself. For one, I find it easiest (and most repeatable) to use the same strength nicotine in my mixes, not combining some frankenstin-ish nicotinic base monstrosity and having to deal with THAT.

It is also neither the easiest nor most inexpensive way to buy nicotine, or to store it if you have any worry about FDA regulation approaching whatsoever. I'm not going to want anything other than 100 mg/ml in my refrigerator. PG and VG DO matter, especially if a person is sensitive to one or the other.

I highly doubt that I would continue vaping "for weeks" on nicotine that made me nic sick, I would start to wonder what was up with one of my mixes if that happened, probably the FIRST time I vaped it if it was too strong.

Finally, I do think that there is some room for mixing "errors" without much harm, but I don't set out with the idea that it's all a vague nebulous concept, and that it's fine to just mix up a bunch of stuff knowing I'm "in the area." I like precision, as then I can repeat my results. I'm certain that (as an at home mixer) perhaps my "precision" may be a little different from commercially made e-liquid, but I strive for the best that I can get so that if I like a mix, I can repeat it. With that said, I'm quite sure that there has been some variation in my mixes (that I can live with) and I'd say that is probably true for many. I'm mixing and measuring by hand, not machine, and well.... But I do think being precise is a good option.

With that said, the beauty of DIY is that you can do what works for YOU, but I am not sure I would present it as the "best" method for everyone, as it most certainly isn't going to be. Equally, my methods may not work for everyone, but they do work for me and I did take heed of many others in the DIY section because I WANTED excellent, precise results, and those strategies (along with so much more information) is available to anyone.

I guess part of it may come down to what DIY means to them, and for me, DIY means freedom from regulation (at this time) lower prices, and most important of all, *I* am enjoying my results.

Good luck,

Anna

 

[Letitia]

Your nic intake is much higher than most so perhaps a couple of percentages off will be relatively unnoticeable. At lower nic levels just one percent will make a difference. Just playing around with my base mix I notice changes in flavor and steeping time. While I envy the fact a simple mixing formula works for some, don't see it working out for me in particular.

 

[zoiDman]

(Began as a reply in another part of the ECF forums; slightly modified here)
Mixing is good. My own e-juice calculator is just doing the calculations in my head (or with a standard calculator) with a few notes on paper. Because of this, I strive to end up with juice formulas as simple as I can make them. My current "formula" is two parts of a weak nic base mixed with one part of a stronger nic base. It's hard to get much more simple than that.

My own e-juice is very strong (65 mg/ml in 68/32 PG/VG), so yours might be something more like one part nic base, 4 parts PG and 5 parts VG. I find that the actual PG/VG ratio is really not very critical, so if you have found that you like mostly-VG juices, then probably anything between 60% and 80% VG will work for you. This lets you choose an easy-to-mix formula that ends up anywhere in that range.

Nicotine content is likely a little more critical, especially if you want fairly low amounts of nicotine. Still, if you are aiming for 12 mg/ml (for example) you will probably be able to use anything from 10 to 14 mg/ml (roughly plus or minus 15%). Again, this lets you choose a mixing formula that is less complicated than some "exact" formula that calls for mixing 13.243574 ml of PG plus 47.9846584 ml of VG and 4.73642 ml of nic base.

If you like e-juice that is mostly one or the other of PG or VG, consider getting your nic-base in the carrier that you want the least of in your final formula. For instance, if you want to end up with 10 mg/ml nicotine and 90% VG, get your nic base as 100 mg/ml nicotine in 100% PG. Then you would just have to mix one part of your nic base with nine parts VG, and voila! there is your e-juice with an easy to mix formula. You could use the same method to end up with 20 mg/ml nicotine and 80% VG by mixing at one to four.

My point is: it is MUCH more important to end up with a simple formula than it is to hit some exact PG/VG ratio and nic strength. For one thing it will make it MUCH less likely that you will make a mistake while mixing that means you have to toss a batch of juice, or (worse) maybe spend a few weeks wondering why vaping is not satisfying your nic craving (or maybe making you slightly nic-sick for those weeks).

As far as mixing by weight vs mixing by volume: PG, VG, and nicotine are all close enough to 1 gram/ml (SG of near 1.0) that it makes little difference, especially if you take my suggestion that exact ratios are fairly unimportant. What you are aiming for is a simple to mix formula that works for you. What do you care about exact numbers as long as you are satisfied by your result? And that you can mix it week after week, month after month, without making mistakes or sweating over amounts (or weights) too small to really matter.

I agree with some of what you say.

And believe that Many who DIY Needlessly Overcomplicate things by trying to obtain Measurements that Far Exceed their ability to taste the difference. And or work with Significant Digits of Numerical Values that I question their Ability to achieve.

That said, I believe the Most Important thing about doing DIY is Repeatability.

Because a Recipe Isn't much good if you Can't make it Twice. And it is Exceedingly Difficult sometimes to do a New Flavor Workup or Troubleshoot when you Don't Know very closely what you have.

There is also the Concept of Varying Degrees of Accuracy. That is, different Parts of a Mix can have Different Levels of Numerical Accuracy to an Arbitrary Value and still be perceived as having the Same Taste to the average person.

Here is an Example...

It kinda Depends on what I'm Measuring.

For measuring 100mg/ml Nicotine Base to make "Pre-Mix", a Line on a 250ml Bottle is Enough.

For measuring VG and PG to add to my 250ml Pre-Mix Bottle, a Graduated Cylinder is Fine.

For Measuring Flavoring to be added with the Pre-Mix, a Scale (to me) is Hard to Beat.

How do you prefer to mea sure your recipe?

Applying the Last Measuring Technique (with it subsequence accuracy) to the first example of making Pre-Mix isn't going to hurt anything. But it really Isn't Necessary to achieve such Numerical Precision.

But using the First Measuring Technique to Measure Flavoring would make it all most Impossible to achieve Repeatability from Batch to Batch.

 

[englishmick]

I made up a spreadsheet for mixing. I enter the size of the bottle. The spreadsheet takes the % of each flavoring and converts it to mls. And it subtracts the total amount of flavoring from the bottle size and tells me how much base to add.

I make base at 10% with 70 VG 30 PG. My spreadsheet doesn't worry about that so the final percentages of nic and PG/VG depends on how much flavoring the mix has. I add the base using a graduated cylinder which is a little inaccurate anyway since some liquid gets left in the cylinder.

It's not super accurate, but it's simple. And I guess it's repeatable, gives the same inaccuracies each time I make a particular recipe. Works for me. I don't think I would notice a difference if I ensured each recipe had exactly the right % of PG and nic and so forth.​

 

[DaveP]

And believe that Many who DIY Needlessly Overcomplicate things by trying to obtain Measurements that Far Exceed their ability to taste the difference. And or work with Significant Digits of Numerical Values that I question their Ability to achieve.

That said, I believe the Most Important thing about doing DIY is Repeatability.

My thoughts exactly. I'd say that on the average I tend to add nicotine a few drops on the high side of my recipe. If my dropper contains a little more it usually goes into the bottle. Plus or minus a few drops in a 50ml mix is good for the soul! So what if my recipe calls for 1.5mg and I end up with 1.58mg just cause it was left in the dropper when the 1.5mg was achieved? Who cares if my 3mg/ml recipe is 3.2mg/ml?

I'm a little stingier with flavor and try to get that nailed. More is not always better once the recipe is honed to the "just right" point.

Pg and Vg aren't that critical. The condiment squeeze bottle occasionally refuses to stop on command and I end up with "Good enough for government work". Do I really care if my 60/40 is really 62/38 in that particular bottle?

 

[zoiDman]

My thoughts exactly. I'd say that on the average I tend to add nicotine a few drops on the high side of my recipe. If my dropper contains a little more it usually goes into the bottle. Plus or minus a few drops in a 50ml mix is good for the soul! So what if my recipe calls for 1.5mg and I end up with 1.58mg just cause it was left in the dropper when the 1.5mg was achieved? Who cares if my 3mg/ml recipe is 3.2mg/ml?

I'm a little stingier with flavor and try to get that nailed. More is not always better once the recipe is honed to the "just right" point.

Pg and Vg aren't that critical. The condiment squeeze bottle occasionally refuses to stop on command and I end up with "Good enough for government work". Do I really care if my 60/40 is really 62/38 in that particular bottle?

I agree.

I Can't Taste the Difference between 78.347% VG to 21.653% PG verses 80% VG to 20%. And 80% VG to 20% PG were arbitrarily chosen anyway because they are "round numbers" that are multiple of 5.

But I many times can Taste the difference when my Flavoring(s) differ by 1% or more. Sometimes at Less than 1% depending on the Flavoring(s).

Not say'n this is Always a Bad Thing. And I have made many Mixes over the Years by Bending the Initial Percentages one way or another.

But when I got to something I really Liked, and the Tweaking was over, I wanted to be able to Replicate it Exactly.

 

[Letitia]

I don't generally use pg. I mix 3% dw, falvors, and nic, then fill vg. I seldom measure vg in smaller bottles.

 

[DaveP]

I don't generally use pg. I mix 3% dw, falvors, and nic, then fill vg. I seldom measure vg in smaller bottles.

Some people are sensitive to PG throat hit. I sense it, but I've slowly gone from 90pg/10vg (long ago) down to 60pg/40vg and sometimes 50/50. I'm finding that 50/50 is a good place just because a quart of PG and VG are empty at the same point, not counting the PG in most flavors throwing the mix off a tad.

 

[pwmeek]

It is important that you be able to mix your desired juice time after time without major errors. My contention is that by working out simple formulas that come close to some number (my PG/VG ratio happens to be 68:32) makes it easy to remember, easy to measure, and hard to make a mistake. I didn't set out to mix my juice at 68:32; it just happened that an easy mix of two parts to one part (by volume) of my available nic bases calculated out to that ratio. (I use enough nicotine that it affects my PG/VG ratio significantly.) I knew from experimenting that I was happy with any ratio between 80:20 and 60:40 - plenty of PG for sensation/TH, but enough VG that I could see the vapor easily.

RE: percentage differences: A few percent difference in either PG/VG ratio or in nicotine strength is not likely detectable by either sensation or effect. Note well: The percentage difference between 6 mg/ml (0.6%) and 12 mg/ml (1.2%) is 100% not 6% (and certainly not 0.6%). A 10% difference from 6 mg/ml is either 5.4 mg/ml or 6.6 mg/ml; I doubt that anyone could tell the difference by either taste or effect. (The PG carrier in most flavorings as a tiny component of a final mix aiming for zero PG might be an issue for the rare person with a severe PG sensitivity problem.)

I am (and was) aware that VG is slightly higher SG (about 1.25) but my point was that the exact numbers are not the important thing about DIY mixes; the important thing is how the resulting mix works for you. Mixing by volume (which incidentally is how nicotine strengths are specified and sold by any DIY suppliers I am aware of) just makes my calculations easier.

As for vaping a juice that makes you nic-sick (slightly and occasionally), vaping is self-titrating - you vape more or less depending on how much your system desires nicotine. I was once distracted during a mixing session and ended up with undiluted nic base (100 mg/ml in 100% PG) in my ready-use bottle. (I no longer allow people to interrupt me when mixing. "Is the house on fire? No? Go away.") The first session (like most vapers, I take a series of puffs and wait a while before another session of puffs) was quite a shock. It made me dizzy and a bit queasy; I normally use 65 mg/ml so this was around 50% stronger than my usual. I realized what must have happened and tried a single short puff for my next session - not quite enough. A longer puff; still not enough. I finally determined that at this strength, two medium puffs did the job. The problem was that my usual method was 3-4 medium puffs (3-5 seconds each); it was just too easy to over-puff if I was thinking about something else. I also didn't like the wispy vapor from straight PG. After I used up the overstrength juice (a week or so) I went back to mixing at 65 mg/ml.

 

[pwmeek]

<snip>not combining some frankenstin-ish nicotinic base monstrosity and having to deal with THAT.<snip>
Anna

I think you may have misunderstood. That is not a mixed up base from which I then mix an e-juice. That is what I vape. I mix one part of 100 mg/ml nicotine in pure PG (from my old supply) with two parts 50 mg/ml nicotine in 50:50 PG/VG (my most recent supply of nic base). This makes up my current version of e-juice: 65 mg/ml nicotine in 68:32 PG/VG. These numbers are not some carefully-chosen magic numbers, they are just what results from my easy-to-mix-and-remember two to one formula and reasonably close to my intended strength and ratio. (That said, by most standards my e-juice is possibly a bit frankenstein-ish. In fairness, I was a monster smoker - 4 PPD unfiltered plus a can of snus - before I quit over six years ago.)

I began experimenting with high nicotine levels when I got tired of chain vaping; I used to have a rig in hand (actually rotating between three rigs to avoid the rigs getting so hot they burned my hands and lips) my entire waking hours and at hourly intervals all night. I now can get along with a few puffs every 20-30 minutes, and have found that I now consume less nicotine per day than when I was vaping weaker juice (36 mg/ml). I can now also go without vaping for several hours with only mild discomfort.

I haven't used any flavorings in my juice for several years. I discovered that I didn't miss flavoring while experimenting with nic levels and PG/VG ratios. Fortunately this coincided with my growing suspicion that flavorings might just be the most hazardous part of vaping. They certainly cause premature wick failure, My atomizers now last six months or more with no maintenance.

 

[pwmeek]

But I many times can Taste the difference when my Flavoring(s) differ by 1% or more. Sometimes at Less than 1% depending on the Flavoring(s).

If you consider the difference between 2% and 3% to be 1% then there is a problem in definition. I would consider that a 50% increase in flavoring. Huge difference and maybe even enough to spoil a whole batch of e-juice.

Now I suspect that you would have some difficulty in detecting (or measuring) the difference between 2% and 2.02% flavoring which is a 1% increase. I don't use any flavorings; I'm only vaping for the nicotine. (I do like my TH, though.)

 

[zoiDman]

If you consider the difference between 2% and 3% to be 1% then there is a problem in definition. I would consider that a 50% increase in flavoring. Huge difference and maybe even enough to spoil a whole batch of e-juice.

Now I suspect that you would have some difficulty in detecting (or measuring) the difference between 2% and 2.02% flavoring which is a 1% increase. I don't use any flavorings; I'm only vaping for the nicotine. (I do like my TH, though.)

Since Flavoring Percentages used in DIY are always expressed as being the Percentage of the Total Volume, I didn't think there was a need to Express it any other way.

And you are Right, I would probably have a Hard Time tasting the difference between Flavoring at 2% or 2.02%

Something I mentioned in the 2nd and 3rd Sentence of Post #6.

 

[440BB]

I've been making the same monthly batch of our ADV for a couple years, about 375ml, 2/3 PG 1/3 VG, 8% flavoring and about 8mg. That works out to 30ml 100mg PG, 30ml flavoring PG, 190ml PG and 125ml VG. Easy as can be.

I got interrupted in the middle of making my last batch and ended up at 12mg. Instead of mixing it down to 8mg, we decided that with the holiday stress and more stealth vaping while visiting maybe 12mg would be a good thing. I noticed a bit more tingle and that we vaped quite a bit less over the last few days. That interruption may lead us to moving back up to 12mg!

Our nic level only went up by .4% but it sure felt like a 50% increase to me.

 

[pwmeek]

I've been making the same monthly batch of our ADV for a couple years, about 375ml, 2/3 PG 1/3 VG, 8% flavoring and about 8mg. That works out to 30ml 100mg PG, 30ml flavoring PG, 190ml PG and 125ml VG. Easy as can be.

I got interrupted in the middle of making my last batch and ended up at 12mg. Instead of mixing it down to 8mg, we decided that with the holiday stress and more stealth vaping while visiting maybe 12mg would be a good thing. I noticed a bit more tingle and that we vaped quite a bit less over the last few days. That interruption may lead us to moving back up to 12mg!

Our nic level only went up by .4% but it sure felt like a 50% increase to me.

It was a 50% increase in nicotine.

In any given milliliter of juice there used to be 8 milligrams of nicotine; then there were 12 milligrams. That makes a change of 4 milligrams. 4 divided by 8 equals 0.5

0.5 is just another way of saying 50% (you multiply by 100 to get percent). There was an increase of 50% over the original amount of nicotine. 12 is 150% of 8. This is a major increase in nic level.

That said, I truly believe that people who are vaping for the nicotine frequently vape at sub-optimally low nic levels. If you feel compelled to chain vape, you are probably vaping at too low a level.

 

[440BB]

Guess my sarcasm was a little too subtle...

 

[pwmeek]

Since Flavoring Percentages used in DIY are always expressed as being the Percentage of the Total Volume, I didn't think there was a need to Express it any other way.

Yes; express the level as a percentage. BUT !!! express the CHANGE as the difference between the old percentage and the new percentage as a percentage. (3% is 150% of 2%)

 

[pwmeek]

Guess my sarcasm was a little too subtle...

Maybe it was. (But maybe it was too subtle for more people than me. Getting math right is important to get straight for DIYers. I tend to take statements of importance literally.)