Weight VS Volume


Mixing by weight is evangelised almost as much as reading the sidebar. I’ll try to do two things in this write up that I’m guaranteed to fail at: Try to remain impartial and try not to rehash too much of Botboy’s Guide to Mixing By Weight.

But here’s the problem; Mixing by weight is not intuitive, volume is. Hell, even mixing by drops is more intuitive than mixing by weight. And what I mean by intuitive is that when you think of liquids you don’t think of weight, you naturally think of volume. It makes sense that people would follow their intuitions, but there’s another way…

In fact, there are at least two ways of mixing by weight: There is the one that makes people think it’s overly complicated and confusing (the only one I’ve seen people gripe about) and the very simple way that most people do it. I say most people because I know a lot of DIY’ers and know very few that take the complicated route. What route is that? Specific Gravities for every flavor.

Allow me to climb up on my soap box for a second: If you’re using SG and sharing your recipes with the public STOP IT or, more reasonably, please share that information in the description. Because the rest of us, the majority, the lazy consensus, just use 1:1. While there is variance in flavor density, the difference is nominal and makes absolutely no difference when everyone agrees to use 1:1. If I mix a recipe that way and share it, the only way you won’t have the same results is if you use SG. If you mix a recipe with SG the only way anyone will have the same results is if they use the same SG that you’re using. And depending on where you find your SG, or how you go about measuring it yourself, there will be variations.

Stepping down now, feel free to tear apart my argument.

But before you do, let me illustrate the numbers and see how close we get to being 100% accurate using 1g = 1ml

Let’s use Mother of Dragons’ Milk as an example to see how using or not using SG affects the outcome as you scale a recipe.

30ml

Flavor%gramsSG
TFA Bavarian Cream20.600.64
TFA Dragonfruit72.102.15
TFA Strawberry (Ripe)20.600.62
TFA Vanilla Swirl20.600.63
Totals133.94.04

As you can see, the total flavoring you would add for a 30ml would be 3.9g vs the SG total of 4.04. i.e. 3.9g is 96.53% accurate.

120ml

Flavor%gramsSG
TFA Bavarian Cream22.42.56
TFA Dragonfruit78.48.6
TFA Strawberry (Ripe)22.42.49
TFA Vanilla Swirl22.42.52
Totals1315.616.17

96.47% accurate

240ml

Flavor%gramsSG
TFA Bavarian Cream24.85.13
TFA Dragonfruit716.817.2
TFA Strawberry (Ripe)24.84.98
TFA Vanilla Swirl24.85.04
Totals1331.232.35

96.44% accurate

Accuracy

As you can see from the example of scaling a recipe up without SG you’ll get about 3-3.5% from 100% accuracy until you get over 500ml. A nice compromise between the SG fanatics and the lazy “one to one” approach is considering all your flavors to be the same weight as PG, but the difference is nominal and I’m personally ok with an accuracy score of 97%.

But what about volume? There are a lot of things I could criticize about mixing by volume (I’ll get to those) but accuracy is not one of them. Even if you’re really good at reading the meniscus on a syringe, and have accounted for the variation in volume due to temperature it’s likely that you’re still not going to hit 100% accuracy but it’s entirely plausible that you’ll be closer.

Regardless of which method you choose, consistency is key. This is why #teamsyringe and #teamscale can both unite against those who mix by drops.

Workflow

I started mixing by weight in 2015 and it was around 2011 that I bought my first DIY supplies. I spent a shamefully long time, starting out, eyeballing my mixes and occasionally counting the drops in order to be “more accurate” when writing down my terrible recipes. All this is to say I have a decent amount of experience mixing by volume and weight. The key difference, at least for me, was how it changed the way I approached mixing. Before mixing by weight I still enjoyed sitting down to mix but there was an aspect of it that seemed like a chore.

For example, when mixing by volume I’d see the latest hyped 8-10 ingredient recipe and, of course, feel compelled to mix it up. Grab a bottle, collect up all the necessary flavors (minus the one to five I’m missing) and then set my syringes out. After that I would take all the bottles that had tips (most of them) and pry those bastards off so I could get my syringe in there. One syringe for each flavor or a little cup of water to clear the syringe out after each flavor and I’m on my way. After all the flavors were added I would grab a syringe for PG, add that and then use it for the nicotine. Then, finally, move on to the dreaded process of sucking up VG into a syringe (eventually settling for less accuracy and just pouring that viscous nonsense straight into the bottle) And after all of that I would bring all my used syringes to the kitchen and clean them up, being careful not to rub the markings off.

But then, after discovering mixing by weight: Grab a bottle, set it on the scale, and gather the necessary flavors. Add flavor 1, tare, add flavor two, tare, etc. Add PG, VG, and nic into the bottle, taring after each and then cap it. Done. Nothing left to clean, no tips to snap back on the flavoring bottles. Faster, cleaner and more fun.

How’s that for unbiased?

Ultimately it boils down to personal preference. I haven’t seen very many “I mix by volume and I think mixing by weight is pointless” counter arguments and definitely haven’t found a compelling reason to switch back. But I have seen a few reasons that keep people mixing by volume like:

  • Large batches
  • Small variety of mixes
  • Habit
  • Add yours in the comments…

If you’re mixing by the liter or more, first of all, this entire write up isn’t for you and second, keep doing what works for you. Keep doing what works either way, it’s entirely subjective and while I won’t stop evangelizing for the scale, I don’t actually care if I convert the masses.