Howdy boys and girls,
I'm going to jump right into this one today since I have once again waited till the very last second to write it.
Today, we are going to talk about measuring by weight versus measuring by volume. Anyone who follows me should know I am very formed in my opinion on this topic, but for the sake of science, I will be as neutral as possible through the analysis.
#Measuring by Volume
This is how almost everyone starts mixing. It's easy to understand and very intrinsic. We are taught at a young age that liquids get measured by volume.
There are all sorts of little devices to help us keep track of volume in the mixing world. Flasks, graduated cylinders, bottles measured in milliliters, syringes of all sizes, and so on. It's easy to understand and easy to get started.
Then when it comes to mixing your juice, you plug in the percentage of the flavor you want to use, then the ejuice calculator spits out the volume you need. You don't question it, you just accept the value it's given you. I would be lying if I said I didn't start by measuring by volume as well for these very same reasons. It just makes sense.
With that said, I don't feel like I need to explain this process any more than I just have. If you clicked this article, you probably have a grasp on this mixing method already. If you don't, there are plenty of YouTube videos and links in the sidebar to get you started.
As for some of the other modest benefits, it's cheaper to get started. $10 will buy you are large bundle of syringes in different sizes. You will need a lot. Ideally, a separate syringe for every flavor so there is no cross contamination of your flavors. Don't forget, you need some for PG/VG as well. And don't even think about using the same blunt tip needle you use for of PG and flavorings on VG. Get the biggest damn needle you can find.
So, to be blunt though, this method does have a load of negatives.
Since it requires you to mix with open tops, you are eventually going to spill something. Everytime you open a flavoring, this probability increases.
It's also slow. So very slow. You have to open the cap, set it aside, pick up your syringe, wait for the flavor to draw up, slow down as you get close to your mark, put the cap back on, dispense your flavoring, rinse out the syringe, etc, etc. Do you see where I'm going here? There's so many non-value added processes.
Lastly, there is some inaccuracy in measuring by volume. Is it enough to make a difference? That mostly depends on the concentrates you are using and batch size you are creating. If it's INW or MF in a 10ml batch, then absolutely. TFA or CAP in a 100ml batch, nope. The discrepancy comes from the fact that the blunt tip needle holds a certain amount of liquid that can go unaccounted for. So, without proper attention to that, you could potentially ruin smaller juice batches and testers.
Pros
- Easier to grasp and understand
- Smaller initial up front cost
- Can be quicker and more efficient for very large matches (1 liter+)
Cons
- Larger back end cost - you will be tied to buying more and more syringes. They don't last forever
- Slower mixing process
- Clean up takes a while and is an unnecessary headache
- Prone to spills
- Becomes more inaccurate the smaller the batch you create
#Measuring by Weight
Ok, so this is no where near as hard to grasp as you think it is. It's simple really.
- Determine what percentage of a flavor you want to use.
- Plug that percentage into the ejuice calculator.
- Read the weight measurement the ejuice calculator gives you.
- Put that much flavoring into mixing bottle.
These ejuice calculators take care of everything for you. You don't have to calculate specific gravity. You don't have to worry about the difference in weight of VG and PG. You don't have to worry about any of this. Someone else already done that work for you. The hardest thing you have to do is change your ejuice calculator to measure in weight, if it didn't have it by default. I suggest you watch Wayne's tutorial on mixing by weight if you are still having trouble with this concept.
So, some basic must do's.
Your scale. Pick up the AWS LB-501. There are other options out there, but this scale has a rather high capacity at 500g and measures down 0.01g. It's perfect for what we are doing, and with an average price of $25 on Amazon, it won't put a dent in your wallet.
Calibrate you scale often. I range from once a week to once a month. It depends on how much I've been mixing and if I notice the numbers to start seeming off (a drop usually weighs 0.025g. 4 drops equal 0.1g) This makes sure you are creating consistent product free of errors.
Buy your flavors from one of the golden three vendors - ECX, BCV, and GremlinDIY. All three of these companies distribute flavors that are sold in dropper bottles. They also all have supreme customer service and fast shipping. Dropper bottles are essential to getting the most out of mixing by weight. They let you dispense flavors straight from the bottle without taking the tip off. If you still have some flavors in vials or glass bottles, I highly suggest you just pick up a 1000 pack bag of mini pipettes and trash them after every use until you are done with those flavors.
As for your PG, VG, and nicotine, you will need to purchase (3) 8 to 16 oz LDPE wide mouth lab or condiment bottles. I got mine from Amazon for $3 each. They will last forever and allow you to dispense straight into your mixing bottle, just like your flavors. Try to get the smallest bottle possible that your can deal with for your nicotine. This will be your "working bottle" that you leave out most of the time. If you use too big of a bottle, you risk trashing some of your nicotine due to degradation and oxidation
Pros
- Faster mixing process. Take cap off, drip flavors into bottle, put cap back on. Done.
- No clean up. Unless you're a clumsy idiot like me and miss the hole altogether
- Cheaper in the long run. The scale quickly pays for itself since you no longer have to pay for syringes
- Accurate down to 0.01g. Take a second to think about just how freaking small that number is. That's the weight of a single grain of sand.
Cons
- Higher initial cost. This amount is so incredibly small though.
- Might take 15 minutes of reading to understand how to use the scale
#Mixing by Drops
No. Just no.
Stop what you are doing immediately and use a real method.
#Conclusion
Start measuring by weight. Unless you are mixing so much juice you could start your own company, there's zero benefit to mixing by volume. I've laid out the pros and cons pretty clearly.
You can find my previous articles over at /r/ModestMonday
Be sure to check out Matthew Kocanda, TheCatHimself, and myself tonight on BeginnerBlending at www.mixlr.com/inthemix-podcast where you can chat with is and we'll answer all your questions about measuring by weight and volume. Show starts around 9:15pm EST.
While not a huge variable at the scale and temperatures we're working at, another thing worth noting about accuracy and measuring method is that mass is constant, volume is not.
As temperature goes up liquid generally becomes less dense, meaning for a given mass the volume will increase.
EDIT: Removed this graph of PG density as it was hard to read and possibly inaccurate/incorrect.
so now we have to add a thermostat to the by-weight initial startup cost? ;)
Just thinking about if all liquids expand about equally, the ratio will be the same in the end. ;-)
Not all liquids change density at the same rate I believe.
Even if they did, you would need to ensure all the liquids are the same temperature when measuring them out.
This is why I said 'about equally', not equally.
But lets have a look at numbers:
Volumetric thermal expansion coefficient for glycerol [1]: 4.85 x 10^-4 1/K.
Volumetric thermal expansion coefficient for propylene glycol [2]: 7.3 x 10^-4 1/K.
So for your example there was a 1 % volume difference between 10 °C and 30 °C. The difference in volumetric expansion between propylene glycol and glycerol is 33 %, therefor 1 % x 33 % = 0.33 % or 3.3 per mille. I don't want to judge over that, if someone cares about this deviation weighing is probably the right thing
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https://en.wikipedia.org/wiki/Thermal_expansion#Thermal_expansion_coefficients_for_various_materials
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http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_006e/0901b8038006e13c.pdf?filepath=propyleneglycol/pdfs/noreg/117-01785.pdf
> Even if they did, you would need to ensure all the liquids are the same temperature when measuring them out.
Nothing is easier as having two liquids at room temperature.
> EDIT: Removed this graph of PG density as it was hard to read and possibly inaccurate/incorrect.
You can use the thermal volumetric coefficients, it's:
V(T2) = V(T1) + V(T1) x Coefficient x (T2-T1)
This gives for propylene glycol at 20 °C temperature difference:
100 ml x 7.3 x 10^-4 1/K x 20 K = 101.46 ml
And for glycerol:
100 ml x 4.85 x 10^-4 1/K x 20 K = 100.97 ml
Difference is 0.48 %.
But I don't recommend to open bottles at low temperatures, because it sucks air into the bottle upon opening and water from air condenses into the bottle faster this way. Objects colder or warmer than the environment generate an airflow around themselfes. This is called: https://en.wikipedia.org/wiki/Natural_convection
If you are mixing at home by weight, you don't even really need to know specific gravity at all, assume 1ml to 1gr and 99% of your recipes will come out fine. Good points for the beginners though, great work.
I know you couched it in "YMMV," but I seriously disagree with the "cheaper flavorings with volume vs weight" idea.
I can buy the same exact flavorings a volume mixer does... But beyond that, I don't see how Wizard Labs is any cheaper than the other places, unless you're buying in bulk - and that choice has absolutely nothing to do with mixing preference.
>Unless you are mixing so much juice you could start your own company, there's zero benefit to mixing by volume
Actually even if you are a large company, weight is still better, as I recently learned from the Molecule Labs video. The reason makes perfect sense too. Volume can change with temperature, weight does not, so you're mixes are consistent even at extreme temperatures.
I'm a very lazy DIYer but my method works for me. I choose a recipe that sounds good, and that allows me to purchase the flavor in the required percentage. At minimum I mix 250ml at a time. So I place a lot of trust in recipe reviews. But it works for me.
Typically I'll buy 500ml of 36mg pg base. Then 2500ml vg. That gets me 3 litre bottles of roughly 6mg (slightly less when flavoring is added).
I'll add flavoring to empty bottle first. Let's just say 6% strawberry 8% vanilla bean ice cream (mustard milk). So I buy 60ml strawberry and 80ml vanilla bean. Dump in empty container, add premixed base. Done.
Yes I know it limits my options (never do recipes with tiny percentages) but all the recipes I've used so far I've enjoyed more than juice I've bought, and I just have to dump, mix, enjoy.
I just wished I could find the American Weigh Scales LB-501 in Europe/Sweden. Could you recommend something similar?
I already have a pocket digital scale, but it's not reliable and keeps jumping around/doesn't lock in.
Now that's a tough call. If you can't find a local brand that both had a capacity of about 500g and measures down to 0.01g, I would probably try eBay or your regional Amazon.
Unless you mix big batches, you don't need the 500g one. There's plenty of 100g 0,01g scales to found in Europe. Both on Amazon.co.uk and Amazon.de, or you can do like me and order from one of those cheap Chinese sites because you don't want to spent 7eur on shipping for a 6eur scale. Sure the shipping time is long, but you do what you gotta do to save money as a student.
500g capacity isn't much more expensive than 100g, there are lots of scales for around $15 at both ratings. If you want 0.001g accuracy however..
Also be aware that customs might hit you with additional taxes if you order from outside of EU, I bought some electronics from Hong Kong and had to pay something like $80 for customs alone, quite a nasty surprise.
As long as you mix less than 100mL batches, 100g scale is okay.
I thought you were doing mixing vocabulary this week :b there is a new YouTube channel the name is escaping me but I've seen the guy on DIY or die Facebook who mixes by nothing but volume. I told him to get a scale and said he has one that wants to show people you can get into this without a huge upstart. That's all well and good but you're talking about the difference of $15 I would recommend buying your lb 501 on eBay it comes from Amazon and you don't have to pay shipping.
I had that last completely done, but forgot to transfer it to a thumb drive before I wiped my computer for a fresh install.
No worries though. I'll keep it in my back pocket, but I've been getting blown up with volume vs. weighing questions recently, so this comes first.
I see you didn't listen to Wayne when he said to back everything up a smart man learns from his own mistakes a wise man learns from other people's mistakes.
There are some open questions left for me, I'd like to ask:
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You wrote weighing is more accurate, but how can I go to smaller steps than drops? One drop is about 0.05 g, so what is the favor of having a scale with 0.01 g accuracy or even less?
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How to weigh without syringes? In the lab, when measuring liquids on a scale I'm normally using syringes anyway, they have, due to the thin cannula, a smaller drop size than normal dripping bottles, and by holding the needle to the walls of the vessel even smaller amounts can be taken. It has another favor which is, I can measure the amounts before they are in the bottle. How does it work without syringes? Is it poured directly from one bottle to the other with dripping cap? Are the base liquids dripped as well or poured?
A comment on the following:
> The discrepancy comes from the fact that the blunt tip needle holds a certain amount of liquid that can go unaccounted for. So, without proper attention to that, you could potentially ruin smaller juice batches and testers.
The volume in syringes is best read top down, this means there is no liquid in the cannula, because some air is drawn in during turning it 180 ° around and adjusting the pistol to some even number. Best method is using long needles, because they can be bended in an 180 ° angle so during drawing up the liquid or before taking it out the syringe has already the right position and nothing drops out of the needle while changing the vessel. If there is a pin at the piston, relevant for 1 ml syringes, it's good to mesasure that pin volume in order to subtract it from the final volume. This is not relevant if the syringe is not used top down, as the reason for it is to offset the dead volume where the needle is fixed before the scale begins.
There are micro pipettes with disposable pipette tips which are extremely accurate (given that the room is tempered) at scales down to 0.1 µL. Not really cheap but this is what is used in chemical and biochemical laboratories all around.
You make great points, and you obviously have more experience than me in a lab setting with these tools, and even more. So in the spirit of healthy conversion, here are my thoughts:
- The only thing I'm going to argue here is that drops weigh about 0.025g +/- 0.005g. So this does make it difficult to get it more precise than that. However, if a flavor is so concentrated that that margin of error is unacceptable, I dilute the flavor. This puts the margin of error within an acceptable range. However, I have found that margin of error to be much higher with syringes, entirely dependent on the gauge of the needles and capacity of the syringe being used. Obviously, the smaller the needle and syringe, the more accurate it is. You also brought up a great tip of measuring top down. This is something that seems so obvious I feel stupid having to have it pointed out to me. However, at the end of the day, using smaller syringes and measuring top down means even more of a time investment for extra that can be gained by using a scale.
- So yes, the idea of that we are transferring flavors directly from the flavor bottle to the mixing vessel. What happens when you over drip? You screw to the whole batch. That is definitely a negative I did not think to list on the original article.
So, my take away from your post is that it's ultimately up to each individual person to determine which method they are most comfortable with and which produces an acceptable margin of error for them, because nothing is ever going to be 100% perfect.. However, if you're going to choose to mix by volume, why not just buy a scale to verify all measurements are as accurate as possible. You are already taking the time of going through the lengthy process of pre-measuring and clean up. It's just becomes an added measure of accuracy.
> You make great points, and you obviously have more experience than me in a lab setting with these tools, and even more.
Thanks! However, this is not my everyday standard mixing technique for e-juice, but how it would be state of the art. Reality looks a bit more rude, especially if I'm in a hurry. :-)
> The only thing I'm going to argue here is that drops weigh about 0.025g +/- 0.005g. So this does make it difficult to get it more precise than that.
Checked it out yesterday and you are absolutely right, I measured 40 drops of propylene glycol and got always ~1 g on my scale. But going more into detail, drop mass depends linearly on surface tension and diameter of the tube where the drop grows, so a higher diameter opening should give bigger drops. The formula is very simple:
https://en.wikipedia.org/wiki/Drop_%28liquid%29#Pendant_drop_test
"In medicine, droppers have a standardized diameter, in such a way that 1 millilitre is equivalent to 20 drops. And, for the cases when smaller amounts are necessary, microdroppers are used, in which, 1 millilitre = 60 microdrops."
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