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Tutorial - DIY Mixing Two-Part

We are all trying to lower costs and achieve a more consistent mix with our eLiquids. I have been in conversation recently where the subject turned to mixing eLiquids as a two-part system. One of those conversations was with a vendor who was planning to revamp their entire mixing lab. The plan was to separate the flavor mixing from the "base" mixing. 

Let's explore what is meant by a two-part system. 

There are only three main categories of ingredients in eLiquid. That is:

  1. Nicotine. Liquid nicotine is not available in its pure form. Pure means 1000 mg/ml and would include no base diluent. For DIY purposes, you can get liquid nicotine in strengths of 36 mg/ml to 100 mg/ml, with the most common being 48 mg/ml. At these lower strengths, liquid nicotine is usually in a diluent of either propylene glycol or vegetable glycerine (or a mix of the two).
  2. Diluent. Propylene glycol (PG) and vegetable glycerine (VG) are the two diluents. These can be further diluted, particularly vegetable glycerine to make it flow better.
  3. Flavor. Flavorings are also in a diluent, most commonly PG.

The largest quantity of these in a recipe is the diluent.

We usually mix in a "one-part" system, that is we take all the ingredients and mix them in a single container with the plan to use the mix as soon as possible. This works, but is more prone to mixing variances, is time consuming on an individual mix basis, and more labor intensive. For a manufacturer, this is also extremely expensive. We have a tutorial on DIY mixing at this page.

A "two-part" strategy for mixing is where you are essentially creating a higher concentration of unflavored vapor liquid – you can vape this or use it in a blend of flavorings. Here's an exampe. If I have a 30 ml unflavored vapor liquid at 20 mg/ml and I pour that into a 50 ml container and add 20 ml of flavoring and diluent, I end up with a nicotine strength of 12 mg/ml and a finished vapor liquid that I can use right away. The 30 ml unflavored vapor liquid is part 1 of the two-part mixing strategy. The second part, the flavoring and diluent, can either be stored in bulk or can be separated into 20 ml containers. Then you have a choice: take a 50 ml bottle and pour in your 30 ml unflavored nicotine base and then top with your second part (flavorings mix).

Mixing in a "two-part" system involves mixing the liquid nicotine with some of the diluent in larger quantities as the first part, and mixing the flavorings with some of the diluent as the second part. For a large batch, if you mix 300 ml of the first part, you have enough for ten 30 ml bottles of unflavored eLiquid.

So, let's take this one step further into a real world example. Here's the specs of the mix (for the purpose of this example, the flavoring will be a one-flavor mix): 

  • Target size: 50 ml
  • Target strength: 12 mg/ml
  • 50/50 (50% PG, 50% VG)
  • Flavor: Spearmint, which calls for 12% of the total mix to be flavoring (Spearmint)
  • Base nicotine is 48 mg/ml (PG)

To mix this as a one-part recipe, we would need 7.5 ml of PG based Nicotine, 3.9 ml of PG diluant, 15 ml of VG diluant, and 3.6 ml of Spearmint flavoring. Mix all of these in a 30 ml container and we're ready to vape. Each time I need a refill, I have to mix from scratch.

Now, let's look at this as a longer term strategy – a two-part system.

We are going to mix for a total of 500 ml of finished vapor liquid. That will give us 300 ml of "base", enough for ten 50 ml finished bottles. We are going to use a mason jar for the first part of the mix. We will need: 125 ml of PG based nicotine (48 mg/ml), and 175 ml of VG diluent. This yields a total of 300 ml of our first part – and keep in mind that this is intended for a total of 500 ml finished vapor liquid, so the nicotine strength is concentrated without the flavorings (it's 20 mg/ml before adding the flavorings).

Now we will mix the "second part" in a separate container. For our example (Spearmint), we will need 65 ml of PG diluent, 75 ml of VG diluent, and 60 ml of spearmint concentrated flavoring. This yields a total of 200 ml of our second part.

When we need a finished product, use an empty 50 ml container and pour in one of the 30 ml containers of the first part and then top off the bottle with the second part flavoring mix. Pretty simple.

This reduces cost and greatly reduces the amount of time you need to mix a batch up to vape with.

Some questions that have come up in the testing of the DIY Calculator & Recipes

  1. Why a two-part system? Mixing in larger batches helps to assure consistency and accuracy. If you make a 1 drop error in a 500 ml mix, the effects are much less dramatic than a 1 drop error in a 30 ml mix. Using the example above, mixing in a 500 ml batch all at once means that you can easily pour out ten 50 ml containers and use those rather than mix ten 50 ml batches individually. Save time, be more accurate and consistent.
  2. Why a 60/40 batch, why not 80/20? The batch sizes for first part / second part mixing is entirely up to you. I picked 60 /40 because the most important part of mixing is the first part, the "base". I wanted to get that into simple size bottles and 30 ml is the most common size that offers a variety of pouring tips. At 60/40 batches, your flavorings are also in more diluent meaning that they are steeping in the diluent while stored.
  3. With your 60/40 two-part system, do I have to use 30 ml bottles for the base? If this is for personal use, you can do anything you want. You can put 30 ml of the first part in a 50 ml bottle and cut out one step. If you are planning on selling this commercially, you have to put 30 ml of liquid into a 30 ml container. Check with your consumer goods packaging laws.
  4. Can this be used commercially? Certainly. With the growing threats of legislation banning flavored vapor liquids, it will be common to find unflavored vapor liquids in 30 ml sizes. You could make your own flavorings and add it to commercial unflavored vapor liquid. All you have to keep in mind is that the strength will be diluted when you take the 30 ml container and pour it into a 50 ml container when you add the flavorings. You need to adjust the strength that you buy from the vape store. It's pretty simple to figure it out. If you are vaping at 12 mg/ml now, and you want to buy 30 ml unflavored to mix yourself (in a 50 ml container with your own flavorings), the base becomes 60% of the total finished product. So, divide the strength by 60% and you get 20 mg/ml (12 / .6 = 20) – so you would need to buy 30 ml of unflavored vapor liquid at 20 mg/ml. I know that is a non-standard strength, so work it the other way. If you buy 30 ml of unflavored vapor liquid that is 18 mg/ml and you use the two-part strategy, you will end up with a 50 ml container with 10.8 mg/ml (18 X .6 = 10.8).
  5. Why does your illustration of the brown bottle shows 60% at the bottom and 40% at the top? I hate measuring things and having to pull out beakers or measuring cups. If you put the 30 ml first part into the 50 ml bottle first, the rest (40%) is just eye-balling.