I want to begin with some background and how this post came to be. Unfortunately I am at a loss in how to communicate in few words. I can whip out 100 page essays with no problem but when it comes to this form of writing I simply don’t know how; plus there is a lot of ground to cover.
Nothing stated should be interpreted as implying that the use of this very expensive equipment is necessary to make good e-juice. It simply isn’t. I believe it far more important to understand the science associated rather than owning the equipment. However, the usage is a “game changer” and if you are making and selling e-juice, cannabis products, oils, soaps etc., or interested in making extracts then you may want to consider owning some of this equipment. The advantages are numerous and very real.
Recently I participated in another thread which dealt with the question of whether mixers should “steep” their liquids with nicotine or add it at later time. Several thoughts and questions were posed which led to the subjects of oxidation, discoloration, and nicotine taste. These topics led me to describe my usages of lab equipment including flasks with stoppers, magnetic and overhead stirrers, a laboratory homogenizer, and my reasons/methods for using these devices. The intent is to minimize the introduction of oxygen e.g. oxidation in the mix throughout the entire mixing process concerning both flavorings as well as nicotine. To summarize:
I personally do not want to taste oxidized nicotine which can be caused by certain mixing techniques. I add it after mixing and before vaping and not before. However, I acknowledged the fact that this may not be ‘right’ for everyone. Some may very well be accustomed to the taste of slightly oxidized nic interacting with their flavorings. Whatever keeps you off the stinkies is ‘right.’
Also discussed was my position that flavorings can be severely degraded by the introduction of air into the flavoring mix which in turn will oxidize nicotine. I think it was Bo Darc on ELR that called this a no brainer; if the flavors are going up into the room air they are simply gone. Also discussed in this context was the practice of “breathing” mixes.
Also discussed were the roles of PG and VG and I referenced a video made by PBusardo during his tour of the Flavourart facility in which the owner and founder describes PG as a much better solvent/flavor carrier and why Flavourart does not make VG concentrates. To paraphrase him, the flavorings will constantly separate in VG and it is not a suitable solvent for concentrates. Personally, I use PG based nic for this reason. My opinion is that it will mix much easier and I do not want any separation or ‘hot spots’ however unlikely that may be. (I add nic with a stirrer at a very slow rpm) Also discussed were “shake the shit out of it” methods and the use of heat for mixing flavorings. I think it a very bad idea to shake nic liquids when any air is in the nic bottle. Heat will also oxidize nic so I avoid it and add it at room temp after using heat to mix recipes. I think we all know to avoid UV light with everything.
I also covered the need to use heat to homogenize VG in juice making and posted a link:
Grubby kindly suggested that those posts be moved, if I like, to start a thread on mixing techniques and the use of stirrers and lab homogenizers. Given the choice I feel like the threads were a good discussion and should be read in the context of how they flowed from and relate to the OP’s (Tinman’s) original post. I also think I covered the use of hotplate stirrers in these posts and see no real need to repeat it but will be glad to expand upon it and answer any questions. I own several types of stirring devices.
But I did venture pretty far off the path and it occurs to me that many may not know what a lab homogenizer even is or how it works. I didn’t, and had to go down a pretty deep rabbit hole to research these things. Clearly, the methods and equipment used by food and flavor processing companies is not something they will freely discuss. However, the usage of homogenizing devices is universal across all processing industries including foods, beverages, flavorings, cosmetics, lubrications, and pharmaceuticals etc. and has been dating back to at least 1948. The makers of these devices are now targeting e-juice and cannabis product businesses and I gare-un-tee-u that the products we are using are made using this type of equipment be it high shear mixers or ultrasonic sonicators. Both are “homogenizers.”
What is homogenization?
The word homogenize means “to make or render homogeneous” while homogeneous means “having the same composition, structure or character throughout”. Homogenizing is an umbrella word - a word which covers a very large area. When someone says that they are homogenizing, they may mean that they are actually doing one or more of the following; blending, mixing, (cell) disrupting, emulsifying, dispersing, stirring etc.
I think the best description is one we are all familiar with; homogenized milk. Without the homogenizing process, milk will quickly separate. By mechanical force the milk components are forced into “the same composition” and “structure” meaning a uniform particle size among other things.
I’ve been around the forums for a while now and see the term homogenize used quite a bit. But is this what is occurring with the “standard” mixing methods? Or is it a misuse of the term? We are dealing with very different substances. VG is thick, heavy, and is therefore composed of large molecules where PG is water thin. After a lot of study and experimentation it is my belief that many are innocently misusing the term. Without mechanical force further defined as “shear” we are not producing a homogeneous mixture. While it is certainly true that a certain amount of interaction and infusion does occur, it is constantly changing. Thus, the sometimes months long “steeping” process. (I think we all know that we are not “steeping” anything) IMO aging and maturation are far better terms and would eliminate much confusion especially for the beginning DIYer. True maturation occurs when the mix becomes uniform and relatively stable. Mechanical force accelerates the process whether it is with a stirring device or homogenizer. Months turn into days or minutes.
Rotor Stator Homogenizers
I began with a “cheap” used homogenizer made by Scilogex. Typical Asian knockoff junk. Two weeks later I needed a $400.00 part and instead of that bought a high quality rotor stator homogenizer made by Pro Scientific. (Pro250- Pics below) It is of very high quality and covered by a 2 year warranty and important to me-American made. That’s pronounced “muricun” for friends across the pond.
Pro Scientific’s website has a section titled “Why use a homogenizer to blend VG for e-liquid?
“With mechanical homogenizers there is 1000 times more energy than traditional stirring methods.” With Mechanical Homogenizers a higher quality and better performing finished product is produced, because mechanical homogenization allows for:
- Reduced particle size
- Increased particle uniformity
Rotor-stator homogenizers - How does it work?
The rotor-stator homogenizer or generator type homogenizer was first developed to make dispersions and emulsions, and most biological tissues are quickly and thoroughly homogenized with this apparatus. The appropriately sized cellular material is drawn up into the apparatus by a rapidly rotating rotor (blade) positioned within a static head or tube (stator) containing slots or holes. There the material is centrifugally thrown outward in a pump like fashion to exit through the slots or holes. Because the rotor (blade) turns at a very high rpm, the tissue is rapidly reduced in size by a combination of extreme turbulence, cavitation and scissor-like mechanical shearing occurring within the narrow gap between the rotor and the stator.
The first thing I noticed was a dramatic increase in flavor and I have had to reduce my flavor percentages. Nuff said.
Researching the use of rotor stator homogenizers for making e-liquids reveals claims by both users and manufacturers of these devices that the “steep” or maturation time is reduced by 60 to 80%.
From Pro Scientific: “we have been told that 15 seconds of homogenization is like a week or two of steeping.”
The 60/80% is based upon the need for off gassing and evaporation due to chemical reactions caused by slamming these molecules together at very high rpms. “Steeping” or maturation/ageing is not just particle reduction and homogenization. Evaporation is the other half of the equation.
I have now used a rotor stator device for six weeks and have yet to find a recipe that is not near instantly vapable. However, I researched the use of ultrasonic devices and found an added claimed benefit of off gassing and indeed, found references to the use of sonicators/cell disruptors used in wine making. The similarities between the wine making and e-juice making processes are shocking.
This article references many peer reviewed studies and I think very interesting for the serious e liquid maker. Bottom line: A year turns into days. Bouquet and mouthfeel, oaking etc. are accomplished.
So what I have done is after using the rotor stator is place my bottles in an ultrasonic cleaner for two minutes for off gassing purposes. I believe this solves the other part of the equation. I would have a hell of time proving this without being able to set down in a room and have people taste test. But I am producing what is so close to aged and mature e liquids that I have been unable to detect much, if any at all, difference from day one juice.
The advantages are too numerous to detail. I am not much as a recipe creator. I’m a tweaker. The ability to adjust my mixes near instantly makes this worth every penny to me. The time factor involved was the bane of my existence concerning making e-liquids. No more.
Sorry for the length.