e-Liquid consists of three basic parts: nicotine, liquid and food-grade flavoring. Nicotine is extracted from tobacco plants in a pharmaceutical lab and diluted to workable levels with propylene glycol (PG) or vegetable glycerine (VG). The solution is then combined by the factory or individual making the final product with more PG or VG and the flavorings.
Nicotine content in e-liquid is generally measured in milligrams per milliliter. Common nicotine levels in commercial generally ranges from 0 – 24 mg/ml with a few vendors selling slightly higher concentrations. Concentrations may also be expressed in percentages. An e-liquid with 18mg may be referred to as having 1.8% nicotine.
Choosing the right level of nicotine can be tricky as it will depend on each individual and how dependent they are on nicotine. It’s fairly common for people to start high using 24 or 18mg and then working down to a more comfortable level. If you’re just starting out it may be a good idea to get some liquid or pre-filled cartridges in a higher and lower level until you can determine what works for you.
e-Juice made from PG tends to be a thin and runny liquid. PG liquids are know to produce an OK amount of vapor but provide an excellent throat hit. Throat hit is the sensation you get in your upper chest and throat when inhaling, similar to the experience of smoking an actual cigarette. Some also feel flavors are transferred better in PG liquids.
VG is a very thick solution and is often thinned out with pure grain alcohol (PGA) or distilled water to make it easier to work with and perform in e-cigarette hardware like cartomizers. Glycerine’s biggest advantage is a significantly higher volume of vapor than PG based liquids. VG, however, notably lacks in the throat hit department.