The secret of invisible smoke from e-cigarettes

Smokeless e-cigarettes, also known as invisible smoke e-cigarettes, refer to e-cigarettes whose smoke is not visible to the naked eye. Their main purpose is to reduce the disturbance of e-cigarettes to the environment and eliminate visible "second-hand smoke."

So, how do smokeless e-cigarettes come about? The answer is the ratio of e-liquid, such as significantly reducing the amount of glycerol (i.e. propylene glycol).

E-liquid is mainly composed of five ingredients: food-grade propylene glycol (PG), food-grade vegetable glycerin (VG), food-grade flavoring, nicotine, and additives.

Generally speaking, the source of smoke is vegetable glycerin (VG), the satisfaction and throat hit come from nicotine, and the flavor and taste improvement come from spices and additives, etc. PG mainly functions as a carrier for flavorings, enhancing the taste of e-liquid. After heating, it generates a small amount of vapor. It also dilutes VG to reduce the viscosity of e-liquid and facilitate wicking. 

Glycerol (glycerin) is a high-boiling-point and high-viscosity organic compound. The vapor molecules formed after vaporization are relatively large and heavy. After being exhaled from an electronic cigarette, the process of these vapor molecules cooling and condensing in the air is relatively slow. Due to its larger molecular structure and higher boiling point, glycerol vapor can remain in a gaseous state for a longer time in the air and can diffuse more widely. This makes the produced smoke appear denser and with a greater volume.

The formulation of smokeless liquid typically involves a substantial reduction or complete elimination of glycerin. A more common approach is to utilize polyethylene glycol, an effective solvent that can efficiently dissolve various components of the liquid while also facilitating the production of smaller, more uniform atomized particles.

It is understood that to achieve a "smokeless" effect throughout the process, the amount of propylene glycol will be minimal, almost negligible, while the proportion of polyethylene glycol can reach up to 78%. To achieve light smoking with visible smoke and deep inhalation with invisible smoke, a certain amount of propylene glycol will be added. This ensures that during large circulation lung inhalation, the smoke becomes invisible; whereas during small circulation lung inhalation, the smoke remains visible.