E-liquids, also known as vape juice or e-juice, are the specialized fluids used in electronic vaping devices to generate the inhalable aerosol. The primary purpose of this fluid is to act as a delivery system, carrying flavor and, often, nicotine to the user. When heated by the device’s coil, the liquid turns into a vapor, allowing for the sensation intended to mimic traditional smoking. This substance contains a small number of core ingredients blended in precise ratios to dictate the final experience.
Defining the Core Components
E-liquids are composed of four main categories of ingredients that determine their physical properties and user experience. The foundation of nearly all e-liquids is a base solution made up of Propylene Glycol (PG) and Vegetable Glycerin (VG). These two substances often account for up to 90% of the total volume and serve as the carrier for the other components.
PG is a synthetic organic compound, while VG is a natural compound derived from vegetable oils. The liquid also contains concentrated, food-grade flavorings that create the desired taste profile. Finally, nicotine is included in varying concentrations, although its presence is optional, as many e-liquids are sold nicotine-free.
The Role of Nicotine and Chemical Forms
Nicotine is a variable component in e-liquids, with concentrations measured in milligrams per milliliter (mg/mL). Users select from a wide range of strengths, often starting from 3 mg/mL up to 18 mg/mL or higher. The choice of concentration is directly related to the user’s previous nicotine dependence and their preferred delivery system.
The nicotine exists in two primary chemical forms: freebase nicotine and nicotine salts. Freebase nicotine is the traditional form, which is more alkaline (pH around 9). This high alkalinity causes a harsh “throat hit” at higher concentrations, limiting freebase e-liquids to lower strengths for comfortable use.
Nicotine salts, or “nic salts,” address this issue by adding an organic acid, such as benzoic acid, to the nicotine base. This addition lowers the pH of the solution, resulting in a significantly smoother inhalation, even at very high concentrations. Nicotine salt e-liquids are commonly found in strengths ranging from 20 mg/mL up to 50 mg/mL, enabling a more rapid and intense nicotine delivery often preferred by those transitioning from traditional smoking.
The Functional Differences Between PG and VG
Propylene Glycol (PG) and Vegetable Glycerin (VG) are the two base carriers that fundamentally shape the vaping experience. Their ratio is a primary consideration for device compatibility and user preference. PG is a thin, low-viscosity liquid that excels as a flavor carrier because it does not impart any noticeable taste. It is also responsible for delivering a sharp sensation known as “throat hit,” which simulates the feel of inhaling cigarette smoke.
VG, in contrast, is a much thicker, more viscous substance that is mildly sweet. Its primary function is to produce large, dense clouds of visible vapor. Its thickness can sometimes slightly mute the flavor intensity compared to PG-heavy liquids, and its high viscosity means it requires more powerful devices with efficient wicking systems.
E-liquids are formulated in various PG/VG ratios to balance these characteristics, such as 50% PG and 50% VG for a balanced experience. High-PG liquids (e.g., 60/40 or 70/30 PG/VG mix) are better suited for lower-power devices and users prioritizing a strong throat hit and flavor. Conversely, high-VG liquids (e.g., 70/30 or 80/20 VG/PG blend) are often used in high-wattage, sub-ohm devices by users who prefer maximum vapor production and a smoother draw.
Flavoring Compounds and Consistency Factors
The flavor component of e-liquids is created using concentrated food-grade flavorings, typically making up 3% to 15% of the total liquid volume. These concentrates are dissolved primarily in the Propylene Glycol portion of the base, allowing for a wide array of profiles, including fruit, dessert, beverage, and tobacco notes. The complexity of the final flavor profile depends on the blend of multiple individual flavor chemicals, such as ethyl maltol or vanillin, combined to achieve a specific taste.
Beyond taste, flavorings can subtly impact the liquid’s overall consistency and stability. Some flavor molecules can introduce chemical reactivity or affect the viscosity of the liquid, though the PG/VG ratio remains the dominant factor. For optimal sensory experience, the finished e-liquid often undergoes a maturation period known as “steeping,” allowing the flavor compounds to fully blend and stabilize before use.