Pick up almost any bottle of e-liquid and you will encounter a label dense with abbreviations, ratios and terms that mean nothing to a first-time buyer. PG/VG ratios, mg/ml concentrations, salt versus freebase designations, shortfill formats — none of this is intuitive, and unlike food labelling there is no universal consumer-friendly standard that makes e-liquid labels immediately readable. This guide decodes every element you will encounter on an Irish e-liquid label, explains what each component does and why it matters, and helps you identify what combinations to look for based on your device and preferences.
PG and VG: The Foundation of Every E-Liquid
Every e-liquid is built on a base of two ingredients: Propylene Glycol (PG) and Vegetable Glycerin (VG). Both are food-grade compounds with extensive histories of safe use in pharmaceutical, cosmetic and food applications, and they perform complementary and distinct functions in an e-liquid.
Propylene Glycol (PG) is a thin, low-viscosity, water-miscible liquid that carries flavour compounds more efficiently than VG and produces a noticeable “throat hit” — the slight scratch at the back of the throat familiar to former cigarette smokers. High-PG liquids produce a more pronounced throat sensation and generate a less visible, more discreet vapour. PG is also hygroscopic, meaning it absorbs moisture from surrounding tissue, which explains the dry mouth sensation many vapers notice with regular high-PG use.
Vegetable Glycerin (VG) is a thick, viscous, mildly sweet liquid. High-VG liquids produce dense, visible vapour clouds, deliver a softer and smoother draw with minimal throat sensation, and are standard in sub-ohm and direct-to-lung devices. VG’s thickness requires devices with wider wicking ports to prevent dry hits; it flows too slowly for older narrow-wick coil systems and some pod formats.
Understanding the PG/VG Ratio
The PG/VG ratio is expressed as two numbers separated by a slash, with PG listed first: 50/50, 70/30 VG, 80/20 VG. Here is what each common ratio means in practice:
- 50/50: Balanced throat hit and cloud production. The standard ratio for pod systems, MTL devices and nic salt liquids. Compatible with almost any device. The most versatile starting point for beginners and the most forgiving choice for new device purchases.
- 30/70 or 20/80 (high VG): Dense clouds, smooth draw, minimal throat hit. Designed for sub-ohm and high-powered DTL devices. Not suitable for older narrow-wick devices or most pod systems due to liquid flow limitations.
- 70/30 or 80/20 (high PG): Prominent throat hit, thin vapour. Less common in modern products; found primarily in older formulations and some dedicated nicotine replacement focused liquids.
Device matching rule: Pod system or MTL device — use 50/50 or higher-PG liquid. Sub-ohm or high-powered device — use 70/30 VG or above. Using high-VG liquid in a narrow-wick pod causes dry hits and flooding; using 50/50 in a sub-ohm tank works but may reduce vapour density compared to a high-VG liquid.
Nicotine Concentration: mg/ml and Percentage
Nicotine strength is expressed in milligrams per millilitre (mg/ml). Some labels additionally show a percentage equivalent: 10 mg/ml equals 1.0%, and 20 mg/ml equals 2.0%. Under EU TPD regulations, the maximum permitted nicotine concentration in a consumer-format e-liquid bottle (10 ml) is 20 mg/ml. Shortfill liquids — larger bottles of 50 ml or 100 ml — must contain zero nicotine to be sold in this format; you add a separate “nic shot” (an 18 ml bottle of 18 mg/ml or 20 mg/ml freebase nicotine) to reach your preferred final concentration in the blended volume.
Freebase vs Nicotine Salts
The type of nicotine used is one of the most important and least clearly communicated label elements. Freebase nicotine is the traditional, unprotonated form — alkaline, slower absorbing through lung tissue, more throat sensation at equivalent concentrations. Nicotine salts (labelled as “nic salts”, “salt nic”, “nicotine benzoate” or “nicotine bisalicylate”) are produced by reacting freebase nicotine with an organic acid. Nic salts absorb more efficiently, reach peak blood levels faster, and allow 20 mg/ml to be vaped smoothly without the harsh throat sensation that equivalent freebase would produce.
Most disposable vapes and modern pod systems use nic salt formulations. Most shortfills and sub-ohm tank liquids use freebase. If the label does not specify the nicotine type, a 10 ml liquid at 20 mg/ml is almost certainly nic salt; a shortfill at 0 mg is freebase base liquid awaiting a nic shot.
Flavour Descriptions: What They Signal About the Liquid
“Iced” or “ice” indicates menthol or cooling agent content — usually koolada (WS-3) or WS-23 — producing a pronounced cold sensation on exhale. “Fresh” typically indicates lighter menthol treatment. Dessert descriptors (custard, cake, pastry, biscuit) indicate sweet, creamy profiles using high-VG bases that contain sucralose sweeteners which caramelise on coil surfaces and shorten coil life. Sour fruit flavours frequently use malic acid or citric acid for authenticity — both are mildly erosive to tooth enamel with repeated daily exposure. Complex “layered” flavour descriptions with more than four distinct components are usually marketing rather than a reliable guide to the actual taste experience, which is highly subjective and device-dependent.
Shortfills: The Format That Needs a Second Purchase
Shortfill liquids deserve specific attention because they require an additional step that their labelling does not always make obvious. A 50 ml shortfill in a 60 ml bottle contains zero nicotine and leaves 10 ml of empty space — into which you add one 10 ml nic shot of 18 mg/ml freebase nicotine to create a final blend of approximately 3 mg/ml. A 100 ml shortfill in a 120 ml bottle requires two nic shots to achieve the same concentration. Different shortfill sizes and different target strengths require different nic shot quantities; most reputable brands provide a mixing guide on their website or label. The practical limitation of shortfills is that they use freebase nicotine in the final mix, making them unsuitable for higher-power pod systems that work best with nic salt liquids.
TPD Compliance Markers on the Label
EU TPD-compliant liquids sold in Ireland must carry health warning text covering at least 30% of the label surface, list all ingredients including flavour compounds, show nicotine content in mg/ml and per unit dose, provide the manufacturer’s name and EU contact address, and include a batch number and best-before date. Any e-liquid missing these elements is either non-compliant with TPD requirements or has a labelling defect. In either case, it should not be purchased — the absence of required information makes product traceability impossible and removes any basis for confirming the nicotine content and safety of the product.