Glycol – What is it in Vaping?

Definition

Glycol is the collective name for colourless, slightly sweet liquids—propylene glycol (PG) and ethylene glycol—that form the main carrier base in e-liquid. In vaping, propylene glycol is the safe, food-grade variant used to dissolve nicotine and flavour concentrates, then vaporise at low temperatures. It delivers the familiar “Hit“>throat hit” that ex-smokers crave, carries flavour accurately, and keeps viscous vegetable glycerin (VG) fluid enough to wick efficiently. Because glycol is thin and hygroscopic (water-attracting), it also prevents the gurgling noises and gunk build-up common with thicker blends, making it a staple ingredient from starter pods to high-end Genesis atomizers.

Technical Details

Propylene glycol has a molecular weight of 76.09 g/mol, boiling point 188 °C, and viscosity of 42 mPa·s at 25 °C—far lower than VG’s 1,410 mPa·s. This low thickness means 50/50 or 70 PG blends wick rapidly through small cotton channels, preventing dry hits in glass tanks or gold-platedcoil decks. PG is miscible with water, so it also lowers the overall vaporisation temperature, allowing 7–15 W mouth-to-lung devices to produce satisfying vapour without overheating. Pharmaceutical-grade USP/EP propylene glycol must exceed 99.5 % purity to avoid residual chlorides that could etch heating coils. Ethylene glycol, sometimes confused with PG, is toxic and never used in reputable e-liquids; responsible Australian vendors certify “PG-only” on labels and SDS sheets.

Usage & Tips

  • Ratio choice: Start with 50 % PG if you want noticeable throat hit and clear flavour; increase VG for denser clouds, but expect slower wicking.
  • Prevent leaks: High-PG juice can seep through worn O-rings—check seals monthly and avoid over-tightening glass tanks.
  • Avoid dehydration: PG draws moisture; drink water and rotate e-liquid strengths if you experience dry mouth.
  • Storage: Keep glycol-based liquids below 25 °C and out of sunlight; oxidation can create a peppery taste that mimics nicotine “hot spots”.
  • Coil life: PG cleans coils naturally, but sugary flavourings still create gunk; rinse coils every 2–3 days to extend lifespan.

History & Context

Propylene glycol was first aerosolised in 1942 US military smoke machines, proving its safety for inhalation. When vaping emerged in 2003, early Chinese e-liquids adopted 80 % PG formulas for portability and flavour fidelity. Australian regulations now mandate child-resistant caps and nicotine scheduling, but glycol remains the trusted carrier across disposables to rebuildables.

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