Do you know what you're vaping? Propylene glycol (PG) and vegetable glycerin (VG) are the main liquids in vapes. When heated, these chemicals turn toxic and aren't safe to breathe. VG vs PG Explained: E Liquid Ratios Guide Ecigone VG and PG in E Liquid: What Are They? Max VG Vape Juice: What Are the Pros and Cons? VG PG Ratio Explained: Choosing the Right Vape Juice for Your Kit VSAVI E Liquids Vape Kits What's in an e liquid or vape juice? The main ingredients are propylene glycol (PG) and vegetable glycerine (VG). These are solvents that are basically used to dissolve and carry the other ingredients.