I ran out of propylene glycol (pg) for DIY eLiquid (for electronic cigarettes) and did some searching on the internet. It turns out that a company named Tractor Supply sells proplyene glycol, USP, for around $20 a gallon. Great deal. Better yet, there is a Tractor Supply down in Gilroy, about 30 minutes south of San Jose, and I drove down and snagged a gallon, which will last me a long time; for example, if I use 20% flavorings,100mg/mL nicotine solution, and I desire 25mg/mL of nicotine in my eLiquid, I'll need 2.75mL of PG for every 5mL of eLiquid I make. A gallon contains 3785.41mL, so a gallon will net me ~1377 rounds of 5mL eLiquid. Awesome.
I have made a couple of 5mL batches and must say that I have not noticed a difference in taste of my eLiquid.
Creation Date: 2016-05-26
Propylene glycol is useful as a solvent for flavorings and food colors. PG has low density which means you will get less gunk when compared to VG.