I did look into 1,3-propanediol for a bit, but ran out of time the day I tried to source it.was it you who only uses pg distilled from glaciers?
i think it was you who is fussy
Quite a bit more expensive but has some good qualities to it. Mostly better than regular PG.
Physical and chemical assessment of 1,3 Propanediol as a potential substitute of propylene glycol in refill liquid for electronic cigarettes | Scientific Reports