Menthol is actually really easy to work with.
You do not need pga or anything to make it dissolve.
Menthol dissolves at a temperature only slightly higher than room temperature.
When I prepare it I typically add a given amount directly for use rather than making 'drops'.
You can add either whole crystals or crushed (i use morter/pestle, easier to measure amounts, and dissolves faster) into the PG or VG. Shake a bit to distribute. Turn the tap faucet to hot and fill a glass with hot (not scalding) water. Drop the closed bottle in that glass and let it sit until it cools (about 15 minutes). If it isnt fully dissolved, refill the glass with hot water again and it should be fine after the second time
through.
I have never done a concentrated mix, so it may or may not take longer for that to dissolve completely. Give that a shot, should be fine.
(do not use extremely hot water, dont want to melt the plastic bottle
)
(do not microwave.... seriously.. dont)
Just water hot straight from the tap will do it great.
