IDK if this is common knowledge but I've found that using low amounts of menthol in mixes will give them a nice throat hit without really tasting of menthol.
For eg here is a sort of tropical cola recipe I'm developing:
3-4% TFA Cola 1.5% TFA Champagne 1.67% menthol 1% TFA Papaya 0.5% TFA Dragon Fruit
The menthol is a saturated solution of crystals in PG at room temperature; I filled a 10ml bottle halfway with crushed menthol crystals, filled it up with PG. After a couple weeks at room temp, I have a layer of undissolved crystals at the bottom. I have been using this pretty much since starting DIY in all of my frequently used recipes, often at higher levels, so people who are less used to menthol may wish to adjust downwards. Maybe using 0.5% of saturated menthol solution instead of 1.67% would be better if you're just starting out or giving it a tty yet not fond of the taste of menthol.
Why not use koolada if you want to avoid the menthol flavor? or WS23?
I get the idea you're going for, I used to keep a "never ending" beaker of saturated 4M KCl for my research; excess crystals, add DI water, no more crystals, add more KCl. Never had to measure anything, just check the room temp.
In my experience Koolada does the opposite of Menthol when used low.
Menthol gives an extra kick whenever you use it, koolada really low has the effect of smoothing stuff out. At least i like to use it like that on fruity stuff that ends up too sweet.
YMMV.
I love koolada so much I want to add it to my food.
A solvent can only carry a specific amount of a solute at a given temperature and pressure. Once this maximum value is reached, the solution is said to be "saturated". It changes with temp and pressure. If I put my saturated solution in the freezer, more crystals would precipitate out. If I put it in a hot water bath, the undissolved menthol might dissolve, but then it would likely crash out again as it returned to room temp. If the air pressure changed, I believe similar effects would occur but that's not really relevant. Hope that clarifies things!
Why are your crystals still crystals and not dissolving?
Some dissolved but there were too many for that amount of PG to dissolve them all. I made a reply that explained it in physical chemistry terms but that somehow ended up replying to my OP and not your comment. Then I realised that maybe I hadn't spoken clearly enough hence this reply!
After testing several mixes with different percentages, I've found that what works better for me is to mix 20% crystals 80% PG using a scale. For 100 ml of menthol solvent then, it's 20g crystals and the rest is PG. It works great and it never crystallizes again at room temperature after left for about 6 hours for the crystals to fully dissolve.
This menthol lasts for a really long time in the mix, it's very strong so low percentages are needed, and it works wonders for palate cleansing purposes. Just a mix with 5% of this and it'll clean your nostrils right up.