Perlite is actually a form of porous glass that is made from a mineral called obsidian (or an aluminum silicate rock). It's heated and kind of popped like popcorn. Vermiculite is mica that is treated in much the same way. Trapped moisture expands and creates lots of air pores in both products.

In soils, perlite promotes drainage and improves porosity. It's also effective for starting seeds & cuttings. Actually, perlite holds quite a bit of water @ about 3/4 quart per gallon of perlite. The dry weight of perlite is about 7 lbs/cu ft. Wet, it weighs about 18 lbs for the same volume, so it holds more than 2-1/2 times it's weight in water. Vermiculite is about the same density, and has a even higher capacity for holding water and a very high cation exchange capacity. It also contains magnesium and potassium that are available for plant uptake, but it is not very durable and will compress if handled when wet. It also has a slightly higher pH than perlite.

Misting isn't necessarily a good thing for plants - and while vinegar with it's acid component, at toxic levels is a herbicide, it is also often used as a container soil acidifier in solutions up to 1/4 cup per gallon. It is also an effective fungicide at 3 Tbsp. per gallon of water - especially if you add a Tbsp. of sulfured molasses to the mix.

Al