Hi Mike!
I know this thread is about compounds and polishes, but the confusion applies to other stuff, too.
I also catch myself loosely using the terms
water based or
solvent based quite a bit.
Since water is a solvent...

(well, it is!), even these terms are not technically accurate or specific.
Oftentimes, I am referring to the
carrying agent as being a water or petroleum solution.
So, if I am telling someone to, "...Wait for the tire dressing to
soak in before wiping the excess", I then mention that, "...the dressing is not soaking in all that much. Instead, the
carrying agent is evaporating, which gives the illusion that the tire dressing is
soaking in." If the dressing uses water or a water-blended liquid to carry the protecting agent(s) onto the tire, it is best to let the carrying agent evaporate. Otherwise, most of the protecting agent will be wiped away as easily as it was applied.
Other examples of carrying agents?
Kool Aid!
A bit of a stretch, but a packet of flavor particles are added to a pitcher of water, and the water "carries" or "suspends" the flavor particles. Whether the flavor particles completely dissolve or not (officially termed
instilled- the opposite of
distilled) is debatable (I do not wish to debate this point)

rops:.
Aerosol spray paint!
Generally, a petroleum solvent is used to suspend or carry resins and other ingredients onto a surface. Some ingredients are added to allow the paint to smooth out prior to drying. Others are used as a propellant to aid in lifting the paint out of the can and through the nozzle. As the solvents evaporate, the remaining ingredients attach to the surface.
Those are two examples, but there are many others.
Products that move or push material out of the aerosol can via pressure are referred to as
propellants or
propelling agents, and most times are petroleum solvents (they can double as carrying agents, too!). Propellants tend to evaporate very quickly (acetone, butane, methyl ether, etc.) and are often damaging to delicate surfaces. This is why a guy should not blast his air vents to the point of saturation when using an aerosol interior dressing.
Okay, so I think I've written a bit too much on the subject... Hey, I was on a pizza break. :righton: