My logic worked!

Step 1: Probably Not New to Some/most People

I was painting the fence at my place with a variety of paint (being creative)

Step 2: I Should Have Read the Paint Labels

I was dropping the used paintbrushes into my can of water for cleaning them.

Step 3: Oh, ^%@!

Of course one of the colors was not water clean up. & the container of mineral spirits had nothing in it.

Step 4: An Ah-ha Moment!

As I was searching for another solvent, I spotted the WD40
I figured if it could de-gunk stuff....

Step 5: Nice!

The paint brush was clean!!!

I may not buy mineral spirits again.
WD40 doesn't evaporate it I don't tighten the cap enough

If you wanted to after absorbing the excess off..,
You could then use some nicer smelling stuff (soap) shampoo works great for greasy hands