“Discovered” an almost perfect case lube for my application*. Mineral spirits. 5 drops in a freezer bag, rub around, toss in brass. Shake. Evaporates in about 3 hours. I unfortunately now have a gallon of a product that gets used 5 drops at a time.
*9mm progressive reloading. Desired characteristics: slick enough to smooth out the progressive reloading process, and not leave behind a residue (collect dust, increase bolt thrust). 99% isopropyl was perfect**, except that it evaporates too fast.
**Yes, weirdly, alcohol is a good lubricant.
July 13 update with more experience and less optimism: I now use a small squirt in a bag and rub. It seems to last maybe 2 hours. I might end up moving to spraying the cases. I’ve been concerned about the impact of the mineral spirits on primers, but initial experimentation indicates a drop of spirits in a casing will not inactivate the primer - perhaps provided some time has lapsed (tested at 24 hours). It may be less, or there might not be any delay needed..