How to Clean Terrain Tiles Safely?

['Scaper94]

Resurrecting this thread in hopes of finding a solution.

I have several pieces of terrain with various paint jobs from over 10 years ago that I'm trying to restore: unprimed and painted, primed and painted, and some with sealant. To my knowledge the paint is all acrylic. The unprimed pieces are washing off (mostly) fine with soapy water and an old toothbrush - I'm even using a bit of pine-sol for added measure. The primed pieces, however, are proving difficult. I haven't attempted anything yet with removing sealant.

Are there any known effective ways to go about removing the paint? My concern is going too heavy with the products I use and ruining the tiles. If it wears away some of the original paint, that's not the worst thing. But I don't want to melt or warp the tiles in any way.

For reference, my next plan of attack is rubbing alcohol and an abrasive scrubby. Acetone and paint thinner are on the to-do list as well if the rubbing alcohol is ill-advised for what I want to do.