Nail Polish remover=BAD. DO NOT USE IT. Acetone in and of itself is a solvent that wouldn't harm your cpu die or packaging, however, nail polish remover is not straight acetone. It often contains not only fragrances and dyes, but many varieties contain a form of dissolved GELATIN. Meaning when the Nail Polish remover evaporates, you're left with that crud on your processor dye and/or HSF. The best and safest thing to use is Isopropyl alcohol. The stronger the better. It doesn't have to be 100% but make sure it isn't mixed with anything besides water on the ingredients label.
Honestly.. I don't know why people make this so hard.. and/or refuse to take notice of the easiest method to clean AS off a core.
Just use an eraser (clean) from a pencil. Its very simple. Just scrub the core with the eraser and blow off the resulting eraser stuffs. No chemicals needed. Only issue I've had is accidentally erasing my L1 bridge mod and having to do it again... whoopee.