I actually prefer MIBK far over MEK for thinning, but it is far harder to find.
West Marine used to carry it, but no more.
There is one industrial paint supply near me that does but they now charge $40/gal.
That styrofoam dissolved in MEK sounds a lot like the plastics in commercial sanding Sealer.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, TURMOIL, FIASCOS, and HAVOC !