Could nail polish damage pure PLA?
This is an ugly question, and an ugly answer.


Nail polish doesn't come with an ingredient list. Nor are there MSDS's available to refer to what solvents are in it. So it's "unknown 1"
Most every filament company will not give you a list of compounds for colorants or plasticizers used. MSDS is off the table. So, even though we do know what PLA and ABS is inherently, we have no clue about the other ingredients used to make your particular filament. This is "unknown 2".


What both of these comes down to is a very nasty situation indeed. We know for a fact that ABS dissolves into acetone. PLA does not.... Except we have had reports of PLA that does. When we look further into those responses, and ask them to do a burn test, they smell popcorn and something acrid (ABS). 

This guarantees unless we have virgin material and MSDS in hand, you only have a close guess at what material you have. And that's to say nothing about "nail polish", and its components.

There are also other solvents that will dissolve PLA. MakerBot back before they turned evil, noted a solution called Beta Solution (90% isopropyl alcohol, 9% KOH, 1% Al(OH)3  ). This stuff is noted for dissolving PLA and leaving ABS intact.

Long story short: "Could Nail Polish damage pure PLA?" We can't guarantee purity of PLA, we can't guarantee contents of nail polish's solvents. The only answer is to print a swatch and test yourself. Calibration cubes are quick and easy.