It breaks down
I tried the nail polish- don't remember the brand. i think it was L'oreal or whatever my wife had on the bathroom counter.
Over time, stored inside the house. it seems to break down: goes from hard and clear to powdery-white, soft, and easily wiped off with fingers. it sealant properties are no doubt gone by then.
The 'real' primer sealant doesn't seem to break down- not as of yet anyway.
"Necessity is the plea for every infringement of human freedom. It is the argument of tyrants;
it is the creed of slaves." -- William Pitt (1783)