My finishing projects have always used either oil based wipe on varnishes (several acoustic instruments) or poly (which I used on a solid body electric). I am considering my first build using nitro lacquer and I have been studying its application first. I discovered that all the major brands of nitro lacquer recommend using something called a "vinyl sealer" first to achieve an even, level surface. Well, I have hearing for years that "plastic" finishes like poly are "tone killers" and that nitro is so much better for tone because it allows the wood to "breathe", while the plastic "seals" the wood, in a bad way. Question: Isn't vinyl plastic? What gives nitro superiority over "plastic" when you have to spray a coating of plastic over your instrument anyway before you spray the nitro?