hey lifeburn, im not sure id use any type of spray can for a sealer on latex, it will crack in my experience ive learned,
if u really want a sealer use permawet or they sell also a medium gloss sealer in a jar from micheals that
i know some artist use also, if u want to use permawet just add some dust or translucent powder to dull it down.
really hope ur armor comes out good !
ernie