Liquid latex does dry out and can be damaged from the summer heat. I keep all my latex props in the house as it gets quite hot here in arizona. you can't really remove stain since it,well, stains the item it's applied to. My only suggestion would be to cut off as much of the old panty hose with a knife or scissors (carefully) as well as any built up latex,maybe prime it white and then just apply your new technique over whats left on the bucky.