i never sealed them before staining as this would not allow the stain to penetrate. try some old useless antlers first. i have used oil paints thinned with laquer thinner and start very light and build up to desired tint. also a powder called potassium permangenate from a plumbing store or well driller mixed with denatured alcohol will stain them. start out with a thin mixture and build it up. it will go on purple but will turn brown. definitely do this outside or good ventilation.