These are candle holders . There is no INSIDE to paint. I used Elmer's Glue poured into a cup and then added small amounts of Wilton's Food Coloring until I liked the color Then I used a soft paint brush . It's amazing after it dries it really dries transparent. You don't need a sealer. If you do it for a vase you still need to paint the outside because it is not water proof. Hope that helps!
Modern painted rocks - DIY on large river rocks for decoration on fireplace hearth?