No prep, use inside or out, no sealer or varnish required. Waterbased and non-toxic. THIS IS A DISCONTINUED ITEM - left in stock: (2) #05 bright yellow, (4) #07 lt. apricot, (3) #08 peach blush, (1) #17 soft blue, (1) #18 heritage blue, (3) #27 sage green, (1) #28 sedona clay, (6) #30 expresso bean, (1) #31 colonial grey. Original price $2.39.