Possible Clues:

• Works with oils, perhaps
• That is not in the postscript as the artist does it
• Freshens a wall, perhaps
• Coats for them are not in the postscript
• Wields a brush
• Coats go on, not in the postscript
• It is not in a postscript that one puts a coat on (6)
• Puts on a coat?
• They're put on in coats but are not inside
• Art supplies