UNi-PRO You Can Do It 230mm acrylic roller covers have a 10mm nap making them ideal for walls and ceilings, flat or low sheen finishes. Uni Pro acrylic rollers are thermally bound to the core for extra solvent resistance, and superior paint pick up. Handy Tips: If you are painting overnight, make sure you wrap up your paint roller covers in cling wrap, so they don’t dry out. They can then be reused the next day to finish off your painting task. When painting a room always start on the ceiling and then work your way down from there. Ceiling, walls, trims and finally doors.