Fill Cracks Before Painting Before painting, Mulco's Crack and Gap Filler fills up the cracks and small gaps between baseboard or mouldings and the walls and ceilings. FEATURES AND BENEFITS Does not affect paint gloss. Does not cause cracking of primer and flat-finish paints. No sanding required. Can be painted after 2 hours. It can be used for interior and exterior use. AVAILABLE COLORS Back to Mulco