[header] How to touch up paint [title] Wash the walls. [substeps] Soak your sponge in soapy water and wring out excess moisture. Wash your walls with the sponge to remove surface dirt, marks or grime. 
Dry the walls with a clean towel, and rub a soft cloth over the painted surface if it looks dull. Dullness occurs on some glossy, paint surfaces after repeated washing.