Wash the stair treads with a rag and warm, soapy water to remove dirt, debris and body oil. Wipe them dry with a clean, lint-free rag.
Place painter’s tape along the edge of each stair tread to create a rectangle and protect the small amount of tread you will not paint with the coating. Prepare the stair treads according to the nonslip paint manufacturer's directions. This may involve the use of sandpaper or an etching product. Open windows and use fans to circulate air for proper ventilation when painting.
Mix the nonslip paint according to manufacturer's directions.
Use a paintbrush to apply a thin coat of the paint in a vertical direction to the exposed stair tread. Let the first coat dry and apply a second coat if desired.
Allow the paint to dry according to manufacturer's directions before removing the painter’s tape. Keep pets and people off the stairs during drying time to prevent damage to the finish.