What is the best way to prepare a surface where the colour has faded?
Surfaces where the colour has faded due to exposure to ultra violet sunlight should be thoroughly cleaned down to removed all dirt, grease and surface contaminants. Then rub down with a suitable abrasive, dust off and paint over.
Weathered woodwork previously coated with a woodstain or varnish should be thoroughly prepared to remove all grey denatured timber prior to redecoration.