1 Sprinkle the carpet generously with baking soda, and brush in. 2  Allow to set for a few hours, overnight if possible. 3  Then vacuum thoroughly and get ready to give the carpet a good shampooing with a steam cleaner. 4  You will not be able to vacuum out all of the baking soda and that's okay. Sprinkle the carpet generously with baking soda, and brush in. 2  Allow to set for a few hours, overnight if possible. 3  Then vacuum thoroughly and get ready to give the carpet a good shampooing with a steam cleaner. 4  You will not be able to vacuum out all of the baking soda and that's okay.