Turn off the oven if it is currently on. Allow the oven to cool before starting to clean off the carbon.
Open the oven door. Remove the oven racks.
Scrape out as much of the carbon and other debris inside the oven as you can with the nylon brush.
Mix the bicarbonate and water together until it takes on the consistency of a thick paste in a container.
Apply the paste to the carbon deposits in the oven with your hands. Allow the mixture to sit on the baked on carbon for at least half an hour.
Scrape off the carbon underneath the paste with a wallpaper scraper or mud knife. Rinse off your tool when carbon begins to cling to the end and impede your scraping.
Rinse off any residue with fresh water from the sink and a sponge, if desired.