Get Charred Bits
First, remove racks and use a dry scrub brush to break up large charred areas and loose crumbs. Use the brush to gather the loose crumbs into a corner and sweep into a dustpan or vacuum with a hose attachment.
Make a Baking Soda Paste
Next create a paste made of baking soda, water and a squirt or two of dish soap. Mix thoroughly until you have the consistency of mashed potatoes. Depending on your oven size, you may need to mix a second batch.
Apply the Paste
Use a household sponge to cover the interior of your oven with the paste. Sides, back, floor and don't forget the oven door. Make sure all area are covered, the thicker the better, especially on problem areas. Keep in mind where oven vents are located and either cover with painter's tape prior or take special care to keep paste away from vents. Be careful when working around the oven light, it can get hot to the touch when the oven is left open for too long. Close the oven door and let sit overnight.
Draw a Bath
Don't forget your oven racks, these will sit overnight too. Grab an old towel or large rag, dish soap and 4-6 dryer sheets and head to the bathtub, or large utility sink.
Give Your Racks a Bath
Lay the old towel down to protect the tub enamel from stains or scratches. Then lay the racks down and cover with very hot water. Add about a 1/2 cup of dish soap to running water, like a bubble bath for your oven racks! Submerge the dryer sheets as well, and leave overnight.
Rinse and Dry Your Oven Racks
By morning all the grime should have loosened, and rubbing a scrub sponge or even the wet dryer sheets over the racks will remove the buildup easily. Drain the tub, and use the showerhead to give the racks a good rinse. Dry and they're ready to go back into the clean oven.
Baking Soda + Vinegar = Magic
Now that your baking soda paste has sat overnight, take a spray bottle of equal parts water and vinegar and fully saturate all surfaces of the oven. You'll see the chemical reaction between the baking soda and vinegar begin to bubble and break up baked on char. Spray extra vinegar over problem areas and let the spray soak in for about 15 minutes.
Wipe Out the Wet Paste
Next take a damp sponge and wipe out all the wet paste. You will likely need a few passes with a clean sponge to get all the residue, but you might be surprised by how much brown gunk was living in your oven. For especially tough spots on the oven, a scrub brush and steel wool can help to break them up. Just be careful not to scratch the oven's finish.
Do a Final Pass
Lastly, take a final pass with a clean, wet sponge to pick up any remaining residue and your oven should be sparkling! You can let air dry with the door open, or close and heat the oven to 200 for about 15 minutes to air out any vinegar smell.
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