Remove all sheets and covers as well as any mattress pad or cover.
Shake some baking soda on the feather top and allow it to sit for 30 minutes.
Use a hand-held vacuum or vacuum hose attachment to clean up the baking soda.
Mix detergent with warm water to make a warm, soapy solution.
Use a towel or rag to wipe the feather top clean with the soapy solution. Pay special attention to stained sections of the mattress. Wet another towel or rag with plain water and wipe down the mattress. Use a third dry towel to dry off the feather top.
Use a steam cleaner with hose attachment to gently steam-clean the feather top mattress. Allow the mattress to air dry before proceeding.
Replace any mattress covers, sheets and bedding covers.