Mix 1 tbsp of peroxide acid and 2 1/2 tbsp baking soda in a small bowl. Stir until it becomes a paste. Using a clean cotton bud, coat the surface of your nail with the paste. Let stand for 5-10 minutes. Rinse thoroughly and massage fingernails with hand cream or cuticle oil. Repeat this treatment on your yellow nails every 6-8 weeks.