If yesterday’s feast left your porcelain sink stained here’s a natural, homemade solution to rid those stubborn stains: mix 2 tablespoons of cream of tartar with enough fresh lemon juice to make a paste. Rub over any spots, marks, and stains. Let this sit for about a half hour. Then rinse. The lemon juice acts as a natural bleach while the cream of tartar scrubs away stains and fills in scratches!