If your bathtub is dull and worn this usually means that the glaze which is the shiny surface on the tub is worn down to the porcelain. The porcelain part of the tub is just the color but it is not a protective coating from contaminants . Even though you are able to scrub your tub abrasively to get it clean it will only stay clean for a few shower uses. Each time you try to clean your tub using more abrasive chemicals the worse you are making the surface. Your easiest solution to this problem is to have your bathtub professionally reglazed. Remember resurfacing,refinishing and reglazing are all the same. If your bathtub looks like our picture illustrated here it is time to regale tour bathtub.