How can I remove stains from my tub.. its all yellow. I recently moved into a new house. The bathtub is extremely stained. I tried using bleach scoring powder and spirit of salt... I just ended up with a soiled tub with the paint coming off the base... I am not sure what material the tub is made of but judging from the dark material revealed under the paint am guessing iron. I have considered painting with car paint a gloss but tought against it because it might just come off