As anyone who has cleaned a bathroom in his or her life will testify that if there is a bathtub in the bathroom, it will stain. Those people will further testify that removing stains from bathtubs is one heck of a job. But with some care, you can make sure your bathtub doesn't stain that badly at all. And if it does, here's what you can do.
Most bathtub stains are caused when mineral deposits from hard water accumulate over a long period of time, causing what we all know as rust stains. Then there are the blue stains, which are a result of mineral deposits and mildew. Both kinds of stains require a lot of hard work if you have left them to set into the surface of your tub. The golden rule is to clean your bathroom at least once a week so that stains don't have time to set and you don't spend hours removing them.
A lot of households use borax to remove hard water stains from bathtubs. It is certainly the easiest way to remove stains, because all you have to do is sprinkle some borax on the affected area, wait for a few minutes, and wipe with a damp cloth or sponge.
Alternatively, for particularly stubborn stains, you could try one of many rust-removing agents available on the market. Most of these agents contain oxalic acid, which is highly toxic, and trisodium phosphate, so you need to follow instructions carefully before using. Gloves are essential, for instance. Once you apply the rust-removing agent, you need to scour the area with a coarse brush or pumice scouring pad.
There are even stronger varieties of rust removers on the market that are ideal for removing heavy stains from bathtubs. With these removers, you can pour the remover onto the stain, let it work on the stain for about thirty minutes, and simply wash it off. If washing the stain and remover off doesn't work, scrub the area with a coarse brush before washing the stain away.
An extremely effective method of removing stains from bathtubs is to dissolve oxalic acid crystals in hot water and make a paste using some whiting, but this is only worth the effort for really severe stains. Apply the paste to the stain and let it dry, after which you must scrape it off and rinse. However, never touch oxalic acid with your bare hands or allow it to get near your eyes or mouth. Always wear gloves when cleaning your bathroom.
Blue, green, or other colored stains on bathtubs are usually the residue from previous cleansers that were not rinsed off well. This is especially the case with porcelain and enamel bathtubs that have developed rough surfaces from years of scrubbing with abrasive cleaners. When a cleaner is used on these rough surfaces, the cleaner's dyes can get into the rough areas and harden, causing colored stains. For stains that have remained on the bathtub for ages, no cleaning agent may be enough, though a strong chlorine bleach solution may take the stain off; however, chlorine bleach is likely to further discolor the surface.
For mildew stains, use a brush to scrub the affected area with a mixture of ½ to 1 cup of chlorine bleach in a gallon of water.