To avoid this, do not use wire brushes or steel wool to clean a porcelain sink. These are far too abrasive and will leave scratch marks. Any stain or mess that needs to be cleaned start by washing it with hot water, a soft sponge, and dish soap.
Abrasive tools: Abrasive tools like scouring pads and steel wool could cause unsightly scratches to form on porcelain sinks. Abrasive cleaners: Abrasive cleaners that contain harsh chemicals can stain, scratch, or damage the finish on porcelain sinks.
Steel wool scrub
Get a 0000-grade (the finest grade) steel wool. Since steel wool is such an abrasive product, you can either use it alone or in addition to borax + vinegar +/or baking soda for better results. 0000-grade steel wool is recommended as it's less likely to scratch up the inside of a porcelain toilet.
Hydrogen peroxide, the active component of oxygen bleach, gives baking soda an added punch to clear any yellow stains. For antique or colored porcelain, hydrogen peroxide and oxygen bleach are the most effective household cleaners for tough stains.
A baking soda and vinegar solution is perfect for cleaning a porcelain sink and removing stains. Make a paste out of the two ingredients and use a soft-bristled brush (such as an old toothbrush) or cloth and your finger, to apply and scrub the stained area.
For white porcelain only, bleach can be used to remove stains; never use chlorine bleach in colored or vintage porcelain, as it can damage the finish. For both white and colored porcelain, liquid oxygen bleach—such as hydrogen peroxide—is a good alternative.
Many homeowners ask if Magic Erasers® can be used on porcelain or if they will damage ceramic tile. The good news is that they can be safely used on ceramic tiles and porcelain, so you have nothing to worry about if you plan on using them this way.
Use on most bathroom surfaces including: porcelain, ceramic tile, shower doors, sinks, bathtubs, white grout and caulk, toilet bowls, and fiberglass. Will not remove rust. Do not use on vinyl, natural stones, mirrors, plastic laminates, wood, fabrics, painted, coated or sealed surfaces, colored grout or wall coverings.
Don't use steel wool on plastic surfaces or food storage containers—these will easily scratch up and make for breeding grounds for food stains and bacteria. For cleaning these bins, stick with warm soap and water. For targeting tough stains, try using diluted white vinegar and let your containers soak for a few hours.
Abrasive cleaners such as scouring powders, white vinegar (or other cleaners with a high acidic content), and steel wool should all be avoided, as they can damage the finish.
Never use metal utensils or steel wool on Enameled Cast Iron, as this will scratch the glaze and damage the smooth surface. Instead, reach for a silicone or wooden utensil to stir, and a sponge to clean (the abrasive side of a sponge is fine, just be gentle).
Though popular for being gentler alternatives to harsh chemical cleaners, baking soda, Borax, and even salt can harm the finish of your porcelain fixtures. As gentle as they are, these compounds are still abrasive and will scratch your finish, especially with regular use.
For white porcelain only, bleach can be used to remove stains; never use chlorine bleach in colored or vintage porcelain, as it can damage the finish. For both white and colored porcelain, liquid oxygen bleach (such as hydrogen peroxide) is a good alternative.
Some sinks are solid porcelain, but most have steel or cast iron core covered with a baked-on porcelain finish. Heavy or sharp objects dropped into a porcelain sink can chip or scratch its surface.
The best way to clean your porcelain kitchen sinks is by using bleach. Spread the cleaner on stains and let it sit overnight, then wash away in the morning. The stains in a porcelain sink can be removed using white vinegar. This method will also sanitize your sink and remove any harsh smells, making it clean again.
Just a simple mixture of baking soda and vinegar will take away all gunk and stains that you could throw at your sink. I suggest making a paste in the sink, so you can best gauge how much you need, but just sprinkle baking soda over the entire bottom surface then drizzling a light amount of vinegar over top.
You can use Scrubbing Bubbles multi-surface bathroom cleaner on glazed ceramic tile, stainless steel, chrome fixtures, fiberglass, vinyl, glazed porcelain, glass, laminate, Corian, sealed granite and quartz surfaces.
First, wet down the sink and sprinkle baking soda onto a moist sponge. Then scrub the sink with baking soda. Next, pour home hydrogen peroxide on the sponge and rub all over the sink. Wait about 15-20 minutes, and then rinse the whole sink.
Sprinkle the marks with acidic cleanser powder.
The most popular acidic cleanser for metal marks is Bar Keeper's Friend, although a generic ceramic stove top cleaner or Rust Stain Magic are good alternatives too.
For a sink that requires major work, a repair kit made specifically for porcelain sink restoration may be worth the cost. These kits typically include an abrasive cloth to buff the nick and surrounding space, and a gloss or glaze to fill the damaged area.
The brown stain is from a large amount of iron in your water. It is closely related to simple rust that you see on metal, which is iron oxide. Your water probably comes from groundwater that filtered through rocks containing iron-rich minerals on its way to the well.