Porcelain is a type of glass that is relatively non-porous but that still can absorb certain stains. Porcelain is also relatively hard, but it can get scratched and nicked with very sharp or very heavy objects. Protect your porcelain sink by taking several precautions to make sure it doesn't get damaged. This is especially important if you have an old porcelain sink, as these are generally softer and more susceptible to scratching and staining.
Clean the sink with non-acidic cleaning solutions. Acid cleaners such as muriatic acid or even white vinegar can etch the porcelain surface. Instead, use pH balanced cleaners or alkaline cleaners such as baking soda.
Scrub the sink with very mild abrasives such as baking soda paste or soft-bristled brushes. Harsh abrasives such as steel wool or stiff-bristled brushes can scratch porcelain.
Rinse the porcelain sink thoroughly with water after using any cleaning solution. This will prevent cleanser residue from eating away at the surface of the porcelain and causing very small, but eventually noticeable, scratches.
Don't store heavy objects above porcelain sinks. This includes heavy toothbrush holders, soap dishes or candle holders. Instead, store these items on shelves in areas that are not over the porcelain sink.