People sometimes comment that my pewter is very shiny. New pewter is very bright. Over the years, as a pewter object such a wine goblet is handled, it will dull and become gray. This is not dirt.  It is an oxide on the surface of the pewter called a patina.  It can be rebuffed to its original shine if you wish.  This is my personal goblet, used for 25 years and never re-polished

For comparison, a new goblet.

Some pieces, such as vases, that are not frequently handled should stay bright for a very long time. Household dirt can be removed with soap and warm water. A high shine can be returned to the metal with any good metal cleaner. Very old pewter - over 150 years - probably contains some lead, and this will make the pewter dark.  If it has significant lead (greater than 10%), it may have a hard black scale on the surface.  I would suggest that you leave the cleaning of very old pewter to the professional. 

Some commercial pewter companies artificially age their pewter by chemically treating the surface to make the object appear old.  The problem here is that any scratch shows, as it appears bright. 

 Another problem you may encounter, specifically with some Dutch pewter manufacturers, is patches of darker metal.  These companies lacquer the finished product, and with time and use, the lacquer flakes off, allowing the underlying pewter to age.  The lacquer can be easily removed by wiping the piece with methanol (methyl hydrate) and soft cloth or tissue.  The piece may then be cleaned with polish or very fine steel wool, 0000 grade.

To keep your pewter looking good for many years, you should remember a few simple things:

• Do not put pewter in the dishwasher. It will discolour the metal.
• Do not let candles burn down below the lip of the candle holder unless you know it has been specifically designed for that purpose. Pewter melts at a low temperature.
• For the same reason, you should avoid putting your pewter teapot on the stove. I have repaired more melted teapot bottoms than I can count.
• Sap from cut flowers may stain your pewter, so do not put them in an open bowl. Placing flowers in a pewter vase is fine, as you will not see the inside the vase anyway.
• Also, do not leave acid fruit juices or foods in pewter for long periods of time, as this could discolour the metal.