How To Identify And Care for Sheffield Plate   

There were no laws governing the marking of plate wares. Old Sheffield Plate, all of which was made before 1840, is usually unmarked or has the maker's name or symbol only.  Plate wares marked "A1," "EPNS," "Sheffield," "Silver on Copper" or "Silver Soldered" are modern electroplate.

 1834 Sheffield Marks, the crown being Sheffield city mark.

It is most likely Sheffield Plate if . . .

the piece is in good condition but has visible seams, folded over edges or if decorative mounts are lapped over the rims it is Sheffield Plate. This was done to prevent "fraying" of the silver - copper sandwich. (The edges of electroplated items are seamless because silver is deposited over the entire surface.) The decorative mounts (handles/rims/feet) were filled with lead and so these pieces are heavy.

red copper shows through.

rubbed-in shields can be detected by breathing on them. (The shields were made of 92.5% silver and tarnish at a different rate.)

Care of Cleaning of Sheffield Plate

Fused plate should be cleaned as little as possible since cleaning causes abrasion of the silver surface.  If necessary use non-abrasive polish with a soft cloth. Fused plate should never be "restored" by electroplating as this gives it a silver coating of an entirely different nature.

Old Sheffield Plate, Annee Bambery, Shire Publications

By definition, Sheffield Plate consists of a copper core. Due to over-use, over-cleaning or cheap manufacturing, the silver plating rubs away and caused "bleeding" of copper though the silver. Often, wear appears on areas of a piece that were rubbed frequently such as handles and feet When caring for Sheffield Plate, it is necessary to clean pieces occasionally, being cautious not to over-clean. Overall, a good cleaning with hot, soapy water will maintain a piece without damage. For older stains and build-up, a gentle scrub with an ammonia and whiting paste will work. Using a soft silver cleaning brush and scrubbing in a circular motion will remove most debris. For tougher spots, a piece can be treated with silver dip, a clear, powerful chemical that should release stubborn grime. Polishing Sheffield items can be done with any polish that does not contain harsh abrasives.

Abstracted from http://www.rauantiques.com