Our first rule on polishing silver is to avoid it. Not because collection managers are lazy, but because each time we polish to remove tarnish, we rub away a microscopic layer of the material. Over time polishing can diminish and even deface the historical material. Most of us have seen incidences of this where the engraving on silver artifacts has become barely visible after many years of polishing. Silver plated objects can loose their shiny metal casings readily with polishing and reveal patches of copper or another base metal beneath.
Several storage materials can prevent tarnish by blocking sulfuric pollutants from coming in contact with the silver. 4 products are especially effective:
Still, even with methods to prevent tarnish, there are times when silver artifacts must be out on exhibit, outside of protective cases. Perhaps this is most common within historic house museums, where silver often gleams from table settings and sideboards. When polishing becomes necessary, collection stewards should use the gentlest methods and materials possible. In the past, our “Collection Care Basics” workshops have included practicing with silver plate utensils, and this activity has been one of the hands-on components participants have enjoyed. We have followed the directions outlined in the National Park Service’s Conserve O Gram on silver polishing. First wiping pieces down with cotton rags dampened with ethanol and then stirring a polish made from precipitated calcium carbonate mixed with distilled water to form a cream consistency. (Click here and scroll to page 3 for more complete instructions.) Other great online resources are two videos that the Nebraska State Historical Society’s GeraldR. Ford Conservation Center produced—one on polishing (solution varies slightly from the NPS recommendations) and another on applying microcrystalline wax as a protective coating.
Now, as our C2C project focuses more on disaster preparedness and recovery, our Basics workshop will concentrate more on storage methods as disaster damage mitigation. We will use the hands-on time previously spent on silver polishing to practice creating storage cradle mounts from ethafoam instead. We hope the online resources we have suggested, along with whatever personal guidance we can offer, will help you through the polishing process. NC metals conservator, Jane Bynon, is another local resource and is one of the few experts in the region who has the capability to lacquer objects–another tarnish-preventing option for silver on long-term display.
What methods for preventing and/or removing tarnish have been most successful for the collections under your care?
Posted on October 22, 2013, in cleaning, collections care, Connecting to Collections, conservation, historic houses, storage, workshops and tagged activated carbon, corrosion intercept film, Jane Bynon, Joel Lane House, Kathy Ruse, Pacific silvercloth. Bookmark the permalink. Leave a comment.