May 6, 2014 at 2:01 pm #131984Shauniece HeusnerMember
We have just come into custody some silver antique items from the 1800’s- one being a silver pieces-of-eights coin. What would be the procedure for cleaning and care of these silver pieces?
May 7, 2014 at 8:56 am #131991Christine ClementsMember
I recently was tasked with polishing some silver artifacts, some from the 1800’s. The method that my curator and I used was a non-abrasive method of polishing.
We had a plastic container, big enough for the soup ladle we were polishing. You boil water, put a piece of aluminium foil in the bottom of the container and pour salt and baking soda on top. Then add the water and place your artifacts in. The tarnish comes off and sticks to the aluminium foil. Then you can take out the artifacts and lightly buff and dry them.
It was a really effective method!! We cleaned a trophy that hadn’t been cleaned since we got it, it was almost black, and now it is bright and shiny again!!
Hope this helps!!
May 7, 2014 at 10:50 am #131990Helena JaeschkeMember
Whilst the aluminium foil/sodium chloride/ sodium bicarbonate method is very effective at removing tarnish it will leave deposits behind in the small cracks and interstices of older metal items which will lead to further corrosion in future. Please don’t use it on anything which is not a modern item of your own which you don’t intend to pass on to others.
Archaeological silver, such as a coin, is seldom safe to treat by immersion in a liquid, as it will have holes and weakened crystal boundaries and some areas may be more severely affected than others. Liquid treatments are not easy to control (or undo). This includes cleaning agents such as dips or foams which are applied to the surface, but which will penetrate into weakened areas which may be invisible to the naked eye.
The safest way to clean it is to take it to an archaeological conservator who will examine it under a microscope and clean it using controlled, localised methods, often by physical, not chemical cleaning.
Only when you have asked an archaeological conservator and found out whether the cost of treatment is beyond your budget (and that of any potential donors, fundraising activity etc) and been assured that the item is of relatively little historical importance should you consider cleaning it yourself.
First you must make sure you understand what it is you are removing and why. Then having satisfied yourself that you are not removing evidence of the object’s past, an intentional treatment or a modern disguise (like the dark brown and green paint or wax sometimes applied to bronzes to make them look antique), document the item thoroughly with photographs and description. Cleaning is irreversible.
Then you could try a Goddard’s Silver Cloth http://www.goddards.com/html/products/productDetail.php?id=8 or similar product, taking great care of the surface. You can use small pieces of the cloth wrapped around a toothpick to gently clean details in the decoration. This will remove much of the corrosion which is tarnishing the surface. Keep watching the surface in case you uncover some unexpected change.
When you have finished, document what was done to the object and preserve it as part of the object’s history. Keep the item in clean, dry conditions, away from sources of sulphur or acidic materials which could cause further rapid retarnishing.
Hope this helps
May 7, 2014 at 11:38 am #131989Adrienne BerneyMember
Thanks for the helpful information. Do you consider Goddard’s to be a better method than the mixture of precip. calcium carbonate and distilled water that many other conservators have advised? (Including an NPS conserve-o-gram and in this video: http://www.savingtreasures.org/)
May 8, 2014 at 11:19 am #131988Carol BergeronParticipant
My advice comes from my many years as an antiques dealer rather than a conservator. I have used most of the processes described and I have learned that the calcium carbonate and other dip processes will remove the important characteristics of the silver piece. Depth in a design is emphasized by the “natural darkening in the recesses of ornamental pieces and engravings [and/or] A factory-applied chemical used to darken the recesses of a design to enhance its details and give it a three-dimensional look.” http://www.hermansilver.com/glossary.htm This is an excellent site to learn much more about silver and its car. I will say I use a cream polish, either Wrights or Goddards.
May 8, 2014 at 2:10 pm #131987Lynne IrelandMember
Here’s info from the Gerald R. Ford Conservation Center that includes video links. Plus check out Deborah Long’s C2C webinar http://www.connectingtocollections.org/webinar-care-of-metal-objects/
May 8, 2014 at 2:17 pm #131986Lynne IrelandMember
trying again to post link:
May 8, 2014 at 6:46 pm #131985Ronald HerouxParticipant
Coin collectors generally disapprove of cleaning of coins – it diminishes their numismatic value.
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