Making it Shine

There is one unavoidable constant for any person who owns silver, tarnish. Whether its the cutlery you only pull out for Christmas dinner or a pair of earrings. Here in the museum we also have to deal with tarnished silver, most recently a silver tea set from the McCook House.

With as many objects as we have in the collections at the Ohio Historical Society and our affiliated sites, keeping every piece of silver properly polished is almost an impossible feat.  Over time, unpolished pieces build up a dark residue.  Silver is effected by the environment, particularly hydrogen sulfide, which causes a chemical reaction on its surface known as tarnish.  This discoloration begins with a milky white color, progressing through yellow and brown.  In sever cases, tarnish can appear nearly black.  This was the case with the McCook silver.

Badly tarnished piece of McCook silver prior to cleaning.

So how does a museum clean heavily tarnished silver?  That is something varies depending on the material (solid silver v. plated silver) and curator/conservator preference.  It should be said that there are many products available for silver cleaning.  For museum silver, I personally dislike using commercial treatments that can contain unwanted ingredients.  They can leave a residue that, over time, can built up and cause harm to the collections and are often far too abrasive, leading to damaged or lost silver.

The first step in any cleaning or conservation process is observation.  You have to know what is going on with the piece to know how to treat it, and its important to look beyond the obvious.  Yes, the set was heavily tarnished.  What else?  Looking closely, there was observable silver loss on raised decorative elements throughout the set.  This meant that we had a damaged silver plate, which is more susceptible to further loss if the cleaning process was too abrasive.  So what did we do?

Calcium Carbonate and deionized water being mixed into a paste.

Chalk!  Well, close.  Calcium Carbonate is a soft abrasive, meaning it will affect the tarnish without risking unnecessary damage to the already compromised silver plate.  This compound can be purchased though numerous vendors online at very reasonable costs.  To make the cleaning paste, you need to combine your calcium carbonate (a white powder) with deionized water until it is the consistency of marshmallow fluff.  You dont want it too runny or too firm.

McCook silver, mid cleaning.

Using soft cloths and cotton swabs, we proceeded piece by piece.  Apply, rub, wipe away.  Repeat.  Repeat.  Repeat.  Because the cleaning mixture is such a mild abrasive, and the tarnish so heavy, the entire process took two staff members one full work day.  Long, time consuming, but oh so satisfying.  Once the tarnish had been removed, detail work could begin.  Bamboo skewers (found in the grocery store) and soft bristled brushes helped us remove the excess mixture from the various nooks and crannies.

Make sure to wear clothing that you wont mind getting messy. Cleaning silver can be a dirty job.

The last step is a good solid polish, using a silver polishing cloth (or rouge cloth) and elbow grease.  You never want to submerge silver plate completely in water because the base metal can corrode.  Buffing with the polishing cloth also helps to dry the small amount of water used in the calcium carbonate mixture.

Silver polishing, before and after. What a difference a little TLC and Chalk can make!

Once the silver shines again, regular polishing with the cloth will help prevent similar build ups.  I recommend once every 2-4 weeks.

Elizabeth Higgins
History Curator.

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10 Responses to Making it Shine

  1. Just Plain Jim says:

    Sure beats Lava soap and OrangeGlo with pumice ! ☺

  2. Muskco Guy says:

    I like practical posts like this one that give advice I can use at home and in our county museum. You could keep this line of thought going by telling how to polish brass and how to keep glass from developing a cloudy film.

  3. Wow, this was really interesting! I’m an archives person so I don’t know a lot about taking care of museum objects. THanks for sharing!

  4. Katherine says:

    Great advice, from a reliable source. Thank you!

  5. Mae Ella says:

    I much prefer the scientific method of CHANGING the silver sulphide into aluminum sulphide without removing a speck of silver from the object. Here is a link that provides this:

    http://scifun.chem.wisc.edu/homeexpts/TARNISH.html

    It is basically a nonintrusive soak and NONE of the silver is removed . We older folks all saw the commercials for the aluminum sheet of “magic” that helped do this being sold in the 80s. It is very simple to do and I have no idea why this “scrub the silver off of the historical object” method is even posted.

    • ohiohistory says:

      Mae,

      When dealing with plated pieces, especially those that are already showing signs of lost plate, I do not like to fully submerge them in water. Particularly tea sets and other objects that have an untreated or unplated interior. These are hard to properly dry after being fully submerged which can lead to mildewing, further tarnishing, and in some cases rust. The Calcium Carbonate method cleans in small, controlled sections with a very mild abrasive (so mild it often takes multiple rounds of cleaning to remove all of the tarnish on pieces that were as heavily tarnished as these) and no chemical residue. Ideally, silver should be polished with a jewelers cloth on a regular basis to prevent tarnish buildup and therefore eliminating the need for more intensive cleaning.

      E. Higgins
      History Curator

  6. Rebecca says:

    I’m looking to buy some of this calcium carbonate powder and cannot find it locally. Online there are a few different kinds, calcium carbonate – limestone powder, calcium carbonate food grade powder, Pure Snow white 100% calcium carbonate power…etc. which one should I be looking for?

    • ohiohistory says:

      Hi,

      I consulted one of our object curators and what he says you are looking for is a food grade, powdered chalk. Here is some additional information:

      For most polishing, we use fine calcium carbonate, CHALK (“whiting”), worked into a slurry or runny paste with equal amounts of ethanol (denatured alcohol or ethyl alcohol) and distilled water. The paste is rubbed across the surface working a small area at a time with cotton balls or clean, cotton rags. Detailed areas may be polished with Q-tips or with cotton wadding on the end of a sharpened bamboo skewer. Depending on the design of your object, it may not be desirable to OVER-CLEAN every crevice, as this decreases the overall contrast of the detailing. It is important to remove all residual polish with distilled water. Drying may be accelerated by adding ethanol to the rinse water, or by giving the object a final wipe with ethanol.

      L.Wood

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