Attics and Basements and Closets, Oh My! Part 15: Metal Jewelry

While those of us in the conservation department grapple with the many challenges facing our society, we are finding comfort in our family heirlooms and treasures—many of which require our attention. We understand that like us, many of you may be turning to your family treasures for comfort during these trying times. Thus, the conservation department would like to share tips on ways to care for your personal collections and assure you that we are here to support you and the collections that you hold dear. 

Each week a different student from the Winterthur/University of Delaware Program in Art Conservation will address ways to care for the collections in your cupboards. This week’s post focuses on the care and storage of metal jewelry and was written by rising second-year Objects Fellow, Nylah Byrd.

Metal Jewelry 

Jewelry can be made of a multitude of materials: metal, wood, plastic, glass, ceramic, etc. While this blog post will focus on the care and storage of metal jewelry, please see the resources listed at the bottom of this blog post for information on other potential jewelry materials.

Handling of Metals

For preserving jewelry at home, the first step is to decide if the object is a “use object” meaning jewelry that will be worn. For jewelry that is still in use, the handling decisions are up to the wearer. Jewelry in museum collections are no longer use objects and therefore are handled differently. It is important to wear gloves when handling metal collections, as oils and salts from our skin can damage the metal. Nitrile gloves are preferred, but clean cotton gloves can be used. It is important to clean the cotton gloves regularly because cotton absorbs oils from our skin and will eventually transfer the oil onto the metal. Wearing gloves when handling metal also serves to protect the handler from potentially harmful materials being deposited on the skin, especially if the metal object exhibits corrosion.

Storage of Metals

Containers: Jewelry boxes and other jewelry furniture are perfectly acceptable ways to store use objects. When storing metal jewelry that is no longer to be worn or used, it is important to ensure the objects are separated from one another. Spontaneous corrosion can occur if objects composed of different metals are left in contact with each other for extended periods of time. Museum metal objects not exhibiting active corrosion are ideally stored in metal cabinets with powder coatings. Polyethylene containers and bags, food grade (clean) polystyrene containers, and acid free unbuffered paper and board may also be used. When storing metal jewelry at home, wooden containers and shelves are viable options provided there is a barrier between the wood and the metal. Acid free unbuffered paper and unbleached cotton or linen fabrics are excellent barrier materials. 

​Corrosion: There are two types of corrosion: passive and active. Passive corrosion creates a protective layer on the metal. Active corrosion continuously degrades metal. It is crucial to keep metal objects away from water, salts, and acids to avoid active corrosion. An ideal metal storage environment has a relative humidity (RH) between 35% and 55%. Metals exhibiting active corrosion require an even more controlled environment with as low relative humidity as possible, and low to no oxygen. Corrosion is composed of metal oxides, and if there is no oxygen in the environment, the oxides cannot continue to form. Here are some metals and common causes of their corrosion:

• Copper alloys: Ammonia, chlorides, sulfide gasses
• Iron: RH over 65%
• Lead: Organic acids (e.g. acetic acid commonly known as vinegar)
• Metal plated objects: Salts, organic residues, contact with other metal plated objects
• Silver: Sulphur (which is found in air pollutants, contaminated water, rubber, certain paints, and some textiles)

If you have a metal object at home that is actively corroding, separate it from the other metals and contact a conservator.

We all have jewelry we cherish and wear. We hope these tips will keep yours sparkling for many future generations. To find out more about other jewelry materials: 

• Identifying active corrosion
  
• Metals
  
• Wood
  
• Plastic
  
• Glass
  
• Ceramics
  

We hope you are enjoying these entries in our series focused on caring for your family heirlooms. This series will continue throughout the summer and cover a variety of items and materials. If you have any comments on the series thus far, including materials you’d like to see covered in future posts, please email us at art-conservation@udel.edu. The previous posts in this series are available on the Department of Art Conservation website here.

You are in our hearts and minds as collectively we face many challenges. We hope you and your loved ones are safe and healthy. When we emerge from this global crisis we must and will rely on art and culture, preserved for today and for future generations, to foster joy, well-being and hope. We encourage you to visit our web site for regular updates on our department of art conservation and news coverage of our treasured students and alumni at home and abroad.