Attics and Basements and Closets, Oh My! Part 12: Ceramics

​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 caring for ceramic collections and was written by rising second-year Fellow in Objects Conservation Abigail Rodriquez. 

Ceramics 

Composition

Ceramics are ubiquitous in many aspects of our lives, from tilework and flowerpots to fine dinnerware and decorative arts. Categorized as earthenware, stoneware, or porcelain, ceramics have three main clay bodies that vary in their degree of porosity, or literally how easily liquids are able to pass through them, and durability. These categories are defined by the firing temperatures and constituents of the clay. 

• Earthenware ceramics are fired at comparatively lower temperatures (up to 1150°C) and range in color from creamy whites to red-browns. They are porous by nature and have thicker walls that add to their overall strength. 

• Stoneware ceramics are fired at mid-range temperatures (around 1200°C-1300°C) and vary in color from light grays to dark reds. They have strong semi-porous bodies. 

• Porcelain is fired at the highest temperatures (above 1300°C) and is non-porous – the clay body is vitreous and ranges from white to blue-gray. 

The porosity of your ceramic is key when considering the penetration of moisture, dust, and other ambient materials into the body of your object. 

Ceramic bodies can be left plain or be decorated with a slip, glaze, paint, enamel, or gilding. Glazes provide both a decorative finish and an impermeable coating to strengthen a ceramic body, effectively making the object suitable for carrying liquids. Knowing what kind of decoration a ceramic has on the surface is critical when considering how to handle, display, store, and clean the object. 

Handling

A common cause of damage for ceramics is fracture and loss from careless or boisterous handling. Some key elements to consider when handling ceramics are outlined below:

• Think through the handling process ahead of time and prepare for each step.

• Always examine the object beforehand, noting any unstable repairs, loose parts, lifting areas of decoration, hairline cracks, or vulnerable appendages.

• Consider whether or not to use gloves.

  While most ceramics can be handled with clean, dry hands, unglazed ceramics, and ceramics with gilding or luster should be handled with a barrier layer such as a clean lint-free cloth or nitrile gloves to avoid damaging the surface finishes. Nitrile gloves can be ordered online or purchased at many pharmacy and home supply stores. 

• Support the object evenly with both hands, and avoid placing weight along rims, handles, or knobs as these are areas that could be weak or have previous repairs.

• Use soft padded containers for the transport of ceramics objects from one location to another.
  

​Display

Ceramics are generally resilient with minimal sensitivity to fluctuations in humidity, temperature, and light. While this may be the case, it is always best practice to avoid temperature extremes, especially rapid changes, as this can cause differential expansion and contraction between ceramic bodies and decoration layers and subsequent breaking or cracking. 

An ideal display environment for a ceramic object is one that is secure from physical damage and protected from major dust accumulation. Storage on shelves or in cupboards that are not subject to major vibrations are great locations for ceramic objects. Shelves can even be lined with a non-fibrous padding such as a polyethylene foam sheeting for additional support. 

Dusting

Even ceramics on shelving may need a little TLC from time to time, and gentle dusting with the right tools will do the trick. It is important to carefully examine the ceramic and surrounding area before dusting to minimize potential damages. Handling should be minimized during dusting, if possible. 

For stable, glazed surfaces, a lint-free cotton duster can be used to wipe down the surface. For un-glazed or intricate surfaces, a dry brush can be used with a vacuum to lift the dust. The nozzle of the vacuum should be held away from the surface of the object while the dust is brushed towards the suction.  

Additional resources on  dusting ceramics can be found here: https://www.nps.gov/museum/publications/conserveogram/08-01.pdf

From everyday domestic objects to treasured art objects, the care of ceramics can be as simple as keeping handling to a minimum, using shelving to minimize dust accumulation, and regularly dusting stable surfaces. Following these careful steps, ceramic objects can be preserved for many years to come.

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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.