We recently partnered with Congregation Beth Torah’s Sisterhood to present Judaica Roadshow, our spin on the network television series of a similar name. While we mimicked some aspects of the familiar format, we structured our program to fit our community, and included preservation and care advice to promote longevity of the cherished items. The items selected fell into four preservation categories: silver/metal alloys, books/paper, oil paintings on canvas, and glazed ceramic. 

Read below to learn about how and why these types of objects and materials age the way they do and what you can do to care for them. 

Silver and Silver Alloys

Silver tarnishes due to a process called oxidation. Oxidation is caused when an element, in this case silver, reacts with atmospheric compounds, such as (but not limited to) sulfur, on a chemical level. This is what creates the layer of discoloration when silver sits unused for long periods.

When handling silver artifacts, use clean hands, clean cotton gloves or clean nitrile gloves to minimize the transfer of acids and oils on our hands that accelerate oxidation and etching.

There is discourse in the preservation community regarding how and when to clean silver. Our recommendation is to clean silver judiciously. When you clean silver, you are effectively removing a layer of the artifact. Over time, this wear can weaken the artifact, increasing the likelihood of physical damage/alteration and cause loss of detail. It is easier for you, and better for the object, to maintain a cleaned surface than it is to wait for an object to severely tarnish before cleaning. However, if your silver is already tarnished and will likely remain in storage, it may be advisable to leave that stable layer of tarnish in place, especially if details are already obscured due to wear. 

Store silver in a cool, dry place where fluctuations in temperature or humidity are minimal. Silver tarnishes more rapidly in hot and damp environments. Package silver in silver cloth, or unbuffered acid-free tissue paper and a polyethylene zip-loc style bag. Silvercloth has particles of silver or other compounds that absorb atmospheric pollutants before they have a chance to interact with the surface of the silver object. Acid-free tissue works in a similar fashion, providing a barrier that will also slow exposure to air and its compounds. Avoid storing in cardboard or other types of plastic, as their inherent composition – the chemicals they are made of – can accelerate and worsen oxidation. 

If the silver artifact is on display, place it in a location out of direct light and with consistent temperature and humidity. An air-tight cabinet is ideal, but not always practical. If you wish to keep the item free of tarnish, dust and polish regularly with a soft cotton cloth or polishing cloth while wearing gloves. This will not prevent oxidation, as that is unavoidable, but it will help to slow the process and maintain the item’s luster. One option to protect the piece is to consult a conservator about having the artifact cleaned and coated with an archival lacquer, such as Acryloid B-72 – a long-term, but impermanent solution. You can also purchase activated charcoal and other anti-tarnish inserts that work to absorb harmful pollutants for short periods of time.

It is also important to consider any wood the object is around. Wood should be well-sealed with a varnish that is archival quality, such as polyurethane. Natural compounds in wood, as well as chemicals in stains and some varnishes can accelerate oxidation. 

When cleaning silver, if you choose to do so, use a gentle phosphate-free detergent, as phosphate can cause discoloration on the surface of silver objects. To polish, a mildly abrasive paste of baking soda and water is recommended. Gently scrub in circles, rinse well. Dry completely with a soft cloth. 

Books

When considering the needs of books, many factors must be considered, including the various materials that make up the pages, binding, and covers, how those materials interact, and how that may impact how a book ages. Books are prone to aging – predominantly discoloration, embrittlement, and weakness is binding materials. The needs of historic books vary based on the composition – the types of materials used to create the book. Leather, paper, board, adhesive, and cotton-based thread are most often used, but you may run into vinyl covers, or covers inlaid with metal or even precious/semi-precious stones. The composition of inks varies substantially, as well.

Handle historic and delicate books with clean hands or well-fitting nitrile gloves. Dexterity is important when handling books because pages may be brittle and prone to loss. You may use a mini-spatula or letter opener to help turn pages if the edges are particularly delicate. Always support the spine and never open the book flat on a table. This will accelerate any separation of the binding materials. 

Store books away from high heat and fluctuations in humidity, as well as away from places at risk of water damage, such as basements or near pipes. Paper and paper-based materials are hygroscopic, meaning they absorb and release moisture depending on the surrounding environment. This causes changes on the molecular level, weakening pages and binding materials over time. Adhesives are also sensitive to fluctuations and can fail more rapidly when exposed to extremes. Leather can become brittle, or begin to secrete natural emollients when stored improperly, while vinyl can become brittle and flake or break apart easily. Inks may fade or bleed when exposed to high temperature or humidity. Chemicals in inks, pages or paper-based covers, and those used in leather tanning processes off-gas and often lead to discoloration. This is why the pages of many aged books are yellow or ochre in color. Overall, books are prone to pests such as (but not limited to) mold and silverfish; moisture makes the environment even more inviting. 

If displayed on a bookshelf or similar case, place the book out of direct sunlight. Prolonged exposure to light of any level can cause the cover to fade; bright/direct light will speed up the process. Heat from direct light can also compromise any adhesives.

Store small and medium books vertically, how you would orient them on a shelf. Store large volumes, especially those with soft covers flat to minimize warping and separation. Particularly delicate volumes can be protected from further damage by storing in specialty phase boxes, or wrapped in archival tissue and then placed in an acid-free box or zip-loc style polyethylene bag.

Oil Paintings

Every kind of art, every kind of painting will have a unique set of needs. Oil paintings are among the more stable, but there are still steps you can take to ensure longevity. The most common cause of damage to an oil painting is improper handling and storage, but they are also sensitive to other factors in the environment.

Always handle oil paintings by the frame or by the strainer (the support the canvas is stretched around) with two hands on the left and right sides. Never carry with one hand on a single side. Wear gloves or use clean hands if any part of the surface/paint needs to be touched for any reason. If the frame or strainer are unstable (moving at joints when handled) or the canvas is flagging (loose on the strainer), consult a framer or conservator for stabilization.

When considering where to hang an oil painting, factors such as light and humidity levels should be considered. Oil paints themselves are not prone to fading, but they are impacted by the heat direct or bright sunlight and incandescent lights generate, as are their canvas/board and frame. The canvas, board, and frame will also be impacted by fluctuations in humidity, expanding and contracting, which can lead to cracking or delamination (separation of the paint from the canvas or board). 

Store oil paintings vertically with the face protected by a plain cotton cloth with the face of the artwork positioned in such a way that no other objects will come in contact with or lean on the face of the painting. If anything leans on canvas, it will lead to stretching, which compromises stability and integrity over time, leading to cracking and loss on the surface. Ideally, paintings will be stored in slip cases, shadow boxes, or crates, depending on the size and value of the piece, as well as storage space. 

Consult a conservator when it comes to cleaning oil paintings. The process generally includes solvents that may be harmful in the home environment. 

Glazed Ceramic

Ceramics are among the most stable and easily preserved objects in home collections. Their biggest risk factor is physical damage from accidents and improper handling; however, they can be affected by heat, humidity, and moisture. 

Most glazed ceramics can be handled without special tools such as gloves, but ensure the object and your hands are dry and free of substances that can make the object slick to reduce the risk of dropping. Always handle with two hands for greater stability when transporting

Some historic and antique glazes include toxic metals or other minerals that can be harmful when handled, so it may be advisable to consult an expert or do personal research to learn about what glazes a producer may have used in a certain timeframe. Generally, these glazes have a luster-type finish, appear to be gilded (this does not include gold-toned details on china), or have very saturated hues. When in doubt, wear gloves, and do not use these vessels for food or beverage.

Over time, ceramic glazes can age and crack, a condition called crazing. Crazing is caused by the natural composition of glazes, as well as exposure to temperature extremes, moisture, and handling. When crazing occurs, more moisture can reach the ceramic body itself, which can lead to further delamination or loss of glazed areas and an interaction called spalling, which is when minerals in the clay body leach to the surface. Oxidation can also occur if iron or other minerals are present in the clay body and exposed to water and air. Moisture in the clay body can also lead to cracking, though cracks are most often caused by extreme fluctuations in temperature and mishandling. 

Store or display the object in a place where it is unlikely to be bumped. If your ceramic item is known to be food safe, you can clean with soap and water and dry with a soft cloth. Avoid using anything abrasive, as it can accelerate wear to the glazed surface. If the object is decorative, clean by dusting with a soft cloth and avoid use of water. 

Additional Resources are linked below:

Silver Care – Henry Ford Museum

Caring for Metal Objects – Canadian Conservation Institute

Preserving Books – National Archives

Caring for Oil Paintings – Guardian Fine Art Services

Caring for Paintings – Candaian Conservation Institute

Care for Ceramics and Glass – Candaian Conservation Institute

Ceramics – Western Australian Museum

As promised, Jessica’s favorite mini-spatulas