Conservation: Ceramics & Glass
To hold a piece of glass or ceramics is to hold a piece of our unimaginable part in history.
Ceramics can be classified into three groups which are defined by the clay, the temperature it was fired, and if a glaze was used. These are porcelain and stoneware, earthenware and terra cotta, and unfired clay. The method of making the ceramics will determine the method for conservation.
Out of the three, porcelain or stoneware has been fired at the highest heat and is, out of the three, the most nonporous. Earthenware and terra cotta have been fired at a medium heat making it porous unless it is glazed. This porous quality allows it to move between temperatures for cooking. Unfired clay is, in fact, fired but at an extremely low heat, and for this reason is water-soluble.
On the whole, the destructive forces to ceramics come from human error. How the piece is handled, stored and displayed is a priority. Besides clumsiness, severe change in temperature can cause a piece to break. Again, this is often by human oversight i.e. ovens, hot lights, or extreme cooling.
Regular cleaning can be performed, but with extreme care. As with any piece of value, any damage it incurs will affect its monetary value.
CARE AND CLEANING
- Dust ceramics and glass with either a clean cloth or paintbrush. Do not use any types of cleaning solutions
- Pieces that are in good condition but need a more thorough cleaning may be carefully washed with room temperature water
- For more intensive cleaning, contact a conservator
- Consult a conservator for appropriate light, temperature and humidity settings
HANDLING, TRANSPORTING and STORAGE
- Decide the value of your piece and whether it should be used everyday or not at all
- Never adhere stickers or tape to ceramics or glass, as they will leave a mark
- Be aware and thoughtful when you move a piece
- Be mindful of how the piece is held. Carry it firmly at its center of gravity, even tea- pots
- Separate any movable or unsteady parts and wrap individually
- Choose protective material that is appropriate for the pieces you are moving i.e. padding
- If the piece is to be stored for a long period, there are conservation quality materials available
- Stacking is never advisable
- Do not wrap ceramics or glass in newspaper, recommended instead is a flannel cloth, paper towels, polyethylene, acid-free paper or DuPont Mylar Type D
- Create a safe environment, one that is dust-free, stable, and not in direct light
- For shelves, research appropriate padding depending upon your pieces
- Do not use wool felt that attracts insects, or Polyurethane foam that is not conservation quality
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