The basic principle of preservation of historic memorabilia is do no harm. The following hazards are recognized as some of the most dangerous to historic memorabilia.
Too much light speeds deterioration of photographs, textiles and printed or handwritten paper, furniture, etc. Historic objects should be protected from excessive light levels, and especially from sunlight and florescent light, which contain high amounts of ultraviolet radiation–which is the most harmful form of light. Place furniture, antique quilts and other memorabilia out of direct sunlight and/or florescent light.
Too high or too low a temperature (or rapid temperature swings) can damage rubber, wood, metal, etc. Store or display historic memorabilia in spaces that have climate-control systems (heating and air conditioning). Do not store in sheds, attics and basements.
Humidity that is too high encourages pests and mold growth on paper, textiles and parchment, and promotes rust on metal. Humidity that is too low can cause objects to become brittle. Organic objects in particular absorb and release moisture depending on the relative humidity of their environment and need a stable humidity. Store historic memorabilia in an area that has a steady, constant humidity (45%–55%), and store or display historic materials away from heating and air conditioning vents.
Different types of historic materials attract different types of pests. Roaches and silverfish are attracted to paper and books. Moths are attracted to protein fibers such as silk and wool. Termites are attracted to wood. Conduct regular inspections of historic objects that attract pests.
Human beings are one of the greatest threats to historic objects, not only due to surface compounds, such as oil, sweat and make-up that they carry on their skin, but also because we continue to use historic objects. These oils and other surface substances are transferred to the object during handling. Wear cotton or nylon gloves when handling historic paper, textiles, photographs, and wooden and metal objects. Many objects are damaged because people handle them in inappropriate ways, such as trying on clothing, taking items to show-and-tell at school or even using them for their original purposes. All of these uses put undue strain on the objects and put them at risk for loss or damage.
CHEMICAL REACTION & AIR POLLUTANTS
Certain types of materials, such as metal and marble, react to chemicals present in the air. This is a particular concern for outdoor objects such as marble statuary, iron architectural elements, etc. Chemicals such as formaldehyde and acidic gases from wooden compounds can also harm historic objects.
Some objects that are composed of incompatible materials, such as wood and leather or wood and paint, have built-in deterioration risks. Conduct regular inspections of these objects for any changes in condition.
VARIOUS TYPES OF PRESERVING MATERIALS
1. Basic Preservation Techniques for Paper
Most paper in the last 300 years has been made from either linen or cotton rags or wood pulp. Rag paper has a low acid content and is much more stable than pulp paper. Wood-pulp paper, the kind used for newspapers, is usually very high in acid and deteriorates rapidly.
- Basic Preservation Techniques for Textiles
Textiles or objects made from woven fibers are among the most common types of artifacts found in museums or within a family. Most families have a treasured textile such as a quilt, wedding dress or tablecloth that has been handed down through the generations. Until the 20th century, textiles were made from natural sources, such as cotton or linen plants or sheep or silkworms. In the 20th century, synthetic or laboratory textiles have been developed such as rayon, nylon and acetate. Textiles (and the dyes used to color them) are very susceptible to damage from light, acids and pests.
- Basic Preservation of Metal Artifacts
All metal except gold is susceptible to oxidation or corrosion. Prevention of corrosion or oxidation is the primary goal in caring for metal artifacts. Most corrosion is caused by moisture, although certain chemicals can also play a role. The oils and acids that occur naturally on skin can be very damaging to metal artifacts. One of the simplest ways to help preserve your artifacts is to store them in a relatively dry environment. Typically, metal artifacts should be stored in living areas, which are much dryer then sheds garages or basements. Attics are generally too hot for most artifacts.
- Basic Preservation of Leather Artifacts
Leather is a difficult item to preserve; care should be taken to store in medium humidity and moderate temperature. Generally speaking, storing it inside your home is suitable. Most leather will stiffen over time; this is generally not a problem, as historic items should not be used. Take time now, while the leather is pliable, to support the item in a displayable manner. For example, lightly stuff the toes of shoes or boots to help them maintain their shape, use acid-free tissue; boot tops can be supported with acid-free tubes made from file folders. Do up all the laces and buckles.
- Basic Preservation of Wood Artifacts
Wood is a relatively stable material to preserve. Wooden artifacts can be maintained for years, provided that some basic care and attention is given to their preservation. Store wooden items in your home where they are protected from extremes of temperature and humidity. Avoid direct sunlight or bright light, which will fade finishes. Avoid all temptations to over-clean or refinish wood items.