One of the safest, most effective means of protecting a document from harm is through encapsulation. Encapsulation allows you to view and handle a document without exposing it to hazardous elements. The process involves the positioning of a flat document between two pieces of polyester film that are then sealed on all sides.

Clear Plastic Films
There are a variety of clear plastic films on the market. Some contain plasticizers or surface coatings that are inappropriate for encapsulation. They can and will react with the items they come in contact with, doing more harm than good. If you are planning to encapsulate, be certain you are using Melinex or other brands of polyester determined to be inert. The material you choose should be free of plasticizers, or surface coatings of any kind.

Sealing
Sealing the polyester also involves specific methods and materials. Heat sealing and ultrasonic welding equipment is available for adhesive-free sealing of polyester. However, the price tag for this type of equipment may be prohibitive for the average collector. The alternative is to use a double sided pressure sensitive tape. The tape should feature a stable acrylic adhesive such as 3M's No. 415 Polyester Transparent Tape.

Pre-Formed Encapsulation
An alternative to buying expensive equipment or using adhesive tape is to purchase pre-formed encapsulation units. They are available in sizes and styles that will accommodate items of just about any size. If you plan on encapsulating a small quantity of items, this may be the most economical and time saving approach. Should you choose this route, be sure, once again, that the encapsulation units you purchase are made from an inert polyester such as Melinex.

Research has shown that encapsulation can increase the rate of deterioration of an acidic document. A qualified conservator can determine if a document is acidic and also perform a deacidification treatment if it is required. 

Besides the protection factor encapsulation provides, static electricity inherent in polyester film will hold a document in place. Worn and fragile documents benefit greatly from this static charge since it helps hold torn pages together. The downside is the same charge will attract some mediums, such as charcoal or pastels, away from the document. A qualified conservator can determine if a particular document should or should not be encapsulated.

Once an item is determined to be safe for encapsulation, and the procedure is complete, your document is safe from dirt, pollution and fingerprints. Encapsulation will not, however, protect your autographed document from the hazards of ultraviolet light, and temperature and humidity extremes. Your encapsulated document should be stored out of the light in a climate controlled environment. Ideally, it should be stored flat in an archival quality box.