By Sharon Partridge for the Colorado Preservation Alliance
Encapsulation does for a single page what phase boxes do for books and pamphlets. In addition to protecting the item from the environment, encapsulation makes it possible to handle extremely fragile paper. Placing the document between sheets of inert (chemically inactive, doesn’t interact with the paper) plastic sets up a static field which makes use possible. While this does not decrease the brittleness of the paper, the plastic does prevent further breakage. Remember that you don’t remove the document, so multiple-page items must be disbound and each page encapsulated.
Lamination, in contrast to encapsulation, involves the use of chemical adhesives which touch the paper and the plastic used, vinyl, has also been a culprit in actually accelerating paper destruction. Unlike lamination, encapsulation is an easily reversible process and therefore doesn’t eliminate future choices for care.
It is better to do any deacidification, mending and cleaning (Scum-x works well for cleaning) before encapsulation, but if that isn’t possible, at least the paper will not get any worse and it is always possible to do these procedures later.
Inert plastic, usually polyester, in a weight comparable to the paper weight (usually 3 mil for small documents) is folded in half and cut to allow half-inch borders around the three open sides. (You may want to be more generous with the borders until you become adept.) Mylar (Dupont) is one trade name for polyester. Place double-sided tape (3-M No. 415 is a representative tape) on a side touching the fold to form an “L” or corner. The tape should not touch the document so leave a quarter-inch space between the paper and the tape. It is also better to leave a space between the tape and the edge of the plastic to avoid dust and dirt sticking to the tape.
Make sure to leave about a quarter-inch gap where the pieces of tape meet at the corners. This “breathing space” helps prevent a build-up of gases from the paper.
Place the document in the corner and tape your third and fourth sides. A weight to hold the free corner of the top layer of polyester out of your way while you are taping the bottom is a great frustration-reducer. Remember that the tape should not touch the document (this is easier than it sounds). Gently using a roller from the finished corner will prevent air bubbles when you press the top sheet down but isn’t necessary. Rounding the corners will prevent snagging on other documents.
If you are encapsulating something you disbound that you want to keep together, make your binding edge extra wide but put the tape next to the document. You therefore have extra plastic for a three-ring hole-punch or whatever method you choose to collect your pages, but the “binding” never touches the document. Remember that your encapsulated document is three times as thick, so its original binding style is probably not an option. If you want to encapsulate something folded, pre-crease your polyester before you position the document in it. If your item is too big, simply use two sheets of plastic and tape all four sides, but create your corner before positioning the document.
One additional advantage to encapsulation is psychological. You have taken visible care of a piece of paper, proving that you value it and therefore making it more likely that the user will also treat it with respect.