Today I encapsulated plan 1399, which shows the design of part of the Librarian’s room. But as it turns out, this plan is "incorrect". The design may have been put in the reject pile, but the plan itself still must be carefully preserved through cleaning and encapsulation. The plans are encapsulated in archival quality polyester film, often called by its Dupont-registered trade name, Mylar. Mylar is a clear, strong film that protects materials from dirt, oil, acids, and other pollutants, and has a life span of hundreds of years.
After a plan has been cleaned, it is ready for encapsulation, and the surface of the work area is wiped off with an absorbent cloth. If the plan is small enough, a scrap from a previous encapsulation may be used. The scraps are kept in the drawer of a dresser in the preservation area.
Otherwise, the large roll of Mylar is retrieved, which is kept under a large cloth to protect it. After bringing it to the work area, the sheet is pulled out to be measured for use. How you position and cut the Mylar for use depends on the size and shape of the plan, and the goal is to avoid wasting any of the material. In this encapsulation, I found that the new roll of Mylar had tape residue, so I was careful not to use the affected areas in the encapsulation.
The plan is laid on the Mylar, and when measuring pieces of Mylar for use, about an inch perimeter is left on all sides of the plan. In this way, two equal pieces of Mylar are cut for use. The Mylar is placed with the inside facing up, with the edges of the material curling upward on the sides, and an anti-static brush is used to remove static. The plan is placed on the Mylar, and a special type of tape is used to frame the document, with about 1/2" between the plan and the tape.
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On one corner, a small amount of space is left between the two pieces of tape, which helps to allow some air in and prevent a microenvironment from developing. The goal is to prevent the sliding of the document in its encasing, while preventing the plan from actually coming into contact with the tape.
The tape is firmly pressed down using a bonefolder, and the edges are lifted slightly, ensuring 
that the tape’s sticky residue is left behind. The second piece of Mylar is treated with the anti-static brush, then placed on top of the plan, making sure the inside is facing down. The tape between the plans is removed, leaving behind the sticky residue, and the top piece of Mylar is carefully laid on top of the plan, ensuring that no air bubbles are left between the pieces. The bonefolder is again used to press the pieces of Mylar together.
The edges of the encapsulated document are cut so that there is about 1/8” of Mylar around the taped edges, and the corners are rounded to prevent sharp edges from harming any other documents. After this process, you have a document that looks nice and is well preserved and protected.
- Laura Pike, Preservation Intern
