Preservation Guidelines for Digitizing Library Materials
In keeping with the goals of preservation and access at the Library of Congress, original collection materials are digitized for a variety of reasons, including for online exhibitions and for the online catalog. The first step in the process of digitizing Library collection materials is to review the following considerations:
- What is the purpose of the digitizing project?
- Who will be the users of the digital surrogates?
- How will the digital surrogates be presented?
- What will be the effect on the original collection item of making the digital surrogate?
- How will the digital files be accessed and stored?
Custodians of library collections need to address these questions before a digitization project is implemented. After these questions are answered, Preservation and Information Technology Specialists assess the project requirements and create project workflows. This document defines the guidelines offered by Preservation in the implementation of a digitization project at the Library.
Preservation Assessment of Project Requirements
Preservation assessment of project requirements includes the following considerations:
- Is the condition of the collection such that the item or items can be handled safely throughout the project workflow?
- Can the risk of damage to the collection be minimized with appropriate scanning equipment and workspace?
- Can the risk of damage to the collection be minimized by training the scanning staff?
- How much treatment is required to stabilize the collection for the project workflow?
- Can treatment of the collection be reduced by providing temporary supports and housings or by providing handling by a conservator?
- What is the most cost effective scenario for timely digitization without damage to the collection?
Preservation Assessment of Item Condition
Preservation assessment of collection items selected for digitizing identifies the following condition problems:
- Text obscured by folds or creases
- Paper or photographs that are cockled and need to be flattened
- Tears in paper or text area that are longer than ¼”
- Books with loose joints, detached spines, or boards
- Restricted bindings that open less than 90 degrees
- Acidic or otherwise damaging housing that needs to be replaced
- Difficult formats, such as scrolls, accordion books, palm leaves, panoramas, or oversized items
Preservation Review of Scanning Equipment
Preservation has worked with digital conversion experts to select and adapt the scanning equipment used for digitizing Library collections. When Library collections are digitized by contractors, Preservation reviews and approves the equipment, always with consideration to the format and character of the items being digitized to minimize the risk of damage to collections.
Preservation requirements for digitizing contractors include:
- Form feed equipment is not acceptable for scanning fragile, high-value, fine art, or special or archival collection materials including drawings, graphic prints, manuscripts, newsprint, photographs;and equivalent materials.
- Scanning equipment must feature controls to limit light and heat exposure to the items being scanned.
- Scanning equipment must be properly sized to accommodate collection materials without causing damage.
- Oversized materials, including books that have foldouts, must be scanned using equipment that features a scanning bed that is as large or larger than the object to be scanned.
- Scanning equipment must be adjustable to the height of the collection item to accommodate books that need cradle support.
Preservation Recommendations for Workspace
Basic guidelines for the workspace and the worker are listed here:
- Work on a clean, roomy, and tidy work table.
- Wash and dry hands before working with Library materials.
- Wear gloves when handling photographs.
- Use only pencils near Library materials. No ink or felt tip pens or markers, colored pencils, crayons, etc.
- Keep work spaces free of food and drink.
- Close books and cover collection items when leaving work area.
- Remove and replace Library materials in their containers carefully.
Preservation Requirements for Training
Digitization technicians at the Library of Congress are trained by Preservation specialists in the basics of careful handling of Library materials and in how to safely support objects on the scanning equipment. Preservation staff members teach with non-collection samples of bound materials, flat documents, graphic prints, manuscripts, atlases, photographs, and photograph albums to demonstrate the damage that can occur to fragile Library materials during scanning.
Basic guidelines for careful handling of bound Library materials are:
- Don’t apply pressure to books in order to flatten them for image capture. Such pressure can break the spine or loosen or break off brittle pages in a book.
- Place books with weak joints or restricted openings in a book cradle (blocks or rolls of polyethylene foam) during image capture.
- Handle brittle paper with extreme care. Artwork, documents, manuscripts, prints, photographs, and their mounts can also be brittle.
- Don’t remove foldouts from books. Carefully open the foldout onto a support during image capture.
- Don’t place glass or Plexiglas® on top of artwork, documents, manuscripts, prints, photographs, with or without mounts, or other Library materials to flatten for image capture. This can cause media to crack or to detach from the item.
Preservation Recommendations for Housing:
The digitizing workflow allows for the following to take place:
- Removing and replacing acidic or otherwise damaging housings
- Adding new housing (e.g., boxes, folders, mats, or other archival containers) to protect items during transport to and storage at the worksite
Preservation Stabilizing Treatment
Some collection items need minimal conservation treatment by trained conservators before they can be safely transported, handled, and digitized. “Stabilization” is minimal conservation treatment performed by conservators such as:
- Opening of folds or creases that obscure text or images
- Relaxing cockled or creased paper or photographs
- Mending tears
- Repairing loose book joints
- Re-attaching loose or detached spine pieces or boards
Materials that May Be Excluded from the Digitization Process
Some items require more involved and expensive repair, or are so fragile that they cannot be easily stabilized. For these items, Preservation specialists must discuss treatment options with the curator of the collection. Some examples of materials that may be excluded from digitization are:
- Paper that is acidic, fragile, brittle, torn, missing pieces, sticky or stuck to something.
- Paper documents with three-dimensional objects (e.g., medals, seals, ribbons) attached.
- Paper with iron gall ink that has eaten into the page.
- Loose, flaking or friable media such as crayon, charcoal, chalk, or soft pencil.
- Books with severe leather deterioration (i.e., red rot) or missing pages.
- Letter copy books with very thin and acidic paper, such as carbon copy correspondence and some tracing paper drawings and plans.
- Photographs that are separating from the mount or support.
- Photographs that are curled, bent, creased, folded, wrinkled, cockled or cracked.
- Photographs and their mounts which are acidic, fragile, brittle, torn, missing pieces, sticky or stuck to one another.
- Deteriorated cellulose nitrate or acetate film negatives and positives.
- Scrolls or other non-traditional textual or image formats.