Library of Congress NDLP and the Conservation Division Page 1

LIBRARY OF CONGRESS

NATIONAL DIGITAL LIBRARY PROGRAM

and the CONSERVATION DIVISION

CONSERVATION IMPLICATIONS OF DIGITIZATION PROJECTS

Contents

1. Background and Rationale for Collaboration

2. Consultation on Space and Environment

3. Consultation on Equipment/Hardware

4. Training Contractors and NDLP Staff at the Library

5. Conservation Review for Scanning

6. Conservation Treatment

7. Materials at Risk for Loss

8. Conclusions

Appendix I: In-House Course Handout

Part 1: Criteria for Selecting Items for Conservation Treatment before Digital

Scanning

Part 2: Safe Handling of Library Materials – Review of Practices

Part 3: Review Sheet to Select a Scanner for Books

Part 4: Criteria for Selecting Scanning Equipment

Appendix II: Sections in NDLP Request for Proposals relating to Conservation

(to be added – late 1999)

Appendix III: Case Studies (to be added -- late 1999)

9/99
Library of Congress NDLP and the Conservation Division Page 2

1. Background and Rationale for Collaboration

The collaboration of the Library of Congress National Digital Library Program

(NDLP) with the Conservation Division is a fitting partnership because the mission

of the institution highlights both access and preservation. The Conservation

Division has been integrated into the National Digital Library Program since its

beginning in 1995. The NDLP is a program whose primary goal is access, but one

of the key aims is the preservation of the collections, both through converting and

reducing handling of fragile and vulnerable materials and by ensuring that the

process of scanning is safe for the collections. 

The major components of the collaboration have been in the planning and

specification of equipment, training in care and handling of materials, necessary

treatment to stabilize objects, and rehousing design for both image capture and

storage. The result of this collaboration over the last five years can be found in

selected collections whose conditions have been improved for the future. The aims

of the NDLP and of the Conservation Division were considered to be parallel and

to support each other. It has been a successful collaboration and one which

continues to grow and change just as the technology continues to change and as

expertise of the staff evolves.

The National Digital Library selects collections for the American Memory Web site

based on intrinsic historic, visual and educational interest. Other selection criteria

include, determining the need for copyright permissions, privacy or content

concerns, and assessing handling and security risks. Unlike many digitization

projects, difficult to use materials, such as over-sized posters and architectural

drawings, and collections that present a security risk, such as baseball cards, are

included. Over time, we will be able to assess whether digitizing and providing

access to surrogates via digital technologies serve to protect these 'difficult to serve'

collections by reducing wear from improper and excessive handling.1

The NDLP has digitized and continues to digitize manuscripts, photographs, books,

sound recordings, moving image materials, posters, prints, drawings and cartoons,

manuals, pamphlets, sheet music and images of three-dimensional objects. For each

class of materials there is a clear benefit in providing broader and better research

access for multiple users. However, a major program assumption is that digital

surrogates provide efficient access to the content but are not intended to replace

originals which remain secure and protected in appropriate storage.

Whenever there is handling of original collections, there is a need for the application

of conservation knowledge and practice. From the beginning, it was clear that

conservation would be a necessary player in a successful digitization program,

particularly for paper, book and photographic materials. It is widely recognized

that improper handling by staff and users is one of the greatest causes of damage to

library and archival materials. The primary means of assuring appropriate
Library of Congress NDLP and the Conservation Division Page 3

protection and conservation of collections is in the policies regarding their use and

handling. 

The digitization service contracts, described and defined in "requests for proposals"

(RFP's) specify the production requirements and contain many conservation

concerns as part of the contract language. It is essential to have that outline of

expectations in the contract and in any statements that outline work procedures, so

that preservation concerns and their possible attendant costs can be factored into

contractor or vendor proposals as well as into the overall plan of work for a

digitization program.

The Conservation Division/NDLP collaboration begins with a dialogue in the early

stages of planning and communication continues throughout the process of

planning, writing, evaluating, awarding and implementing the NDLP contracts and

subsequent production work. Conservators have the knowledge and experience to

assess the fragility of and risks to the originals so that solutions may be designed

which will help protect the originals through the handling they will receive during

scanning. As a result, through our many interactions with the NDLP staff and the

contractor scanning staff over these past years, we have devised procedures and

practices together, which not only protect, but also expedite scanning.

This collaboration has had an impact on normal conservation services that can be

provided for the Library of Congress collections. In recognition of the time that is

involved in planning, training, reviewing collections and treating items and

collections for digitization, the NDLP funded two and a half staff positions in the

Conservation Division. These staff are responsible for paper, book and

photographic conservation. With this addition of staff hours, we have been able to

provide the necessary collections conservation treatment, consultation and training

support for the NDLP program in a timely fashion.

An added direct benefit of this collaboration for the Library's collections has been

the large number of items that have received stabilization and rehousing in the best

materials that we can now provide for their future preservation. In many cases the

new housings used for the NDLP scanning will provide support for any future

handling that the collection items may receive.
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2. Consultation on Space and Environment

Library security regulations, and the high value of some of the materials scheduled

for scanning, preclude sending most original materials off-site for scanning. 

However, because of the difficulty of moving some of the necessary equipment,

some of the photographic materials were sent off-site. All of the microfilm is being

scanned off-site. Flat paper materials (including maps) and bound volumes from the

special collections divisions are all scanned at various scanning stations in the three

Library buildings on Capitol Hill. The contractors provide staff and all scanning

hardware and software. The Library provides space and facilities support. On-site

scanning is a distinct advantage from the point of view of Conservation as we do

not have to concern ourselves with the conservation requirements for transport of

materials outside of the buildings and security and environmental conditions in

another location.

What was required of the Library was identifying and securing for each scanning

site a large clean area which could accommodate sufficient table space to allow for

the safe handling of materials. We plan for table space six times the size of the

largest object to be scanned in order to have enough free space to allow for the

proper assembling of materials before capture and landing space after capture. This

amount of horizontal space serves to mitigate our concerns over maintaining the

order within collections, keeping housings at hand, and allowing scanner operators

enough room to handle an object a minimum number of times. 

Concern has been expressed about light exposure levels during scanning projects,

while it is actually the heat generated by the equipment and light that is, in fact, the

greater problem. Heat buildup can distort and damage fragile materials, including

leather, parchment, and photographic film and photographic prints. For this reason

careful consideration needs be given to the issue of environment before choosing a

site for the equipment.

Each scanning site must have adequate cooling and air-circulation to counteract

heat that builds up from the equipment, and lights when using overhead capture

devices, as well as for the comfort of the staff. This has been a significant problem,

as normal HVAC settings and airflow in secure Library sites that have been selected

for digitization work stations were not designed for the 5 to15 degrees of heat that

can be generated by equipment and personnel. Secure scanning areas tended to be

small and required retrofitting to provide adequate ventilation or space.

The reduction of the amount of light an item will be exposed to, from both ambient

and scanning equipment light sources, is an important conservation concern. 

Lights, whether they are room lights, stand lights or part of the equipment should

be UV filtered or give minimal UV readings. Current research seems to indicate

that exposure to light and UV energy from scanning is minimal,2 and that light
Library of Congress NDLP and the Conservation Division Page 5

exposure from scanning must be seen in relation to an object's cumulative exposure

to light over its lifetime. Exposure times during scanning are generally short, from

seconds to a few minutes, but may increase if re-scanning is necessary for adequate

image capture. The use of UV filters for all light sources and the use of flat bed

scanners with no UV energy in the light source can minimize concerns about light

exposure levels.

 

3. Consultation on Equipment/Hardware

One of the most practical and basic considerations is to specify project by project,

equipment which can be used for different types of collection materials, particularly

for the paper scanning contract, which includes books (vs. photographic images,

microfilm, motion picture, video, or audio for which there are separate contracts or

service purchases). In most cases, we found that for paper and book items, an

overhead capture device served conservation concerns best. The reason for this is

that nothing touches the originals except the supports, book cradles and the hands

of the scanner operator. 

Scanning hardware has been developed primarily for business and commercial uses

and the cultural heritage sector is a small percentage of the entire digital conversion

field. We examined equipment that was available and which was proposed by

contract bidders, but found many pieces were inappropriate initially. Since that

time, the current NDLP document scanning contractor has assembled a number of

devices which are appropriate for the diverse materials being scanned.

Prior to writing the RFP for paper and book scanning, Conservation and NDLP

staff met with many scanner manufacturers to examine and discuss the effect their

equipment would have on materials. For books, it did not take long to come to a

mutual understanding that inverting them was inappropriate and potentially

damaging for most bound volumes. It was actually much more time-consuming and

difficult for the operators as well. Conservators worked with the current contractor

as well as with other scanning equipment manufacturers by providing advice

regarding appropriate designs for book cradles. In addition, after conservation

review, a small number of books which were determined to be of small size, robust

and flexible, were scanned on a "book-edge" scanner, which did require repeated

inversion of the volume. Disbinding or guillotining text blocks, which the Library

has historically only done when material is no longer serviceable, and thereafter

removed from circulation because it has been converted to another format, was not

a procedure used for NDL collections scanning. 

For unbound materials, scanners with sheet feed devices were examined, but it was

determined that the risk was greater than the attraction of speed. Many old and

worn single sheet items, such as play scripts, and dog-eared single leaf documents,

would be put at great risk by moving them through the transports of such scanners. 
Library of Congress NDLP and the Conservation Division Page 6

For overhead capture devices we found that a fixed light source, rising up at an

angle from the edge of the scanning bed made it difficult to accommodate oversized

materials. Some flatbed scanners, which are designed for oversized originals, have

indented areas and a cover, which can damage originals if they are even slightly

larger than the bed size. On the other hand, after conservation review of both the

originals and the scanner, it was determined that large drum scanners for

architectural documents, that feed the large sheets over a roller could be used to

scan a fairly homogenous architectural drawing collection that was in good

condition, on sturdy support paper, and that had well-adhered, non-friable inks. 

The broad and complex nature of the collections to be scanned and their

conservation concerns requires that conservators evaluate the handling and other

characteristics of contractor equipment by participating in specifying the type of

equipment which can be used by contractors both at the Request for Proposal

(RFP) stage and also after award, each time the contractor decides to bring in

different scanning equipment. For the NDL work, this meant that the contractor

needed to make several types of scanners available for the contract: overhead

digital camera scanners, flatbed scanners and bound volume scanners. Only if the

collection was uniform in every way, was it possible to recommend that only a

single piece of equipment be used to scan that collection. 

Book and paper conservators participated in the evaluation of parts of the

document scanning proposals which were submitted in response to the paper

scanning RFP. After contract award, we turned our attention to the training of

NDL and contractor staff in the handling of the objects, which remains the greatest

variable in the project and therefore the most important area of training. As a part

of the production planning process, NDLP project leaders consult with the NDLP

conservation liaisons and conservation staff for decisions regarding how items are

to be scanned and on which devices. For example, recommendations are made

about the degree to which a bound volume can be opened, based on its condition,

robustness, and type of binding. This could be 180 degrees, which is rare, or 120

degrees, 100 degrees or 90 degrees. For a flat document, the decisions include

whether it can be inverted and scanned on a scanner platen or scanned only by an

overhead device; whether a polyester film enclosure is required to protect an item

during scanning; or, if interior folders should be used for handling during scanning. 

These decisions are incorporated into pre-scanning preparation procedures.
Library of Congress NDLP and the Conservation Division Page 7

4. Training Contractors and NDLP Staff at the Library

The Conservation Division holds training sessions in collections handling both for

the contractor scanner operators, as well as for staff hired by the NDLP. We offer

workshops of one or two hours on a regular and as-needed basis when new

operators or staff are hired. We also provide one-on-one training when necessary

for collections with more special handling requirements. For an outline of the

course and handouts, please see Appendix I.

The first group to be trained were staff who worked for the NDLP in the

conversion group operations and in the special collections areas. Through such

training conservators are able to serve the goals of preservation by guiding project

staff in the assembling, management and handling of the physical objects as they

design production plans. These plans include determining the arrangement and

housing of the collection to be scanned with the goal of minimizing the number of

handlings that an object receives. 

NDLP staff focus on preparing the collections item by item and recording

bibliographic and descriptive information. Many of the collections also require

conservation condition surveying and rehousing. Because the NDLP staff often

were handling each item, to identify and record descriptive and bibliographic

information, they also performed much of the conservation condition surveying and

the rehousing required. 

Each collection is initially surveyed by a conservator who prepares a 'Conservation

Work Sheet' tailored to the needs of the collection. The NDLP staff is trained to

use the form to identify the items needing treatment. They are also trained to

rehouse the collections with materials which are specified and purchased through

the Conservation Division. A typical rehousing involves placing single leaf items in

individual acid-free folders. During this item review process, items in need of

conservation treatment are sent in batches to the Conservation Division for

treatment prior to scanning.

Conservators also train the operators who scan the collections, as is required in the

contract. The contract requires staff to exercise utmost care in handling, even if

that increases the time. Lines of communication between the NDLP staff, scanner

operators and Conservation are opened through the training and the operators are

encouraged to consult with conservators throughout the scanning process. 

It has been of the utmost importance to ensure that the collections are not harmed

in any way during processing and conversion. We found for example that the

human hand is the most sensitive way of holding pages open and books in place --

far more sensitive than robotic arms and strapping devices, etc. Scan times are in

fact short enough that this has worked well. The operators for this project have

been very sensitive to handling collections materials and their skills and dexterity
Library of Congress NDLP and the Conservation Division Page 8

continue to improve as they handle and scan a greater number and variety of

materials through the course of the program.

5. Conservation Review for Scanning

The initial conservation review occurs most often before the final selection of a

collection for scanning. Based on the types of items (book, paper or photo) the

appropriate conservators review a sampling of materials. Generally, the problems

that appear in each collection are quite distinct and specific to the type of material

being scanned. Often the housing of documents and photographs needs to be

changed to ease handling for the scanner operators and also to provide more

protection for the materials. See Appendix I, Part 3, for the "Review Sheet to

Select a Scanner for Books."

We prepare a Conservation Work sheet for each item in a collection that allows the

NDLP staff to separate out items that need conservation treatment before scanning. 

For a description of the typical criteria used for determining whether an item needs

conservation work, please see Appendix I, Part 1. Typically, the databases used for

production also include this information. Based on the amount of conservation

treatment required, the production work-flow is designed and the collection is

scheduled for scanning.

6. Conservation Treatment

The major criterion determining the level of treatment for the NDLP is to ensure

that the textual or visual information can be accurately captured by the scanner

without compromising the item. There is neither time nor funds available to treat

each item fully, following standard Library of Congress conservation practices. The

goal for this program is generally the minimum treatment that provides the requisite

clarity and security. The concern for aesthetic presentation is secondary, though

the aims are not mutually exclusive. The stabilization and treatment of collections

for digitization is only different in that clarity and legibility of information is so

critical.

We know that each item will need to be handled by the scanner operators, perhaps

repeatedly, if re-scanning is required, so for flat items each item must have

individual support. Anything sent to the scanner in encapsulation, is required to

remain in the encapsulation throughout scanning. This seems to work better with

overhead capture than with flatbed scanners. Because of the appearance of

Newton-like rings in the digital images when polyester film is used with flatbed

scanners, we put as few items as possible in polyester film. Instead, in these cases

we have had to rely on the sensitivity of trained operators at the scanning device. 
Library of Congress NDLP and the Conservation Division Page 9

Treatment work that is performed is necessary and critical to the stability of the

materials. About one-half of the treatments could be considered minimal

stabilization. Examples include: humidifying and flattening foldouts in books;

ensuring that no text is obscured by creases; mending tears selectively; dry-cleaning

where necessary; mending weak and torn folds where handling might cause further

damage; and placing very thin and iron-gall ink damaged sheets or mold damaged

materials into polyester film encapsulations. 

Full treatments have been carried out on some pamphlets, music scores, and small

bound items, such as manuals, with brittle paper or covers, which require complete

rebinding in order to be scanned safely. Flat paper items receive full treatment

when the minimum acceptable treatment will take the same amount of time. 

Photographs mounted on brittle and curved boards also require more treatment,

both for handling and aesthetic reasons. The normal treatment is stabilization of

boards by mending breaks, filling losses and providing additional support for the

boards. Mounted photographs and most books are scanned with an overhead

camera to minimize risk to their fragile structures.

It has not been necessary during this program to refuse scanning for any item or

class of materials because of the close collaboration and trust that has developed

between the curatorial, conservation and NDLP staff who handled the original

materials. We do attempt to complete treatment for enough material in advance so

as not to impede scanning. However, we do not allow scheduling to compromise

the conservation treatment work. With proper planning, treatment and production

can move forward at a complementary and efficient pace. Different collections

require different levels and amounts of time in treatment. A few collections have

required post-scanning treatment, to place the items in more appropriate long-term

housings. A constant challenge has been scheduling to meet the goals for each

scanning contract with a large number of objects from broad collections with

varying conservation needs.

7. Materials at Risk for Loss

For the Library of Congress, digitization continues to be explored as a preservation

strategy for materials that must be reformatted or converted. Examples of this

include particular collections that are in a severe state of deterioration, where the

digitization process may in fact capture the information before it disappears, and

where money to restore or reformat by traditional means is not available. 

One example is a pilot project for severely channeled and buckled cellulose

diacetate black and white negatives which became more readable in the digital form

because the distortion was flattened out in the converted image, and much of the

information in the channel was captured. In this case it is possible that the scanned

images could be used to create a new hard-copy image surrogate which would
Library of Congress NDLP and the Conservation Division Page 10

1..

 The use of original materials in the Library of Congress reading rooms is not tracked

uniformly by collection and item, so future assessment will be based on subjective evaluation of

a reduced need for remedial treatment to the originals for those collections accessible via the

web.

2..

 Tim Vitale, “Light Levels Used in Modern Flatbed Scanners.” In RLG Diginews 2, no.

5(October 15, 1998), available online at http://www.rlg.org.

3..

 Mary T. Baker, “Lifetime predictions for polyurethane-based recording media binders:

Determination of the shelf-life of videotape collections.” In Resins: Ancient and Modern, ed.

M. M. Wright and J. H. Townsend. (Edinburgh: The Scottish Society for Conservation and

Restoration, 1995), pp. 106-110.

preserve the informational content. The original materials could then be moved

immediately to cold storage for long term preservation. 

Another specialized case is magnetic media in both sound and video recordings. 

The original substrate of magnetic tape has an extremely short life of an estimated

30 to 50 years,3 and magnetic tape onto which one can convert is possibly an

"endangered species" as the industry moves away from producing the various

magnetic tape formats. This area is currently being explored by the Motion Picture,

Broadcast and Recorded Sound Division of the Library of Congress.

8. Conclusions

Conservation requirements were integrated into the specifications for contracts,

evaluation of equipment and processes, and production work flow of the National

Digital Library Program. Many materials received treatment and rehousing which

will extend the life of the original. Most importantly, the goal of causing little or no

harm to the collections during conversion continues to be met in the NDL program. 

As we continue to explore the use of new technologies and new approaches in

preservation, we will continue to collaborate and use approaches and

methodologies developed in conservation to inform the decisions that will need to

be made in future digital projects.

The following people worked on the NDLP/Conservation team. From the NDL

program: Carl Fleischhauer, Tamara Swora-Gober, Nancy Eichacker, Phil Michel,

and Jan Lancaster. From the Conservation Division: Alan Haley, Yasmeen Khan,

Andrew Robb, Ann Seibert, and Mary Wootton.