16 Safeguarding the Stacks: A Preservation Lesson Plan for Those Working with Physical Archival Materials

In the cultural heritage field, preservation is an umbrella term for all policies, actions, and programs directed at protecting collections of materials from physical deterioration and loss of content. Conservation encompasses treatments performed on individual items to restore materials to usable form or slow physical deterioration. Overall, preservation programs reach beyond item-level protection and help maintain entire collections through preventative actions such as environmental monitoring, object handling training, proper collection storage, and the selection of archival housing supplies. Preservation activities help minimize the potential of physical damage to archival materials.

Everyone working with archival collections plays an active role in the preservation and safeguarding of materials through careful handling, storage decision-making, and the implementation of monitoring programs. This lesson plan provides an overview of key preservation concepts along with practical instruction on the preventative and long-term care of primary source and archival materials. Information in the lesson will increase awareness of preservation needs, promote the role of collection care in the long-term stewardship of archival items, and empower archivists to take active steps to promote care for collection materials.

Environmental Monitoring Programs

Ben Franklin’s adage “an ounce of prevention is worth a pound of cure” resonates in the preservation field. With cultural heritage collections, it is essential to be aware of various environmental conditions that impact long-term collection care and address problems as soon as possible. Establishing formal programs and activities to monitor temperature, relative humidity, light exposure, biological activity, air quality, and water threats, and to inspect an archival facility’s structural integrity, helps archivists identify problems early and promotes optimal environments for collections. Additionally, archivists can minimize potential damage to collection materials by creating disaster preparedness and response plans that address emergencies such as building fires and flooding, along with plans that outline strategies to minimize the potential impact on collections of exterior regional dangers such as earthquakes, tornados, tsunamis, and volcanic eruptions.

Temperature and Relative Humidity Monitoring

Ambient temperature and relative humidity levels work synergistically and, when controlled, can help promote the long-term preservation of cultural heritage materials. In general, archival storage rooms are kept slightly cooler than general workspaces (60–68°F/15–20°C) and humidified at set points appropriate for various materials (paper-based collections 45% +/-5, photographic materials 35–45% +/-5). When conditions are too warm and moist, mold can bloom and harm collections. When conditions are too arid, materials can buckle, split, and warp. Furthermore, swift changes in temperature and humidity levels are harmful. In the event of an HVAC (heating, ventilation, air conditioning) system failure, it is best to initiate incremental corrective changes slowly over a 48- to 72-hour period rather than immediately returning the building system to target set points. Moreover, seasonally, buildings will see slow changes within target set point ranges. Generally, seasonal flux is not pronounced.

As a preservation strategy, archivists measure temperature and humidity levels on an ongoing basis throughout storage rooms, workspaces, and exhibit areas to understand a building’s baseline environment, to identify troublesome areas, and to recognize when HVAC systems are encountering mechanical problems. Temperature and humidity levels can be monitored electronically through a building’s automation system (BAS), digital dataloggers, stationary analog hygrothermographs, and spot-checked with handheld testing instruments. Readings should be taken continually and should be reviewed at regular intervals.

Light Monitoring

Paper-based cultural heritage materials, especially those that are hand-colored or produced on poor-quality acidic paper, as well as photographic materials, are highly susceptible to light damage. Physical damage from light exposure results in fading and embrittlement, and the damage is cumulative and irreversible. Exposure to ultraviolet radiation from natural sunlight and some artificial light sources, such as fluorescent bulbs, damages materials. The duration of exposure and level of light intensity amplifies damage.

Materials stored inside housing containers, such as folders and boxes, are shielded from light exposure and the impacts of direct lighting. Ideally, it is best to store, exhibit, and use collection materials in spaces without windows and illuminated by non-UV light sources (e.g., LEDs or incandescent bulbs). In spaces with natural light sources, archivists can apply protective UV-filtering films to windows. Similarly, archivists can add filtering films over some UV light sources, such as fluorescent tube-style bulbs. UV-filtering films generally have lifespans of up to ten years. Additionally, turning off unneeded lights and using motion-activated lights in collection spaces helps minimize light exposure. Controlled, dimmable lighting is especially helpful in exhibitions, as is limiting the length of exhibition time to shows under four months.

Light intensity and UV radiation can be measured with handheld light meters. Archivists can deploy light meter dataloggers and analog blue scale fabric swatches to measure and monitor light exposure and UV radiation in collection storage areas and in exhibition areas on an ongoing basis.

Monitoring Biological Agents

Biological agents, such as insects, vermin, and mold, can harm collection materials. Keeping archive facilities clean, without plants, and free of food, along with maintaining controlled relative humidity and temperature levels, deters biological activity and minimizes risks to collections. Additionally, correcting structural building issues such as repairing leaky pipes and caulking gaps around windows and doors can prevent insect activity in collection spaces. Overall, monitoring for biological activity is an essential ongoing preservation activity. By identifying small problems, archivists can prevent pest damage without needing to react with chemical deterrents that can off-gas and harm collections and people.

Integrated pest management (IPM) programs are tailored to meet the needs of each facility and address preventative, reactive, and monitoring strategies. A common approach to IPM involves employing sticky traps to monitor insect activity in collection rooms. Using a map of storage spaces, archivists set traps throughout a space, placing them in a grid configuration. After three to four months for routine monitoring, or sooner if there is a suspected infestation, archivists collect the traps and identify the type and number of insects. It may be helpful to enlist the help of an entomologist at a natural history museum or university to identify insects. After insect traps are examined, archivists can study the number, location, and types of pests in the archival areas. If there are signs of problems, archivists can tighten the area of inspection and employ additional traps during the subsequent testing cycle. If there are no signs of problems in an area, archivists adjust trap locations and rotate trap sites throughout the space to continue monitoring the space.

After each test cycle, archivists map and log findings and continually review sites of past pest activity. Once archivists know the types of common pests, they can address issues and begin eliminating or minimizing the populations. Continuous studies will help archivists understand “normal” population sizes and cycles. Over time, archivists will better understand warning signs and head off infestations as situations occur. In addition to helping protect collection materials from insect damage, pest monitoring helps archivists identify areas that may need cleaning, have building issues to correct, or show signs of a budding infestation.

Air Quality Monitoring

Air pollutants may harm collection materials and speed up deterioration rates. Ideally, cultural heritage organizations should monitor air quality and filter pollutants such as acids, aldehydes, sulfides, and ozone. These contaminants threaten the long-term care of papers, metals, pigments, plastics, and AV materials in collections.

At the macro level, archivists can work with building engineers to employ high-quality air filters that filter airborne pollutants. Additionally, archivists can ask engineers not to use additives in HVAC systems that service collection areas to avoid introducing chemicals into the environment.

Metal artifacts prone to tarnishing may be proactively wrapped in protective barrier cloths, such as Pacific Silvercloth, or housed with sachets of pollution scavenger agents, such as Carbusorb, to minimize damage from pollutants and periodically monitored for changes.

Monitoring Water Sources

Water can damage archival items by direct contact and water leaks in archival spaces can contribute to mold growth, pest infestation, and structural damage to the facility. If archivists are aware of areas vulnerable to leaks, they can monitor those areas for signs of problems and address issues in an efficient manner to minimize potential water damage.

Archivists should audit spaces to identify areas vulnerable to water leaks. During an audit, archivists can identify and map the location of pipes in or adjacent to collection spaces. Additionally, archivists should be aware of areas below grade, along exterior walls, or directly below roofs that are vulnerable to water damage.

All collection spaces should be monitored for water. Archivists can use the map of vulnerable areas to help them position water alarms. Leak detecting equipment can be battery operated or Wi-Fi enabled and help alert archivists of water on floors, under pipes, and near exterior walls and roofs.

Structural Monitoring

Building infrastructure, fixtures, and materials can fail over time. Identifying weakening components before they break allows archivists to proactively work toward preventing issues that impact collection preservation and safety. Archivists can schedule routine structural inspections to help spot potential areas of concern.

Archivists can create a checklist of vulnerable or problematic spaces to inspect inside, adjacent to, and outside the building. While inspecting, archivists should look for cracks, stains, broken fixtures, tight doors, damaged pipes, loose cables, signs of forced entry, failing shelving, signs of mold/pests, and any other signs of trouble. During inspections, archivists should photograph, measure, and document problems, and work with building engineers to correct and address problems. It is helpful for archivists to keep a log of inspections and follow up actions that they can consult as they track issues.

Disaster Planning

Emergency preparedness and disaster response plans help archivists minimize collection losses and navigate crisis situations. Plans can cover prevention and response strategies for acts of vandalism, theft, fire, flood, and extended periods of service interruption, as well as procedures relating to natural disasters such as earthquakes, tornados, tsunamis, wildfires, and volcanic eruptions.

Emergency preparedness plans identify the types of risk an institution may likely face and help archivists proactively outline mitigation strategies to minimize damage. Plans also define roles for responders, outline staff training needs, list salvage supplies to keep on hand, and gather contact information for key staff, remediation vendors, and regional cultural heritage agencies that could assist during a crisis.

Disaster response plans articulate collection salvage priorities and outline triage responses to guide efforts. Plans instruct archivists on how to respond to collection damage by format type in hopes that swift and appropriate reactions will minimize loss and damage to collection materials and the facility.

Handling

Archivists can prevent accidental damage and minimize the cumulative impact of handling collection materials by following object handling best practices. Here are some tips to keep in mind.

General

• Do not be anxious when working with cultural heritage materials. Relax and work with confidence.
• Work at a cautious, steady pace. No need to race.
• Give your work your full attention, be mindful.
• Know where you will move things before your start, have a cart or surface ready.
• Handle materials as little as possible, and only as needed.

Prevent the Preventable

• Maintain a clutter-free workspace to help prevent accidents.
• Keep furniture and equipment in good working order.
• Use sturdy ladders and foot stools to reach shelves.
• Avoid using pens, markers, stickers, adhesive notes, and general office supplies.
• Keep food, beverages, smoking, and plants away from collections and processing areas.
• Watch for catch hazards like ties, scarves, belt loops, drapey sleeves, jewelry.

Hands in Handling

• Clean hands, wash as needed.
• Skip hand lotion and fingernail polish.
• Wear gloves when handling photographic materials and metal objects.

Heavy and Oversized Materials

• Do not overextend yourself, ask for help with heavy, oversized, and unusually shaped materials.
• When in doubt, set materials aside and seek help to move.

Monitoring Conditions

• Look for weak spots and trouble areas before picking something up.
• Monitor the condition of materials as you work.
• If condition changes/worsens, stop working with materials and seek help and reassess.

Transporting Materials

• Do not overload a cart, make multiple trips.
• Line materials up in the center of the cart rather than at the edge.
• Drive slowly, be alert.

Storage and Housing

The storage and housing of archival collection materials directly contributes to long-term preservation goals. Housing creates micro-climates that protect materials from light and pollutants, mitigates changes in temperature and humidity levels, provides physical protection from accidental contact, helps protect an item’s physical shape, and provides areas for labeling and identification.

Archival storage and housing decisions are based on several factors:

• Physical needs of an individual piece
• Phase in the processing life cycle when decisions are being made
• Space available for storage
• Funds available for housing materials for a project
• Efficiency and uniformity

Housing decisions should aim to offer general physical protection that promotes long-term care and prevents harm such as breakage and warping. Select items of historical or curatorial importance may warrant more robust storage solutions. Overall, storage housing decision-making is a bit of a balancing act. This tutorial covers many situations archivists commonly encounter.

General

• Avoid storing materials in attics, in basements, on floors, against exterior walls, or under pipes.
• Do not store materials in direct pathways of vents and be sure not to block vents.
• Avoid long-term storage in sunlight or under florescent lighting.
• Store heavy and cumbersome materials in easy to reach places.
• If stacking items, keep stacks short, place the largest materials on the bottom, and the smallest on top. Some materials cannot be stacked.

Uniformity

Neatness, conformity, and consistency promotes less frequent and safer handling.

• Store like things together, store like sizes together.
• Orient materials and enclosure openings consistently.
• Mark folders legibly and in consistent locations to promote ease of use and minimize handling.

Notes on Archival Storage Boxes

• Only use archival-quality storage materials.
• Use enclosures that are good fits for materials inside.
• Do not use damaged storage containers.
• Do not overstuff folders and boxes.
• Use spacers inside boxes to fill gaps and support material.
• Remove rubber bands and paperclips, replace with archival fasteners such as Plastiklips.
• Use both hands to move storage boxes.

Supplies

Archival supplies may look like traditional office supplies, but they are specially designed to meet the long-term preservation needs of cultural heritage collection items. Archival-quality supplies will not deteriorate and harm materials. These supplies are sold through specialized vendors who understand the needs and aims of cultural heritage organizations.

Archival supplies often contain chemical alkaline buffering agents that counteract the acidic nature of paper. This chemical treatment helps extend the life of paper items but can harm photographic materials. With photographic materials, archivists select non-buffered folders and envelopes to avoid unwanted chemical reactions.

Helpful Terminology for Selecting Archival Supplies

• Acid-free: materials with a pH value of 7.0
• Alkaline or buffered: paper products with a pH value of 8.5 or greater where a substance, frequently magnesium salt or calcium, is added to help neutralize acids and help reduce paper deterioration; buffered papers are not recommended for use with photographic materials.
• Lignin-free: paper products, such as 100% linens and cottons, which naturally do not contain lignin, or products that have had lignin cellulose removed from the wood pulp during manufacturing; lignin-free papers are long lasting.
• Non-buffered: paper products that do not contain a buffering agent; non-buffered archival papers are suitable for use with photographic materials.
• Photographic Activity Test: commonly known as the PAT, international product standard ISO 18916, it assesses possible chemical reactions between photographs and other materials in prolonged physical contact and guides selection of materials better suited for long-term storage of photographic materials.

Storage Decisions by Format

During archival processing work, archivists most frequently encounter paper-based materials, such as loose sheets of paper, books, maps, and certificates, but also process photographic materials, audio-visual resources, and various types of artwork. These materials benefit greatly from archival supplies and supportive housing. The following guide lists storage and housing advice for a range of items archivists commonly process.

Art

Artifacts (sculptures, banners, trophies, and a variety of 3D items)

• Store inside print boxes, divided trays, artifact boxes (pad inside of boxes with spacers or acid-free tissue to immobilize artifacts as necessary).
• Store large items in artifact cabinets or on fixed shelving.

Framed Artwork

• Store on dedicated art rack shelving.
• Store face up and flat inside print box (for multiple items, store with sheets of archival corrugated board between pieces).
• Store upright, oriented frame to frame or back-to-back to prevent damage from hanging hardware.
• It may be appropriate to remove the framing materials if they are in disrepair, bulky, and/or do not add value to the piece. Remove and discard frame and backing materials, then store inside archival folder.

Audio Visual Materials

Audio Cylinders (includes wax and plastic cylinders)

• Store upright on ends like a drinking glass, do not store on grooved surfaces.
• Store inside original container or inside archival audio cylinder storage container.
• Handle at ends, do not touch grooves.
• Wear gloves when handling.

Wire Recordings

• Store upright, not stacked.
• Store inside original container or inside archival audio cylinder storage container.

Audio Discs (this includes a variety of diameters, play speeds, and base materials such as shellac, lacquer, and vinyl)

• Store vertically, supported (either in audio box or on shelving).
• Handle at edges and at hub, avoid touching grooves.
• Sleeve disc in clear anti-static archival sleeves.

Metal Discs

• Store flat in short stacks (under 6”).
• Store in paper archival sleeves as needed.
• Handle at edges and at hub, avoid touching grooves.
• Sleeve disc in clear anti-static archival sleeves.

Open Reel Magnetic Audio Tapes

• Gently wind if tape is loose, wear gloves.
• Store upright.
• Store in original box or inside archival audio box.
• Handle at center hub and outer rim, avoid touching tape.
• Keep at least a foot away from electrical outlets, electric motors, and magnetic fields to prevent accidental erasure.
• Before storage, play entire tape at regular speed.
• Play tape through at regular speed every three to five years to help keep tape supple.
• Store open reel tapes in the fully fast forwarded (tails out) position to minimize voice ghosting.

Cassette Tapes (including micro cassettes, 8-track tapes, and digital audio tape cassettes)

• Store upright.
• If present, store in original case.
• Remove overplay tabs to prevent accidental erasure.
• Handle outer shell and do not touch magnetic tape.
• Keep at least a foot away from electrical outlets, electric motors, and magnetic fields to prevent accidental erasure.
• Before storage, play entire tape at regular speed.
• Play tape through at regular speed every three to five years to help keep tapes supple.

Video Cassettes (including VHS, Beta, U-Matic)

• Keep in original box.
• Store upright like a book.
• Keep at least a foot away from electrical outlets, electric motors, and magnetic fields to prevent accidental erasure.
• Remove or disengage overplay tabs to prevent accidental erasure.
• Before storage, play entire tape through at regular speed.
• Play tape through at regular speed every three to five years to help keep tape supple.

Optical Media Discs (including CD, Laserdisc, DVD, Blu-ray)

• Handle disc by the outer edge or center hole and hub.
• Label container or/and disc hub using archival marking pen.
• Store upright in original case or archival sleeve or case.
• Gently clean (wipe in straight line away from center hole towards edge) using lint-free lens cloth.

Motion Picture Film (including gauges 8 mm, Super 8, 16 mm, 35 mm; base materials include nitrate, acetate, and polyester)

• Store flat in short stacks (under 12”) of like sized cans.
• Store film in vented archival plastic film containers.
• Label film using archival paper leader strips and wrap around outer edge of film.
• With film emitting vinegar odors, use A-D acetate film testing strips and assess for reformatting needs. Store decomposing (vinegar syndrome) materials separately.
• Ideally, it is best to transfer film from reels onto cores for storage.
• When film is wound onto cores, wind evenly and not too tight, wind emulsion side out.
• When film is transferred to cores, it is best to clean film and attach polyester film head and tail leaders using tape splices.
• Isolate and reformat nitrate film. Nitrate film is unstable and poses a fire hazard.

Bound Materials

Books

• Store books upright, oversized books are best stored flat.
• If bound material is stored inside boxes, be sure it is placed spine down rather than fore-edge down.
• Support upright books with bookends.

Comic Books

• Store upright in folders (or spine down).
• Store in archival comic book storage box.
• Store individual items inside archival polyester sleeves with archival backing board.
• Use spacers inside partially full boxes.

Scrapbooks

• Do not stack scrapbooks. Many are made of composite materials and weight can easily damage items inside the album.
• Store inside archival print box, store upright or flat depending upon size and condition.

Paper Items

Loose Papers

• Folder items using buffered, lignin-free archival supplies.
• Orient in one direction within folder.
• Do not overfill folders.
• Keep folder sizes smaller for brittle and highly fragile items.
• Score bottom of folder to width of contents.
• Support folders within box.
• Encapsulate in archival polyester sleeve (such as Mylar or Melinex) if very fragile, needs additional support, very valuable, or will be handled frequently.
• Replace non-archival clips and staples.

Brittle or fading papers that need preservation duplication (thermal fax paper, brittle news clippings, dittos, mimeographs, highly brittle acidic paper that has turned brown, etc.)

• Create preservation photocopy on acid-free bond paper.
• Encapsulate original in archival polyester sleeve (such as Mylar or Melinex) if brittle.

Photographic Print Materials

Select neutral and unbuffered housing materials for photographic materials.

Glass Plate Negatives and Lantern Slides

• Insert into un-buffered four flap sleeves.
• Store vertically in slotted slide cabinet drawer, slide box, or vertically in a tightly packed card box.
• For broken/cracked plates, insert in un-buffered four flap sleeves and sandwich between stiff acid free corrugated boards.

Film Negatives

• Handle with gloves, touch at edges.
• House inside un-buffered/neutral folders or un-buffered/neutral envelopes.
• Store supported inside processing or in print boxes with other collection materials.
• House inside archival paper negative holders (non-buffered/neutral) or clear archival polyester negative sheets.
• Store upright boxed in negative box, fully supported, or flat in an archival three-ring album.

Slides

• Avoid touching film, handle frame.
• Store upright inside slide carton or in clear archival polyester slide album sheets.

Photographic Prints

• Use un-buffered/neutral archival supplies.
• Store vertically in white folders or white envelopes.
• Store flat in short stacks inside print box.
• Interleave individual photographs with glassine and insert into un-buffered/neutral folder.
• Store envelopes inside archival print boxes with lids.
• Mat with archival non-buffered/neutral mat board, acid-free tissue paper slip sheet between print and matting, stored flat inside a Solander print box.

Blueprints

• Use un-buffered/neutral archival supplies.
• Flatten material as necessary.
• Store flat in flat file or print box.

Microfilm

• Store microfilm wound.
• Remove rubber bands.
• Store individual microfilm vertically inside microfilm boxes or drawers.

Microfiche

• Store inside un-buffered archival sleeve or envelope with emulsion side away from the interior enclosure edge.
• Store vertically inside archival storage boxes.
• Store inside archival microfiche cartons or drawers.

Learning Exercises

The following exercises incorporate preservation concepts and principles discussed in this lesson plan. The exercises highlight the considerations and assessments collection care staff undertake to preserve cultural heritage collections in archives and libraries. These exercises can be undertaken independently or in small groups.

Bibliography

American Institute for Conservation. “Emergency Response and Salvage Mobile App.” https://www.culturalheritage.org/resources/emergencies/emergency-response-app, archived July 16, 2023, at https://web.archive.org/web/20230716121247/https://www.culturalheritage.org/resources/emergencies/disaster-response-recovery/ers-app.

Cloonan, Michele Valerie. Preserving Our Heritage: Perspectives from Antiquity to the Digital Age. Chicago: ALA Neal-Schuman, 2015.

Eckstein, Amanda W. “Biological Infestations.” In National Park Service, Museum Handbook Part 1. 2014. https://www.nps.gov/museum/publications/MHI/CHAP5.pdf, archived March 14, 2023, at https://web.archive.org/web/20230314214041/https://www.nps.gov/museum/publications/MHI/CHAP5.pdf.

Forde, Helen, and Jonathan Rhys-Lewis. Preserving Archives, 2^nd ed. London: Facet, 2013.

Gorman, G. E., and Sydney J. Shep, eds. Preservation Management: For Libraries, Archives and Museums. London: Facet, 2018.

Gracy, Karen F. Film Preservation: Competing Definitions of Value, Use, and Practice. Chicago: Society of American Archivists, 2007.

Joffrion, Elizabeth, and Michele V. Cloonan. Advancing Preservation for Archives and Manuscripts. Chicago: Society of American Archivists, 2020.

Lavender, Kenneth. Book Repair: A How-to-Do-It Manual, 2^nd ed. New York: ALA Neal-Schuman, 2011.

Northeast Document Conservation Center. “3.10 Emergency Salvage of Moldy Books and Paper.” In Preservation Leaflets. 2015. https://www.nedcc.org/free-resources/preservation-leaflets/3.-emergency-management/3.10-integrated-pest-management, archived February 5, 2023, at https://web.archive.org/web/20230205082153/https://www.nedcc.org/free-resources/preservation-leaflets/3.-emergency-management/3.10-integrated-pest-management.

Pacifico, Michele F., and Thomas P. Wilsted. Archival and Special Collections Facilities: Guidelines. Chicago: Society of American Archivists, 2009.

Ritzenthaler, Mary Lynn. Preserving Archives and Manuscripts, 2^nd ed. Chicago: Society of American Archivists, 2010.

Ritzenthaler, Mary Lynn, and Diane Vogt-O’Connor. Photographs: Archival Care and Management. Society of American Archivists, 2006.

Saunders, David. Museum Lighting: A Guide for Conservators and Curators. Los Angeles: The Getty Conservation Institute, 2020.