Choosing Materials for Storage, Exhibition & Transport

This page provides guidance on sustainable preservation and collection care activities.

Wiki Contributors: Rachael Perkins Arenstein, Mary Coughlin, Lisa Elkin, Lisa Goldberg, Jennifer K. Herrmann, Rebecca Kaczkowski, Julia Sybalsky, Margalit Schindler, Elena Torok, Joelle Wickens

Find info on materials for collection use

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Why is the Choice of Materials Important?

The materials we use to store, exhibit, and transport cultural heritage collections can have a profound impact on the preservation of these collections. Physical or working properties (rigidity, adhesive strength, cushioning capacity, color, size, machineability, etc.) may be critical in the selection of potential products that can meet the needs of a particular application. Interactions can accelerate the degradation of collection objects, or, alternatively, materials can be selected to prioritize a stable environment. Material choices also impact the financial sustainability of institutions, the health of those working with the materials, and the heritage preservation profession’s impact on the long-term survival of our planet.

What are the Factors to Consider when Choosing Materials?

The potential for positive and negative impact resulting from material choice can make the decision-making process overwhelming. These pages aim to provide tools to help heritage preservation professionals make wise, informed choices. The initial content for these pages, as well as on-going oversight, comes from AIC’s Materials Selection & Specification Working Group (MWG). The group continues to work towards developing additional resources to aid institutions of all types in making the most appropriate choice for their needs. New resources as added to these pages as they become available.

The MWG is a community of collection care, conservation, analytical science, and allied professionals united in developing guidelines and best practices for selecting, evaluating, and disseminating information about materials used in collection care. Learn more about the MWG's work and participants.

When making a material choice, these five categories must be considered if you wish to arrive at a decision that is the best choice for the situation at hand. Deciding before considering all topics is likely to lead to a choice that only works for some stakeholders.

1. Physical Characteristics and Working Properties
2. Financial, Logistical and Operational Accessibility
3. Health and Safety
4. Environmental Sustainability
5. Chemical Stability

Physical Characteristics and Working Properties

When we begin searching for the best material to use for a specific task, we may already know what general physical characteristics we want that material to possess. These criteria can be a good starting point in making decisions. For example, we might need something that fits a specific appearance, such as a case fabric of a certain color or texture. Or, we may be looking for a material that must exhibit a particular strength, such as a board or a laminate that could be used in the construction of a platform for a large or heavy object. A material may need to have certain working properties, or even be compatible with certain tools or building features. By determining how a material might need to look or function, we can begin to make decisions and narrow selections.

Financial, Logistical & Operational Accessibility

In a perfect world, we would choose to use the highest quality material available; one that provides the maximum level of confidence concerning chemical and physical stability, environmental impact, and health and safety (see below). In our imperfect world, restrictions outside these parameters may play a dominant role in material choice.

The nature of a ‘high quality’ material often equates to high cost. Compromise and concessions will often be required and this is OK as long as decisions are well-informed and risk vs need are weighted effectively. Sometimes, we know what we want but we can’t get it. Agreements, shipping details, availability, and other mundane logistics can limit our options. Your time spent holds value as well so balance the need with what is reasonable and practical.

Finally, even when you can afford and can receive the highest quality material, operational restrictions may create hurdles or even complete barriers. Local fire restrictions may prevent the widespread use of plastics in collection spaces, security may require storage in safes or vaults that may not be constructed of materials of choice, health and safety protocols may place restrictions on movement or handling of collections further complicating decisions.

Take all of these variables into consideration when choosing your materials; they are all important and should not be diminished. Maintain a healthy dose of pragmatism and realism and know that decisions on material use aren't made in a vacuum. Be creative in how you manage these hurdles - if you think on it hard enough, there’s always a workable solution!

Health and Safety

Using materials that do not cause health and safety risks for those who use them is a primary factor in making choices. Make sure to read and evaluate all Safety Data Sheets and conduct a Job Hazard Analysis when considering use of a new material that you are unfamiliar with or one that could create risks like the generation of heat, vapors, gasses, or fumes, dusts, and other byproducts. Check to make sure that you have an appropriately outfitted space in which to work with the materials you choose; for example, exhaust fans and personal protective equipment are necessary when working with some resin mixtures and when cutting some types of solid boards.

Environmental Sustainability

The work we do and the materials we use have an impact on our natural environment. Whenever possible we select materials that reduce our negative impact. This may mean using products that can be reused and repurposed, or actually repurposing products in our work. Using lumber from a demolished exhibition wall to build parts of shipping crates is one example of repurposing. We may be able to incorporate ways to reduce our collective carbon footprint into purchasing decisions. This may mean purchasing products that are produced locally, or made from biodegradable materials, or can be 100% recycled. We may also opt not to use a product because its disposal is particularly hazardous. AIC's Sustainable Practices Wiki pages have general tips for sustainable material use and another with information on specific materials.

Sulfur from the air and from silk degradation products caused dark tarnish on silver knives. Image credit: Photograph by van Aubel van Rooijen

Chemical Stability

Materials used in storage, transport, and display can be a source of chemical compounds that are damaging to heritage objects, particularly as those materials age. These compounds include organic acids, sulfides, oxidizing and other gaseous pollutants that interact with sensitive objects in harmful ways:

• wool contains sulfur that will cause silver to tarnish;
• acids in wood will cause many metals to corrode and textiles to yellow.

When storage materials are in direct contact with objects, other interactions can occur. For example, plastics can release plasticizers that will stick to neighboring surfaces. These interactions can be complex and difficult to fully characterize. Nevertheless, they can be reduced or avoided altogether through the careful selection of the materials that are brought into close proximity with objects. Information about a product’s composition and materials testing results are key resources for selecting materials with the long-term stability needed for a particular application.

The MWG's Image Gallery documents deterioration or damage caused by the use of inappropriate or incompatible materials. The images and associated information are presented as a learning resource.

How do I Prioritize these Factors?

How you might prioritize the four factors above will depend on how you assess risk. This assessment depends on three additional lenses as defined by J. Tétreault.

1. Vulnerability
2. Threat
3. Context

In this figure from the CCI Technical Bulletin 32 we see that damaging acetic acid emissions of some paints and sealants level off after off‐gassing for about a month. But the cellulose acetate film which starts out stable begins off‐gassing after decades as it begins to break down

Assessing Vulnerability

Some collections are more vulnerable to pollutants or degradation mechanisms. Understanding where your object sits on the vulnerability scale will help you determine how much weight object vulnerability needs to have in your decision making process. The resources below can assist you as you seek to determine object vulnerability.

The Canadian Conservation Institute’s Technical Bulletin 32 - Products Used in Preventive Conservation by Jean Tétreault provides three tables that are important in assessing vulnerability of our collections

• Table 1: vulnerable objects and damage caused by airborne pollutants emitted from products - Use this table to determine what kind of products (e.g. wood products, foams, cleaning solutions) will off-gas pollutants (e.g. ammonia, acetic acid, hydrogen peroxide) and what collections would be most affected (e.g. metals, limestone, lead glazes)
• Table 2: damage due to direct contact - Use this table to examine what kinds of products can cause staining, corrosion or rust in physical contact with collections
• Table 3: physical damage by incorrect use of products - details damage that occurs to the object by incorrect use of products

The Storage at a Glance chapters in the 2019 Preventive Conservation: Collection Storage book provides useful charts highlighting which collections are vulnerable to pollutants.

Assessing Threat from Products

When you employ a multi-layered approach in storage, you can make modifications at the room level, shelf or drawer level, and object level according to your specific collection’s preservation and protection needs. If your building envelope is deficient, or your storage environment sub-optimal, can you invest in good quality cabinets? If not, move in a level, and focus in on high-quality enclosures? If you can’t afford the archival boxes that you feel might be ideal, can you use a good quality material for the layer that touches the artifacts? Using this approach allows you to weigh the importance of the four factors in a way appropriate for your needs.

Understanding to what an object is vulnerable, as well as just how vulnerable, we can then examine potential products to consider whether they have the physical properties (e.g. strength, flexibility, abrasiveness) and chemical composition that will be compatible for their intended use. That information may be available on product spec sheets, by speaking to manufacturers or distributors, and sometimes information can be gleaned from the Safety Data Sheet [insert image]. This information can also be important to examine how the material will age or perform over time. Some materials can off-gas damaging emissions at the beginning of their “lifetime” and may be safer to use after this period is over. Other materials become dangerous as they age and deteriorate.

Recycled products will be better for the environment but they are essentially at an unknown point in their “lifecycle” and therefore could age less predictably than “virgin” products. On the other hand, they could have desirable physical properties.

Assessing Context

CCI’s Technical Bulletin 32 identifies three main parameters important in determining the probability and extent of damage by materials:

1. "Contact: the proximity between a product and an object and whether or not they touch each other
2. Enclosure: the surface area of the emissive products in the enclosure compared to the volume within the enclosure and its airtightness
3. Length of exposure: the length of time a product and an object occupy the same location and can interact with each other”

A product that that might cause damage if used to construct or within an airtight vitrine might not cause damage in the more open environment of a storeroom. You may be able to use a more economical or lower grade material if it is not in direct contact or will only be for short term use like transport.

Bubble wrap may be appropriate for short term transport but a more stable material like acid free tissue could be used in between the plastic wrap and the item’s surface. This stone piece was stored in bubble wrap for decades. Leaching plasticizers left residues on the surface. Courtesy of Special Collections and Archives, Reed College.

How Do I Choose What To Use?

There are many tools available to assist those making material choices. Which tool(s) you use is guided by your level of expertise, available time, and other resources. It is possible you have arrived here already knowing the kind of support you need to come to a decision. You might wish to:

• Select from lists of already tested and/or frequently used materials
• Research and test materials on your own
• Work directly with a collections care professional

A variety of possibilities within each of these choices are listed below.

Select from lists of already tested materials

• AIC's Materials Testing wiki page provides links to databases of tested materials
• Products Used in Preventive Conservation – Technical Bulletin 32 by Jean Tétreault
• Preparation, Art handling, Collections Care Information Network (PACCIN)’s Material page is a compendium of materials commonly used to wrap, pack and protect art and artifacts. Each material entry has a detailed article providing information on how the materials can be used and how they react, both positive and negatively. PACCIN's forum is a searchable forum to view and participate in discussions on materials used for packing for moving and storing artwork.
• The British Museum Oddy testing report site contains the link to the published database of material test results, including Oddy and pH tests to help with decisions on determining if materials are safe to use with objects inside showcases, packing crates or storage areas.
• Storage Techniques for Art, Science and History Collections (STASHc) details storage solutions for a wide variety of collection types.

Research and test materials on your own

• Conservation & Art Materials Encyclopedia Online (CAMEO) is a searchable information resource developed by the Museum of Fine Arts, Boston. The materials database contains useful chemical, physical, visual, analytical, safety and environmental information on historic and contemporary materials used in the production and conservation of artistic, architectural, archaeological, and anthropological materials. Material entries created by the MWG are collected in CAMEO's MWG Reference Collection and include links to materials testing results when available.
• AIC's Materials Testing wiki pages describe various ways to analyze materials for identification and evaluation, including Oddy Test, Photographic Activity Test, microchemical testing, and multispectral imaging.
• Review literature from the manufacturer - technical data sheets often provide useful information.
• Speak to the vendor you might purchase the material from. Vendors, particularly conservation vendors, are often willing to research questions you might have.
• Review Safety Data Sheets
• AIC's Sustainable Practices wiki pages provide information on sustainable conservation practices

Work directly with a collection care professional

• Ask colleagues through the Connecting to Collections Care Forum - this can help you initially identify a few options which can then be further investigated
• Hire a conservator/conservation scientist for guidance - investigate options using AIC's Find an Expert search feature.

These pages do not provide a single list of recommended products because there is not a single correct answer to the question, “What should I use?” There are materials that are more or less likely to damage collections objects. There are objects that are more or less likely to be damaged. There are materials that are more earth friendly, more human friendly, and/or more budget friendly. You have to consider all of these things in order to make the best decision for you. We hope the resources mentioned here guide you to making smarter decisions about what to use and where to use it.

Resources

Below you will find a curated list of resources to assist you in the decision making process as you choose materials to use in the storage, exhibition, and transport of cultural heritage objects. The resources, despite their publication date, provide accurate and up-to-date information. They primarily focus on material properties, testing methods, and test results. The final section directs you to relevant organizations that are dedicated to continuing research and supporting people in the practice of sustainable preservation and collection care activities.

Each entry has been standardized and includes:

1. Resource title with hyperlink, type of resource (database, article, technical bulletin, etc.), author/creator
2. ONE sentence describing the resource’s contents
3. Optional: ONE sentence suggesting how the resource is often used

If you’re looking for recommendations for specific material specialties, please go to their page on the wiki.

Material Recommendations

The materials listed in the publications below are generally accepted for use in archival situations, given the caveat that the manufacturing process occasionally changes without the knowledge of the end user.

• Products Used in Preventive Conservation – CCITB 32 is a technical bulletin by Jean Tétreault, Canadian Conservation Institute (2017). This bulletin provides a critical review of products typically used for the display, storage and transportation of objects by explaining how certain products can affect objects and their preservation, and proposes guidelines for minimizing damaging effects. Products used to treat objects are not covered here, nor are electronic features such as lighting and security devices.
• DP3: Digital Print Preservation Portal is an online research portal by Image Permanence Institute. This page makes recommendations for storage enclosures specifically for digital prints, but its use of ISO standards makes the information relatable to many types of photographs or works on paper.

Material Properties

The entries in this category provide information on the physical and chemical characteristics, and working properties of materials commonly used in sustainable preservation and collections care.

• Conservation & Art Materials Encyclopedia Online (CAMEO) is a searchable database developed by the Museum of Fine Arts, Boston. The materials database contains useful chemical, physical, visual, and analytical information on historic and contemporary materials used in the production and conservation of artistic, architectural, archaeological, and anthropological materials.
• Agent of Deterioration: Pollutants is an online article by Jean Tétreault of the Canadian Conservation Institute (2021) which provides information on how materials may create pollutants that affect the environment surrounding the cultural heritage.
• The MEMORI project is a reference resource and online air quality calculator. MEMORI created a dosimeter, provides information on museum pollutants, and offers a practical and reliable way of determining the long-term air quality risk to heritage objects indoors.
• Material, Supplies and Tools is a searchable reference table maintained by Storage Techniques for Art, Science and History Collections (STASHc). The table details storage-related materials and information on common materials found in conservation, with a cross reference of brand names, manufacturers, and suppliers.
• PACCIN’s Material index is a compendium of materials commonly used to wrap, pack and protect art and artifacts, created by PACCIN (Preparation, Art handling, and Collections Care Information Network). Each material entry has a detailed article providing information on how the materials can be used and how they react, both positive and negative. This resource is useful for getting a sense of how cultural heritage professionals feel about the use of something and any changes in observations or accepted material use.

Materials Testing - Tests

The tests described in the publications below provide procedures for analyzing and identifying materials used in the storage, transport and display of cultural heritage.

• Materials Testing page is a hub on the AIC wiki that describes various ways to analyze materials for use near art and provides links to more information. Micro-chemical testing, Accelerated Aging tests, and Instrumental Analysis are discussed.
• Using AD Strips is an online article about AD strips, which were developed and produced by the Image Permanence Institute as a way to provide a simple and safe method for detecting, measuring, and recording the severity of "vinegar syndrome" in acetate photographic film collections. The color-changing indicator reacts in the presence of acidic vapors, and can detect (but not quantify) acidic off-gassing in collections.
• International Symposium on the Testing of Materials for Storage and Display of Cultural Heritage is a series of recorded presentations given at the 2019 meeting, organized and hosted by the Metropolitan Museum of Art, New York. With eleven speakers, the symposium garnered fruitful discussion about the needs in the field of preventive conservation to improve our ability to accurately evaluate a broad array of materials for those with and without advanced analytical capabilities.

Materials Testing - Results of Cultural Heritage Testing

This category includes the results from tests run on specific materials related to cultural heritage.

• The IRUG Spectral Database is a compilation of reference spectra for artists' and cultural heritage materials produced and maintained by the Infrared and Raman User Group (IRUG). Material types represented include carbohydrates, minerals/inorganic pigments, mixtures, natural resins, oils/fats, organic dyes/pigments, proteinaceous materials, synthetic resins, unclassified materials, and waxes.
• British Museum Oddy testing report site contains the link to the published database of material test results, including Oddy and pH tests to help with decisions on determining if materials are safe to use with objects inside showcases, packing crates or storage areas.

Product Certification Program Results

These recognized third-party testing programs are used to vet building materials and other products from environmental and healthcare perspectives. Certification by these programs can inform materials choice for use around cultural heritage collections.

Standards & Specifications Organizations

These resources provide standard methodologies used in industry. There is a growing number of standards designed for the museum field. If you’re looking for standards for specific material specialties, please go to their page on the wiki (http://www.conservation-wiki.com/wiki/Materials_and_Treatment)

Bibliographies

The following contain references specifically related to choosing materials for storage, exhibition, and transport.

Organizations and Networks

The following produce and present research related to choosing materials for storage, exhibition, and transport.