Materials Identification and Condition Assessment
- How do I determine whether an artifact is stable or deteriorating?
- I have an archaeological collection and I don’t know what its conservation needs are. Where should I start?
- How do I assess whether my storage site is good or bad for my collection?
How do I determine whether an artifact is stable or deteriorating?
Different materials deteriorate at different rates and in varying ways. General signs to watch for when assessing a collection are listed below (Table 5a). This is not a comprehensive list, but rather it is a general start. Information on the most common material types found to be unstable in archaeological collections is given.
| Material Type | Signs of Deterioration |
|---|---|
| Iron | Red/ brown voluminous corrosion; bright red/orange spots; flaking and spalling of iron; corrosion found in bottom of bag |
| Copper Alloy | Blue/ green corrosion products; powdery corrosion, the shape and morphology are obscured or being lost |
| White metal alloys | White and gray corrosion products; object is splitting and cracked, brittle/crumbling along edges; morphology and shape of the object is threatened |
| Bone | Object is dry, brittle, flaking or spalling in sections; surface abrasions; cracks or breaks |
| Leather | Extreme brittleness, fiber loss, surface delamination, white bloom, mold growth (if RH is too high), tears, gaps, and/or losses that threaten structural stability |
| Wood | Dry or moldy surfaces; blooms on surfaces; abrasions; cracks; shrinkage, warping and misshapen pieces, extreme amounts of dust, very sticky surfaces, powdery areas associated with a very low pH |
| Glass | Surfaces appear iridescent; active flaking of surfaces; breaks and damage to the shape; moist surfaces |
| Ceramics | Glazes powdery or flaking; white salts present; cracks in glaze; breaks; decorative elements may be gone |
| Composites | Assess the most fragile material first; two or more materials may be separating or staining one another |
If a large portion of the collection or a large percentage of a specific material within the collection appears to be deteriorating, or if the collection contains large amounts of exotic materials such as horn, jet, ivory or textiles, you may wish to seek advice about assessment and mitigation. Most conservators will wish to start with both a general and a detailed conditioned survey in order to quantify the damage and determine the best course of action.
I have an archaeological collection and I don’t know what its conservation needs are. Where should I start?
Usually an environmental strategy needs to be developed first. Looking at the environment is the best place to start because having a clean, secure and climate controlled area in which to house artifacts is key to their long-term preservation. Performing a general assessment of the environment within the storage area (sometimes called a building survey), will identify any conditions that may be detrimental to collections, and will help to plan and prioritize any changes that may be needed to improve the environment surrounding the artifacts. Because factors in the environment such as temperature, humidity, and light all work together to cause damage, they must be considered at the same time. The environmental survey may need to be carried out by a conservator who is familiar with the architectural elements of the storage area, and the types of equipment that are used to control the environment within it.
Things that may be considered in an environmental assessment include:
- Existing humidity and temperature equipment (HVAC, water pipes)
- Short and long term maintenance of the equipment
- Insect situation
- Pollutants in building/ dust/ debris
- UV radiation or light control
- People, access to building
- Fire, water and disaster frequency
- The suitability of the building, or of a space within a building, for the purpose (i.e. is it worth renovating or should you be looking to move)
A general conservation assessment or collections survey can be performed in conjunction with a general environmental survey. The main goals of a collections survey are to assess the general condition of the collection, to determine the causes of any deterioration, to determine the resources needed to stabilize the entire collection, and to establish a long-range preservation plan. The material types present in the collection should be identified and a sample of the collection should be examined for signs of degradation, which may be due to a combination of poor environment, poor packaging materials, the natural breakdown of the material over time, or lack of post-excavation processing or conservation. If the collection has not been examined before, a more thorough detailed condition survey of the collection would be recommended during the general survey.
A detailed condition survey is performed by a conservation team, and is a more detailed look into the condition of all the objects in the collection or certain material groups. Recording the condition of objects at a designated point in time is imperative if the overall history of the object is going to be archived. Documentation showing the condition of the objects should be consistent and objective and should become part of the permanent archived record of the artifact. If a detailed condition survey is performed, you should work closely with a professional conservator to determine how to record the condition of the materials you have, and to estimate their conservation needs. The data collected can then be used to establish a long-range preservation plan and to integrate the curation and conservation needs of the objects or collection into the overall goals and planning of the museum or institution. A timeline and plan should be a part of the report, which will help you to better reach your collection goals, even if the implementation has to be spread out over a number of years.
Obviously one must either allocate or apply for funding to perform both the general and detailed conservation surveys. One place to start is to obtain a grant to have a general conservation survey done. For more information on conservation assessment funding please go to the section on conservation funding.
Once a survey has been completed, or the objects have been stabilized and/or re-housed, the job is far from over. The collections need to be continually checked for any changes that may be occurring. Additionally, the environment needs to be monitored regularly to ensure that nothing changes adversely. A regular housekeeping program should be put into place if it does not already exist. By using simple cleaning techniques, such as dusting and vacuuming, one can eliminate a number of factors that might pose risks for collections. Regular housekeeping plans should be developed and a manual should be created with do’s and don’ts so that everyone is aware of the proper cleaning procedures. The manual should be updated and reviewed periodically with the staff actually doing the cleaning to integrate suggestions, or to find solutions to problems. It is not desirable to find out that cleaning is not being done properly because what has been requested is poorly understood or too cumbersome.
By using the information generated by the environmental and conservation surveys one can better plan for the future. After a preservation plan is developed it is important to continue doing the right things, and to move forward as outlined in your report, even if it takes longer to reach your goals than anticipated. As in most fields, technology is advancing rapidly, and sometimes equipment becomes more accessible or even cheaper, and what may not have seemed possible at one point may suddenly become feasible. Temporary measures can sometimes be implemented to accomplish goals, until more permanent measures can be secured. However, to ensure that these band-aid measures accomplish the desired effect and do not incidentally make the situation worse, it may be helpful to work with a conservator.
How do I assess whether my storage site is good or bad for my collection?
The suitability of a building for collections storage depends largely on the nature of the collections that are being kept within it. The building serves as the first line of defense against many sources of deterioration. A survey can establish how well the building cushions the indoor environment from that outdoors, and isolates the conditions within. If the building has poor features, yet is capable of satisfactory modification, its physical improvement should come before consideration of new internal control equipment that will be expensive to install and energy-inefficient to operate.
The environment within the building should be surveyed using recording devices placed in a number of locations throughout the building. The recording devices should be deployed for a full calendar year in order to best understand the effects of seasonal change on the structure. An external sensor, to provide contrasting readings, is essential to judge the efficiency of the building fabric. Such a survey may quickly identify the existence of differing environmental conditions within the building. As an immediate response, the collection may be reorganized, and the most sensitive items placed in the most stable and easily controlled zones – for example, in rooms near the center of the building that are usually furthest from the effects of the weather. Any additional control measures that are needed can then be economically and effectively targeted in specific zones, rather than applied indiscriminately throughout the building. It may be that no area within the building can easily be brought to an adequate standard. In such cases, consideration should be given to relocating the storage.
| FEATURE | GOOD | BAD |
|---|---|---|
| Site | Well-drained Sheltered (but not shaded) |
Low-lying. Poorly drained Exposed. Shaded |
| Building Materials | Damp-proof course Well-insulated. Watertight. Good ventilation |
Rising damp Poor insulation Draughty |
| Building Design (external) | Pitched roof. Controllable ventilation. Few windows. External rain water disposal | Flat roof. Large skylights. Large number of windows. Internal pipes & gutters over collections |
| Building Design (internal) | Easy physical access. Fire divisions. Planned environmental zoning. Separation of collection (storage & display) and non-collection areas. Secure areas | Poor access. Open plan. Lack of internal physical & environmental barriers. Mixed use of spaces, causing/requiring compromises |
| Building Design (external) | Pitched roof. Controllable ventilation. Few windows. External rain water disposal | Flat roof. Large skylights. Large number of windows. Internal pipes & gutters over collections |
| Building Design (internal) | Easy physical access. Fire divisions. Planned environmental zoning. Separation of collection (storage & display) and non-collection areas. Secure areas | Poor access. Open plan. Lack of internal physical & environmental barriers. Mixed use of spaces, causing/requiring compromises |
| Building Environment | Stable and moderate RH & temperature, suggesting: – Good buffering effect by shell of building from prevailing weather conditions, and/or – Environmental services control systems that work | Fluctuating or extreme RH & temperature, suggesting: – Poor buffering effect of building fabric, and/or – Environmental services control systems that do not work in desired way. |
| Building Maintenance | Good condition. Preventive as well as repair maintenance. Disaster plan in place. Regular checks and rapid repairs of roofs, gutters, and other elements | Poor repair. No regular checks or reporting procedure. No procedures governing contractor work. No disaster plan |
Copyright © 2006 Colleen Brady, Molly Gleeson, Melba Myers, Claire Peachey, Betty Seifert, Howard Wellman, Emily Williams, Lisa Young. All rights reserved. Commercial use or publication of text and graphic images is prohibited. Authors reserve the right to update this information as appropriate.