Core Documents

Commentaries to the Guidelines for Practice

Commentary 22 - Materials and Methods

  1. Rationale
    • Some materials and methods used in the past have had a detrimental effect on cultural property, sometimes causing further deterioration and interfering with use of newly developed analytical techniques and treatments. Often the selection of materials and methods was formulaic, and not made on the basis of appropriateness to the individual cultural property being treated. It is therefore important that materials and methods be chosen that both meet the specific needs of the cultural property being treated and take into consideration the future availability of better analytical and treatment techniques.
    • Using materials and methods that are consistent with currently accepted practice will help the conservation professional to avoid the adoption of insufficiently tested materials and methods and to determine whether the use of existing materials and methods is appropriate in new treatment situations. Materials and methods become recognized as currently accepted practice through appropriate testing and publication in peer-reviewed literature. This process provides an understanding of the characteristics and properties of the materials and methods, especially their aging properties. Although selecting only those materials and methods that are accepted limits the conservation professional's repertoire, it enhances the possibility of sucessful future retreatment or analysis.
  2. Minimum Accepted Practice
    • Currently accepted practice is not static. Because of the changing and advancing nature of knowledge and practice in the field, all conservation professionals must continue to review the literature, monitor and review past treatments, and share with colleagues their experiences-both practical and experimental-through discussion and publication.
    • The goals of treatment must be clearly defined so that appropriate methods and materials can be chosen. The materials chosen must be:
      • chemically and physically compatible with the cultural property;
      • distinguishable from the materials of the cultural property (see Commentary 23, Section B);
      • removable with the least damage to the cultural property when removing the material becomes necessary;
      • the most chemically and physically stable of those appropriate; and
      • should not preclude retreatment or future analysis of the cultural property.
    • The methods chosen must be within the range of competence of the conservation professional. If an appropriate method does not fall within the competency of the conservation professional, then the treatment of the cultural property should be referred to a properly qualified conservation professional.
    • When no currently accepted material or method is available, treatment must be deferred and preventive conservation approaches used to stabilize the cultural property.
    • The conservation professional must distinguish among those materials and methods that are part of currently accepted practice, those that have been superceded, and those which are still experimental. Materials and methods become part of currently accepted practice through:
      • replicable research;
      • objective review of past practices;
      • professional consultation and open discussion at professional meetings;
      • industrial information (e.g., ASTM, ANSI); and
      • publication in peer-reviewed literature.
    • Where the wholesale application of a material or method to cultural property is contemplated, testing must be conducted on a small, unobtrusive section of the cultural property, or on mock-ups.
    • Representative samples of original material of the cultural property removed during treatment must be retained with the cultural property, in a file, or with the owner/custodian.
    • All material removed from the cultural property must be documented.
  3. Recommended Practice
    • When considering a newly published or unfamiliar material or method, the conservation professional should become informed through discussion with colleagues, personal education, field testing, and consultation with other appropriate professionals.
    • Conservation professionals should be conservative in embracing the use of new materials and methods, and it is their responsibility to understand the consequences involved in their use.
    • Conservation professionals should participate in experimental evaluation of materials and methods in the laboratory or in field tests using mock-ups or original materials commonly considered to be historically, culturally, and aesthetically insignificant. The experimental use of materials and methods on significant cultural property is a topic requiring further discussion and debate within the field.
    • Representative samples of significant non-original material of the cultural property removed during treatment should be retained with the cultural property, in a file, or with the owner/custodian.
  4. Special Practice
    • In emergency situations, when there is a possibility of imminent loss of the cultural property, it may be necessary to use materials or methods which are not currently accepted practice.
    • In situations where there is active deterioration and preventive conservation measures will not prevent imminent loss, it may be necessary to use experimental materials or methods.
    • When treating certain sacred objects, it may be necessary to employ traditional materials and methods that may not be recognized as currently accepted practice.
    • In some circumstances it may be advisable to employ materials and methods that are sustainable by local communities, even if they are not recognized as currently accepted practice.
    • In some cases it may be necessary to use materials indistinguishable from the original materials of the cultural property (e.g., hide glue, wheat starch paste, lime mortar, gold leaf). These cases require more extensive documentation.
    • In situations where materials will not be removable from a cultural property (e.g., consolidants), where there will be substantial chemical alteration of the cultural property (e.g., image enhancement of photographs, bleaching, patination), or where the cultural property will be used, thus requiring more robust materials (e.g., carriages, automatons, industrial machines, books), most careful consideration should be given to the choice of materials and methods, in collaboration with the owner/custodian. These situations require more extensive documentation.
    • If it is not feasible to retain all removed material, representative samples should be retained and well documented.


Approved by the AIC Board October 1997.