Core Documents

Commentaries to the Guidelines for Practice

Commentary 23 - Compensation for Loss

This guideline refers to physical loss to the material of a cultural property or loss of original appearance through chemical change. Loss may have a structural and/or visual effect. The baseline for determining the nature and extent of loss is the point at which the cultural property was generally accepted as completed, although compensation need not return the cultural property to this state. The original completed state (what the artist/maker actually did) takes precedence over the artist's/maker's original intent in guiding the nature and extent of compensation for loss.

  1. Rationale
    • To restore:
      • structural stability;
      • visual unity; and/or
      • function and use.
    • To facilitate the understanding and appreciation of the cultural property. (e.g., sounds of a musical instrument, shape of a broken vase, movement of an automaton).
    • Compensation for loss must be detectable because:
      • the viewer may otherwise be deceived as to the nature and extent of compensation, and the condition of the cultural property, which may affect evidential and monetary value; and
      • conservation professionals must be able to differentiate between original material and later additions when carrying out research and treatment
    • Compensation for loss must be reversible because:
      • more appropriate materials used for compensation may become available;
      • compensation is the aspect of treatment most often based on supposition;
      • new information may indicate that the compensation should be modified;
      • taste and fashion in presentation will change; and
      • damage to the cultural property is minimized during retreatment.
  2. Minimum Accepted Practice
    • Compensation must be documented in written and graphic form. Location of compensation and materials used must be clearly identified.
    • Compensation must be detectable using at least one common examination method. These methods (as employed by conservation professionals) are presently considered to include:
      • examination in visible light;
      • examination in UV radiation; and
      • examination under low-power magnification.
    • Compensation must be reversible, using chemical and/or mechanical methods that will not adversely affect the remaining original material, unless this jeopardizes structural stability. An isolating layer often facilitates reversibility.
    • While all compensation covers some original material, compensation must cover as little of the original surface as possible.
  3. Recommended Practice
    • The method of detecting and the means of reversing the compensation should be specified in the documentation.
    • Compensation should be detectable by the educated viewer.
    • If compensation is so extensive that it forms a substantial portion of the cultural property, then the compensation should be visually apparent to all viewers. In some cases, where long-standing traditional compensation techniques produce results that are not readily apparent (e.g., tapestry re-weaving, replacement carvings, furniture veneers), then thorough documentation is especially important.
    • If compensation is based on supposition because sufficient historical documentation or contextual evidence is unavailable, then compensation should be readily apparent to all viewers.
    • In some cases a better aesthetic result may be achieved by compensation that removes or covers substantial original material or surface. However, the conservation professional should select a method of compensation that favors retention of original material over marginal aesthetic improvement.
    • Significant non-original material that is removed prior to compensation should be documented, and representative samples should be retained.
    • Materials used for compensation should be clearly distinguished, physically or chemically, as an addition (e.g., dots on replacement shells, stamps on new watch parts, barium in gesso fills, marks on replacement windows).
  4. Special Practice
    • In the treatment of contemporary cultural property, the aesthetic requirements of the maker/artist may necessitate compensation practices that sacrifice original material and surface to obtain a specified result. The conservation professional should document the rationale for such a treatment.
    • Compensation for losses to some sacred and ceremonial cultural property of living cultures may require more extensive intervention to restore conceptual meaning. The conservation professional should document the rationale for such treatments.
    • Some compensation processes may not be reversible. These include:
      • repatination;
      • redying;
      • chemical enhancement of photographs;
      • inpainting of watercolors on paper;
      • epoxy fills; and
      • replastering of walls and the application of cementitious materials.
    • These compensation processes should not be used until all reversible options have been considered. The rationale for the use of non-reversible processes should be well-documented.
    • If compensation is so extensive that it covers a substantial portion of the original surface, a representative example of the historic surface(s) should be retained in situ (e.g., architectural finishes, repatination).
    • In some cases (e.g., period rooms, vehicles, monuments) where the surface is very badly damaged or substantially covered, the cost of retaining or revealing the surface may be prohibitive. Although the conservation of original surface is usually of paramount importance, in such cases as much of the original surface as possible should be retained and isolated even if it is to be completely overpainted.
    • In some instances the use of a new material that obscures or replaces the original surface may be necessary (e.g., leaf casting, repatination, architectural finishes), and may not be detectable by common examination methods. Documentation of the original surface is essential, and photographs (e.g., before and after treatment) and other graphic documentation must show the extent of compensation. The rationale for the sacrifice of original surface should also be well-documented.


Approved by the AIC Board October 1997.