5 CHANGES TO ORIGINAL MATERIAL

Obviously irreversible treatments like bleaching and structural changes in metals are, properly, subject to a great deal of controversy. An important issue in their use is the degree of predictability the conservator can bring to the choice of treatment methods and materials, and the amount of control that can be exercised in the course of treatment. Issues related to treatment techniques like these perhaps belong to specialists in the relevant conservation field; it is noteworthy, however, that many common conservation techniques (e.g. changes on the pH of paper, sanding the reverse of a canvas support for a painting, attempts to flatten wood panels, etc.) are beyond question irreversible, yet have not often been discussed in these terms.