4 CONCLUSIONS

IT WOULD BE HAZARDOUS to conclude from this research that solvents are entirely safe for use on paper. It is perhaps an overgeneralization even to conclude that no paper will ever retain a solvent permanently. However, the results of this investigation do indicate that most ordinary solvents will not be retained by the cellulose in paper under a normal museum environment. Thus, if solvent treatment accelerates paper aging in general (a phenomenon not yet established), then such an effect coult not be attributed to the formation of a permanent cellulose-solvent complex.

Thymol is of particular interest in the context of retained organic matter. If thymol is not retained in papers, its fungicidal activity would be lost. Thus, a thymol treatment might inhibit the active growth of mold, but prolonged protection from mold growth would not be expected. The retention of thymol would not be desirable in any case, however, because thymol suffers oxidative decomposition to a brown, oily material in a relatively short time. This phenomenon, often observed to occur in trays of thymol used in treatment chambers, would be a problem only if significant levels of thymol were retained in papers for prolonged periods. Although it is possible that a long-term decomposition of thymol might occur within some papers, particularly those treated with thymol-alcohol solutions, the problem is not expected to be of significance in the usual vapor-treatment process, particularly if the treated paper is thoroughly vented in a moist (50% RH) atmosphere.