5 LOCAL TREATMENTS

Another development of interest is a concern for the local as opposed to the overall introduction of moisture and solvents or the agents for which they serve as vehicles, such as bleaches, enzymes, and alkaline agents. The premise is that if local areas of a sheet of paper are treated differently, with age a different condition or appearance may result. Despite the use of very limited moisture, soluble substances may move about a sheet and deposit in a tideline not visible in normal viewing conditions but plainly visible under ultraviolet light. The introduction of very focused steam pencils facilitates the local removal of adhesives without having to resort to enzymes or more saturating poultices. For the same reasons, efforts are made to minimize the need for solvents. Hot-air pencils followed by crepe or high solvent-content erasers are very effective in the removal of self-adhesive tapes. Residual adhesives can also be exposed to solvent fumes and rolled up with paper pulp.