ULTRASONIC MISTING. PART 2, TREATMENT APPLICATIONS
CAROLE DIGNARD, ROBYN DOUGLAS, SHERRY GUILD, ANNE MAHEUX, & WANDA McWILLIAMS
5 TREATMENT LIMITATIONS AND POTENTIAL
Although valuable for the consolidation of particles and tiny flakes, the mister, as expected, has been found to be less successful for the consolidation of large flakes of paint for several possible reasons. First, the mist cannot be focused narrowly enough to allow delivery of consolidant into cracks only; a brush can be more successful for this situation. Second, the mister delivers small quantities of dilute consolidant, but flakes often require larger quantities of consolidant at higher concentrations to bridge the gap between flake and substrate. Furthermore, even with a very slow mist velocity, it may be difficult to avoid dislodging flakes. If flakes are powdery, they can be delicately misted with a small nozzle to make them less powdery before being repositioned and fixed to the substrate by other means.
Another limitation of the mister technique is that it is slow. For example, it took 40 hours to set up the mister equipment and do the consolidation for the ink drawing (section 4.4).
The ultrasonic mister is valuable for the treatment of objects considered too sensitive to be treated with “normal” quantities of solvents or moisture or too delicate to be subjected to mechanical action or spraying. The mister is also useful when small local applications are required. For example, it is expected that the mister could be used to apply solvents, bleaching solutions, or cleaning solutions locally to reduce or remove stains or discoloration, to apply a coating or reform an existing layer such as a bloomed varnish, to achieve local humidification and reformation of deformed surfaces, and to aid in the removal of degrading or potentially damaging attachments such as tapes, hinges, and adhesive residues. Because the mister delivers small quantities of solution, it may help prevent localized overcleaning, which can occur if the solvent selected to remove problematic materials also removes the degradation products in the paper support, creating a lighter area.