Conservators are often faced with a basic conundrum of how to make something look better without making it look worse. Water and touch sensitive media such as unfixed pastel and charcoal can present special challenges in this regard. The general rule of thumb when approaching media of dubious stability is to test and approach with caution. In this case the charcoal was somewhat stable to water and pressure and, fortunately, much of the distracting discolouration was in the non-image sections of the piece. This gave me the advantage of being able work around very sensitive areas.

Jean-Philippe Dallaire drawing, prior to conservation treatment

Jean-Philippe Dallaire drawing, after conservation treatment

The paper was first relaxed with gentle humidification. This was done by using Gore-Tex, which only allows water vapour through its membrane. Pre-humidification helps the paper to absorb cleaning solutions evenly and prevents unwanted wicking and tidelines. The non-image areas on the front of the paper were treated with a brush coat of a reducing bleach, sodium borohydride. Sodium borohydride not only reduces discolouration, it also breaks down gelatin sizing making paper more receptive to water treatment. After bleaching, the drawing was transferred to a blotter-covered suction table, and the treated areas were rinsed with deionized water. Areas farthest from the charcoal medium were rinsed with spray and brush-applied water and areas closest to the charcoal were rinsed with heated water vapour mist.

By slowly easing into a treatment, conservators can get a feel for how much (or little) solvent exposure a particular media can safely withstand. My own experience has shown that artworks like the Dallaire drawing, which are moderately water sensitive, can often be cleaned from the reverse without endangering the media on the front. The reverse and non-image areas of the front could be safely misted with diluted hydrogen peroxide and rinsed by floating the drawing very briefly on a deionized water bath. The piece was further rinsed on a blotter-covered suction table. A final application of sodium borohydride neutralized any remaining hydrogen peroxide residue, and the artwork was rinsed again.

Despite being relaxed with water throughout the treatment, the paper support still did not lie flat enough to be pressed dry between blotters. This is often the case with art on paper. Water resistant media (e.g., oil based printing ink) or as in this case, long-term distortion, will prevent the paper from lying flat even when wet. Drying and flattening between blotters would cause creases to be pressed into the paper.

This is when stretch drying can be used to advantage. The edges of the humidified sheets are clamped with blotters and weights. As the paper sheet dries, it shrinks and pulls itself flat. Stretch drying is also useful when flattening pressure sensitive media such as pastel and charcoal. The Dallaire drawing qualified for stretch drying on both counts and was successfully flattened using this method. Although some discolouration does remain in the paper support, this treatment improved the overall appearance while protecting the medium from being damaged.

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