Its surface has darkened and the painting’s colours and image have changed. Paintings can be obscured by layers of grime, accretions, old varnishes, and overpaint from previous repairs.

Aging affects artwork. Time Smoking a Painting, etching by William Hogarth.

If we reflect on the history acquired from aged treatises and writings, we find that intriguing materials and techniques were used to clean paintings. Older methods included rubbing a painting’s surface with a stone block, mastic tears, potatoes, onions, or bread. Washing the paint surface with urine and ammonia, or scouring it with potash or alum was common. A coating of oil on the front and back of a painting was used to “brighten up” its appearance.

In earlier times, artists or laymen would work on art just as a blacksmith would carry out dentistry, as the commonality of tools outweighed the era’s development of a specific expertise.

Household remedies such as washing a painting with dish detergent, spraying it with window cleaner, or using commercial solvent emulsions, are becoming antics of the past. Aggressive techniques or inappropriate cleaning agents can result in the weakening of a painting’s structure, causing flaking or dissolving paint layers. Stripping varnishes and harsh, exuberant cleanings can leave an artwork’s appearance blanched and its structure leached. In other words, antiquated or unskilled attempts to reveal an image may cause it to disappear from history altogether.

Conservator employing a present-day cleaning method on an early 19th C. Ecuadorian icon

Contemporary advancements in our knowledge of the structural science of paintings and the technological development of tools, materials, and methods for cleaning paintings, extend beyond traditional methods employing solvents, emulsions, and scalpels.

Dr. Richard Wolbers’ significant explorations with aqueous intermixtures, surfactants, chelators, enzymes, and solvent gels for use in varnish removal and cleaning paintings, provide additional options for the conservator. Research continues as advancements always create more questions.

Present day cleaning of paintings combines traditional and modern methods and dry and wet techniques directed for specific cleaning concerns. Cleaning paintings requires more than an assessment of the artwork, the selection of the type of cleaning procedures and the materials involved.

A balanced cleaning methodology also incorporates a conservator’s knowledge, experience, objective logic, and humility combined with a respect for the artwork’s integrity and an understanding of the aesthetic and historical context of the painting. As Sarah Walden says in her book, The Ravished Image, “Conservation has never been purely a matter of solvents, recipes, and equipment.…”

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