“It was thrilling to observe closely the expressive brushstrokes that Grimshaw employed to depict moonlight” The conservator’s story: Five paintings by John Atkinson Grimshaw (1836-1893) came to Critchlow & Kukkonen’s studio in 2019 to undergo conservation. They had an overall deposit of surface dust and dirt, obscuring the images to some extent. In conservation, the objective of cleaning is to remove dirt, dust and grime – material which is in the wrong place – without removing material which is in the right place. This is an important part of the stabilising process: dirt may be a source of deterioration. The verso of the canvases was cleaned using a museum vacuum. Debris was removed from behind the stretcher bars with a palette knife. If the method of securing keys to the stretcher was adequate, it was retained; otherwise the expansion keys were secured with monofilament line and brass screws and cups. Surface dust and dirt was removed from the front of all the paintings using cotton wool swabs and an aqueous solution (de-mineralised water and a chelating agent when needed). During this stage, the conservator familiarises themselves even more with the painting details and artist technique. With these five paintings in particular, it was thrilling to observe closely the expressive brushstrokes and tonal modulation that Grimshaw employed to depict moonlight. In all but one, the oil paint had been applied in thin layers using ‘wet in wet’ tonal modulation, and thickly impasto and expressive brushstrokes were employed for highlights and details such as the sun, lights, the fire, and reflections on the water. In Lights in the Harbour, the oil paint has been applied fairly thickly, with impasto employed for details such as reflections on the water. The four seascapes presented a discoloured varnish layer which fluoresced milky-green under UV light, suggesting the presence of a natural resin. Some have had structural work done in past restoration: insets filling missing areas of canvas, lining, and a stretcher bar lining. The paintings had several areas of disturbing retouching from past restoration campaigns, visible not only under UV light, but also in normal light. Some of the retouching had discoloured and become milky, and did not match the surrounding original paint. There were also some small recent damages including paint and ground losses. Losses in the paint and ground layers were filled up to the level of the original paint layers, and the fills carefully textured to match
the surrounding original paint. Retouching was carried out with powdered pigments bound in a synthetic resin, including adjusting discoloured retouching in order to match closely the surrounding original paint layers, in-painting small losses, and applying glazes to small paint layer abrasions along the edges. The paintings were spray-varnished with a semi-shiny final synthetic resin varnish layer. Dirt and dust was cleaned from the frames with a brush and museum vacuum, and small losses to compo were retouched. Whenever the previous conservation framing was adequate, this was retained. Otherwise, the frame rebate was lined to provide cushioning and protect the surface of the painting from abrasion; the painting was carefully spaced with balsa wood spacers pinned to the sides of the rebate. They were then secured to the frames with either brass mirror plates or framing strips. All five paintings have hardboard backings. The hardboards were lined on the inside with Mylar polyester film, to reduce the amount of volatile organic compounds which are emitted by the hardboards from reaching the reverse of the paintings. The backings provide protection against dirt, impact, and minimise vibrations during transport.
Glossary Verso: the back, or reverse, of a painting Museum vacuum: a compact and lightweight vacuum cleaner, specially developed to conservation standards Stretcher bars: a framework, usually wooden, which keeps a canvas taut and maintains its shape Expansion keys: also known as canvas keys, small wedges of wood which are inserted into the corners of the stretcher bars if the canvas begins to sag Chelating agent: chemical compound used in specialist art conservation Wet in wet: the laying down of one colour beside or over another before the first layer is dry. Because both paints are wet, the colours intermingle Impasto: from the Italian for dough – areas of the surface of a painting which are heavily built up with layers of paint Compo: also known as gilders’ composition – a mouldable resin used by gilders and framers to created moulded ornamentation for picture frames