Glossary of Art Conservation Terms for Oil Paintings
Abrasions: Loss of media (and often the ground) caused by rubbing or scraping.
Aging Cracks: Visible stress as a result of adverse environment conditions, mechanical or other causes that have developed over an extended period of time. The cracks are through all the layers of a painting beginning with the support. The individual cracks or fissures can form a network pattern of straight or barely curved lines.
Buckling: Disruption causing ripples or ridges in canvas.
Cleaning: To remove aged and discolored varnish; to remove dirt, grime or accretions.
Note: although considered by many to be a benign and routine procedure, cleaning ranks among the most dangerous of painting restoration processes in unskilled hands.
Cleaning Rear of canvas: Removing accumulated dirt, dust and grime reduces both damaging weight and tension on the canvas, ground and paint layers while removing acidic materials which physically degenerate the canvas. It must be removed in alternating small squares to avoid damaging excess tension from developing in the canvas, ground or paint.
Cleaning Test: Tests performed upon the varnish layer to determine the precise blend of solvents or enzymes, which will successfully remove the varnish (clean the painting) without also removing paint. The results are often dramatic.
Consolidation: Procedures to re-adhere flaking or delaminating paint to the canvas.
Cracking: A failure of materials caused by stress.
Crackle: Perpendicular disruption; fine cracks appearing in any of the painting’s layers.
Cupping: Aged paint, loosened by cracking, with edges curling to create cup-like formations.
Embrittlement: Canvas has become perceptibly fragile to the point of snapping, crumbling or breaking.
Facing: The adhesion of a protective layer (most often tissue paper upon the face of a fragile painting) to prevent loss of the paint during conservation, or until conservation is performed.
Flaking: Extreme cracking causing paint and/or ground layer to dislodge from the support, often through a combination of cleavage and cracking.
Inpainting: A restoration process to cosmetically re-establish color and/or detail to losses in the paint layer; generally accomplished with pigment in an appropriate binding medium applied by brush. Also called retouching.
Lining: An auxiliary support applied by a conservator to the original support (canvas, etc.) of the painting when the original support no longer has enough strength to carry the weight of the painting. Linings can be constructed from a variety of material, including canvas, fiberglass etc. and may be rigid, semi-rigid or flexible as the need demands.
Loose paint: Areas of the pigmented layer, which have lost adhesion and are no longer firmly fastened to the surface, but are still there.
Loss: Missing area in one or more layers of the painting; most frequently the result of flaking, abrasion, tearing, etc.
Medium: Base, such as oil, varnish, water, etc. containing the pigmentation and used as a vehicle for the pigment.
Overpainting: Restoration requiring in painting where the restorer does not have skill enough to retouch within the damage area alone without having to extend the restored area substantially beyond the boundaries defined by the damage.
Stretcher: Auxiliary support – fabric over wood, tongued and slotted at its joints to allow tightening.
Stretcher Cracks: Cracks developing in the painting’s corner from over tightening the keys.
Strip Lining: A partial (or strip of) lining confined to the outer edges of the painting when it is necessary to strengthen the edges but not yet necessary to line the entire canvas.
Support: Material providing the foundation for the painting; most commonly canvas or wood, and occasionally metal, masonite or other materials.
Tacking Edge: Edge of fabric on painting used as a means of attachment, turning it over the sides of its auxiliary support.
Tear: A break in fabric as a result of tension.
Tenting: Delaminating of the paint and /or ground along cracks where the delaminated layers lift upward into a pattern resembling the peaked tops of tents.