GLOSSARY OF TERMS

Abrasion – Damaged area of upper paint layers, resulting from scraping, rubbing, or grinding away. 

Accretion  - Accidental surface deposit of known or unknown origin (e.g., flyspecks, spatters).

BEVA – A binding agent/ consolidant used in conservation that comes in liquid or film form.

Blister – Bulge in the paint surface indicating cleavage of paint or ground layers either from each other or from the support.

Bloom – Hazy, bluish white cloudiness that appears on varnished paintings; results from the breakdown of the consistence of the coating by moisture or other pollutants.

When it occurs on an unvarnished surface it is called “Blanching”.

Buckling – A distortion of the picture plane often accompanied by a rupture in a paint or ground layer, caused by shrinkage or compression. The canvas is often slackened on the stretcher.

Check – A break in wood, running along the grain, an incomplete split.

Chalking – Loss of pigment in a paint layer by powdering off; results from either an insufficient quantity of binding medium in the paint when it was originally applied or the loss of the binding medium as a result of damage or deteriorating conditions.

Cleavage – Any separation between or in any of the laminated layers of a painting. It is a loss of adhesion. Active cleavage – A separation which is about to flake off. Blind Cleavage – A separation (like buckling) also called a Flat cleavage, which has no visible rupture. Incipient cleavage – The beginning of a separation, layers curled up but not quite free.

Cracking, Craquelure – A pattern of fracture lines caused by movement either of the films or of the layers adjacent to them. Age cracking - Fracture lines due to desiccation, usually penetrating all layers to the final support. Drying cracking – (also called Traction) Resembles alligator patterns or the surface of an orange peel. They are caused by the application of a quickly drying layer over a slower drying layer. They can occur in the paint films, the varnish, even in the ground. Their intervals are wide. Mechanical cracking - Fracture lines which result from a blow or dent and usually assume a cobweb-like pattern, or those resulting from a scratch or rub which have feather lines. These are both accompanied as a rule by a distortion of the picture plane visible in raking light.

Crazing – A very fine system of cracking in a varnish or paint film which appears slightly opaque. It is found in aged films which are very dry and are approaching their final stages of embrittlement. It can powder off.

Curling or Cupping – Paint layers which are islands with their edges lifted and raised away from each other or from lower layers. Strong cupping of cracking paint can distort a support.

Dent, Dig, Gouge - Defect in the surface caused by a blow; a dent is a simple depression in the surface, a dig implies that some material has been displaced, and a gouge indicated material has been scooped out.

Draw – Wrinkles or ripples which radiate from edges and corners of stretched paintings on fabric.

Dry Rot - Decay of seasoned timber caused by fungi that consume the cellulose of wood, leaving a soft skeleton that is readily reduced to powder.

Efflorescence – Powdery surface crust that is formed when substances in plaster or varnish migrate to the surface and crystallize upon contact with air.

Flaking – The loss of sections from one or more layers of a painting above the support.

Foxing – Brown or reddish brown spots caused by mold or the oxidation of iron particles in a paper support, mount, or backing.

Grime – Dirt of any kind, on top of paint, on top of varnish, buried under varnish.

Hollitex – A very strong synthetic paper like material.

Impasto – Thick, often opaque area of paint that protrudes above the surface to which is has been applied.

Inpainting – Introduction of new paint material into areas of loss in an original construction.

Key – The triangular wooden wedge employed in the slot at the inner joint of a stretcher to enlarge its outer dimension mechanically.

Lining – Attaching a new layer of support to a picture as a strengthening measure.

Loss – A missing area in one or more layers (even all) of a painting.

Overpainting – Addition that wholly or partially covers original paint.

PeCap – Monofilament fabric.

Pentimento – Phenomenon in which the translucency of upper paint layers allows for the emergence of tones beneath. As the index of refraction rises, more light penetrates the paint layer, and the drawing and underpaint, once concealed, show through.

Rabbet – The inner grove behind a frame opening, planned to receive the painting.

Raking light – Illumination from the side at a low angle, thus throwing long shadows. Used in restoration photography to show surface irregularities.

Strainer – An auxiliary support of wood over which fabric is attached which is fastened tight at all joints.

Stretcher - An auxiliary support of wood over which fabric is attached which is tongued and slotted at its joints to permit dimensional enlargement.

Stretcher crease – An impression on the paint surface of the form of the stretcher bar. Although the impression is not always marked by a cracked or cupped surface, the edge of the stretcher sometimes causes fairly continuous parallel straight cracks on the surface. Stretcher creases generally occur in a picture whose support is slack.

Tacking edge – That part at the extremities of a fabric used for a painting which is planned to be turned over the sides of an auxiliary support and serve as a means of attachment.

Tenting – Lifting up of paint from a support into a small tent shape.

VHT (Vacuum hot table) – A heated plate with suction device and electric heating element. Paintings are laid down on them between layers of clear film and the air is extracted with a vacuum pump and sucked down flat to the surface of the heated plate.

Void – A loss in painting structure, usually applied to a loss in all the layers above the support. It must be filled to surface level before inpainting.