Welcome to our extensive list of essential terms relating to art surfaces and materials, compiled by our in-house experts.
Acid-Free – is PH neutral (7 or higher) and is a requirement to ensure archival stability and preserve the artwork. Both cotton and linen are naturally acid-free and so it is necessary for any wood pulp used to make paper, to have a buffer to neutralize the lignin found in wood and bark.
Alkali – aqueous, water-soluble base with higher Ph than 7.
Alkali Paper – with alkaline paper (also called acid–free paper), the advantage is it has a much longer permanence (up to 200 years). Alkaline paper also has enhanced brightness, whiteness, and opacity compared to acid paper. The lack of acids in papers is also believed to be more environmentally sound.
Archival – this can vary according to criteria but generally in terms of paper, being acid-free is an expectation and that, no groundwood or unbleached pulp is used, not optical brighteners used to maximise the preservation of the artwork.
Bleeding – unwanted movement of colour through or across a surface.
Bristol board – layers of paper used to create a stiff board that would not need stretching or mounting. Paper was sent by the mills to Bristol to paste the layers together which is where the name came from.
Calcium carbonate – used in paper making as a buffer to neutralise paper pulp from acid.
Caliper – the minute thickness of paper, measured in thousandths of an inch or millimetres or micrometres.
Cartridge paper – a drawing paper usually ideal for pencil or charcoal its name comes from its original use of holding gunpowder. The surface texture can vary as can the weight.
Cellulose – a polymer found in plants basis used in papermaking.
Chassis – frame or stretcher for board, paper or canvas.
Cockling – the undulation caused in paper when wetted. It usually occurs with unsized or poorly sized papers.
Collage – often layers of paper, but also any material or objects where they are assembled and juxtaposed and attached to a surface.
Cotton rag – made from textiles, rags shredded, longer than the cotton linters so are stronger.
Cold Pressed (CP) – soft texture created by cold pressing of paper, known as NOT hot pressed.
Cross direction – the right angle to the direction of the machine rollers direction (MD) or grain direction, of a sheet of paper.
Deckle – the natural edge of the paper.
External sizing – in paper the layer of gelatine, animal or synthetic, on the surface of the paper to reduce cockling and enable the paint to sit on the surface. The paper is more likely to remain stable when working and allows the possibility of lifting colour, reworking, and removing unwanted areas, although this will be pending the staining property of the pigment, in which case, coating the surface with Winsor and Newton lifting preparation medium first is advised.
Felt side – The top side of the sheet which is on contact with the woollen carrier felts in production. Possesses more texture than the mould side which is the underside. The watermark will indicate which is the top of the paper. Also known as the good side or the right side.
Fourdrinier – Papermaking machines which make less expensive papers in industrial quantities. Refined pulp is sized and pressed through heated rollers to remove moisture evenly.
Forest Stewardship Council (FSC) – a rating used to certify international forest management standards.
Gelatin – A size used particularly for gilding but also for fine art papers.
Grain – texture of wood or canvas. As it pertains to paper, the grain refers to the direction in which most of the fibres lie. Grain is determined during the papermaking process, when fibres tend to align in one direction or the other.
Hard size: Possesses a high amount of internal and/or external sizing. Hard sized paper is likely to be more durable scrubbing and erasing the surface.
Hot Pressed (HP) – Hot pressed creating a smooth pressed paper surface by heat
Illustration Boards – drawing paper mounted to both sides of a heavyweight board to provide a rigid stiff surface to work on that does not need mounting or stretching.
Interface – a boundary between two surfaces.
Internal sizing – size added at the pulp stage to the vat to increase its hardness to make it more durable. Sizing is used in papermaking to improve the absorption and wear characteristics of the paper.
Laid – Paper lifted as a pulp from a mesh of laid and chain lines.
Lignin – polymers found in wood and bark in wood its acidity responsibility for the degradation and yellowing in cheap wood grade paper.
Linen rag paper – Made from a flax plant owing to the length of their fibres create a strong paper.
Linters – fibres offering strength and archival properties in making paper.
Mould made – Paper made on a cylinder mould machine a method closer to historical paper making where the fibres are mixed, and their random arrangement carefully lifted onto the mould to provide a stronger paper.
NOT– or CP cold pressed paper with a fine texture.
Pastel paper or board – is a textured surface to hold the pigment from the pastel.
PH – measurement of acidity and alkaline
PH 8-14 alkaline
pH 7 neutral
pH 1-6 acidic
Primer – surface preparation to aid adhesion of paint and serve as a protective layer to the support. Paper can be primed to accept a range of paint.
Printmaking paper – 100% cotton for strength and internally sized to withstand soaking for Intaglio and engraving print processes.
Rag content – rag paper is usually 100% cotton and refers to the fact that originally it was made from textile remnants.
Rough – textured paper that is not pressed
Size – a glue or gelatine to prepare canvas or reduce absorbency of paper and add strength
Suction Couch roll – helps remove excess water from the moving web of paper prior to the wet press section.
Surface sizing – external sizing, a method used to decrease absorbency of paper.
Wove – paper that is made against a woven metal mesh giving it the appearance of canvas not laid paper.