This definitive A-Z glossary of art paper terms has been designed to use as a companion when reading articles from our Paper Guide or any other art paper related articles online.
Glossary of Art Paper Terms
A
Abrasion Resistance
The level at which a paper can withstand continuous scratching or rubbing.
Acid Migration
When acid passes from an acidic material to a less acidic paper, such as exposure of atmospheric pollution or the acid found in mechanical pulp paper to acid free, archival paper. Acid can also migrate from acidic adhesives, boards, protective tissues, and cheap art supplies. Acid will cause lignins in the paper to break down, which can lead to the paper yellowing. In order to avoid this happening it is advised to only use acid free or pH neutral art materials, or apply a pH neutral isolation coat (such as acrylic matt medium) to materials known to be acidic prior to combining them with acid free papers.
Acid-free Paper
Paper that has a neutral pH (i.e. its value is 7 or higher). Paper can be naturally acid-free or neutralised in the manufacturing process. Cotton and linen papers are naturally acid-free, while wood-based papers will contain acidic lignins. These are neutralised with a buffer, most likely calcium carbonate, which protects the paper against acid migration.
Alkyl Ketene Dimer (or AKD)
A synthetic sizing agent commonly used in the manufacture of artist papers. It was introduced as a pH-neutral size in the 1960s. It is not derived from any animal products.
Alpha Cellulose
Alpha cellulose is the longest and strongest fibres used in plant based paper pulp. It is made up of multiple sugar molecules bonded together to form a chain. During the paper manufacturing process this chain is broken down, refined to remove undesirable elements (such as lignin, which is acidic) and then reformed to give strength to the finished sheet of paper. To optimise the strength of certain papers, alpha cellulose fibres from various sources are sometimes combined, for example wood and cotton. Chemical wood pulps have a high percentage of alpha cellulose but not as high as cotton, which is usually around 99%.
Archival
There is no universal standard of what ‘archival’ means in practice. But, generally, it refers to the fact that in addition to the paper being acid-free, the paper should be free from groundwood, unbleached pulp and not contain optical brightening agents. Alkaline buffers are often added to wood cellulose in order to counter any trace of acids remaining, in order to make it more archival.
B
Blocks
Pads of paper that have been glued on all four sides. Sheets can be worked on without them wrinkling as they become more saturated with watercolour, and once dry, sheets can be sliced off the pad with a craft knife.
Bone Folder
A dull edged smooth tool for creating folds and creases in paper crafts and book binding, made from animal bone or synthetic alternatives.
Bristol Board
A completely smooth or vellum texture surface paper that comprises at least two layers of paper (and often more) that have been glued together under pressure to form a robust drawing surface. It is especially suited to ink or dry media. So-called because in early European papermaking the ply sheets would be sent to Bristol, UK to be glued together. It is made of acid-free wood pulp.
Buckling
A term used to describe the uneven rippling of a paper caused when it has been over-saturated with liquid and then left to dry without influence from stretching or pressing under weighted boards.
Bursting Strength
A description of how much pressure a sheet of paper can withstand.
C
Calcium Carbonate
Calcium carbonate is often added to paper pulp in papermaking and acts as a buffer, neutralising the pH of the paper and protecting it from the harmful effects of acid. Calcium carbonate will help paper to maintain its archival properties. It also increases whiteness, however there is a limit to how much can be added to paper without it reducing the tear strength, burst strength and tensile strength of the paper.
Caliper
The thickness of a sheet of paper, measured in points, where one point equals a thousandth of an inch.
Cartridge Paper
The paper most commonly associated with drawing. It is so-called because it was used in the making of paper cartridges in the 16th century, holding the ammunition of gunpowder and bullets together for loading into hand-held firearms. Cartridge paper is most commonly made of woodfree cellulose and is primarily made for dry drawing media such as graphite and charcoal, however heavier cartridge papers (200 gsm+) will take some watercolour and ink with minimal buckling. It is available in a variety of weights and shades of white. Quality cartridge paper will have a slight texture to it – this is known as grain or tooth, and provides the resistance needed to hold marks in place. It also increases the depth of tonal range achievable in graphite or charcoal, as well as colour depth in pigmented dry media.
Cellulose
The key constituent of paper. It is a basic structural component found in many plants and is formed of long chains of glucose molecules. When cellulose fibres are beaten in water (during the preparation of paper pulp) some of the glucose molecules dissolve in the water. Hydrogen is added to rebond the fibres together, forming resilient sheets of paper when the pulp is dried.
Chain Lines
The lines on laid paper parallel with the grain of the paper.
Chemical Pulp
Pulp (wood/plant-based, with the exception of naturally acid-free cotton/linen) that has been treated to made it acid-free. Chemical pulping removes lignin from lignocellulose, leaving cellulose fibres suited to papermaking.
Chine Collé
A printing process in which a thin sheet of paper, usually washi, is printed on and at the same time mounted on a sturdier sheet as it goes through the printing press.
Cockling
A term used to describe the uneven rippling of a paper caused when it has been over-saturated with liquid and then left to dry without influence from stretching or pressing under weighted boards.
Cold Pressed, or NOT
Paper is made by pressing the sheet through cold metal rollers, and it has a slight texture to it. It is the most popular watercolour paper surface to work on because it is well adapted to many painting approaches. The paint will sink a little into the dimples on the surface of the paper, but it will also be sympathetic to some detailed work. Cold pressed paper tends to be more absorbent than hot pressed paper.
Cotton Rag Paper
Made from textile scraps, old fabric, and other post and pre-consumer waste like rope and nets.
Couch Roll
The equipment that helps remove excess water from the moving web of paper prior to the wet press section of a paper machine in paper manufacture.
Cross Direction
The opposite of the grain direction. Whereas the grain direction follows the direction the paper passes through the papermaking cylinders, the cross direction is ninety degrees to this; often the short edge of a full sheet of paper.
Cross Grain Fold
A fold that goes 90 degrees across the grain of a sheet of paper.
Cylinder Mould-Made
Cylinder mould-made paper can be seen as the ‘halfway’ point between handmade and Fourdrinier machine-made paper. The process makes more consistent paper than handmade paper, but is more sensitive to the characteristics of the material than industrial machines. Cylinder mould machines consist of a vat and a cylinder mould. The pulp mixture fills the vat and attaches itself to the moving cylinder, forming a very fine fibrous web over it. The web is then drained, and then pressed to varying degrees of pressure, either between sheets of felt to create a rough texture, or hot metal plates to achieve a very smooth surface. The randomly aligned ‘fibrous web’ gives excellent surface stability, an asset to all painting and printmaking processes.
D
Damp Pack
A stack of pre-soaked paper wrapped and weighted down to create evenly dampened sheets ready for printing.
Dandy Roll
In Fourdrinier paper manufacturing, the dandy roll is a light, open-structured unit covered with wire cloth and placed on the wire between suction boxes, resting lightly upon the wire and the surface of the sheet. Its function is to flatten the top surface of the sheet and improve the finish. The wires on the dandy roll impress on the paper to create the ‘laid’ lines in chain and laid paper, such as found in Ingres papers.
Deckle
The frame of the mould used to collect the wet pulp in order to form sheets in papermaking.
Deckle Edge
A deckle edge is a rough edge found on many handmade and cylinder mould-made papers. It is formed when some of the wet pulp goes beyond the frame of the mould (the deckle), forming an irregular thin edge. Handmade papers have four true deckle edges because the sheets are individually formed. Cylinder mouldmade papers have two true deckle edges – the edges that are cut from the roll are often torn to mimic a true deckle edge.
Dye
An ink colorant that is soluble in vehicle or solvent. It is less colourfast than pigment but is sometimes added to paper pulp in papermaking in order to tint the paper.
E
Emboss
When the paper moulds itself around the relief elements of the plate and retains the shape after drying.
EU Timber Regulation
Prohibits operators in Europe from placing illegally harvested timber and products derived from illegal timber on the EU market. ‘Legal’ timber is defined as timber produced in compliance with the laws of the country where it is harvested. The regulation applies to timber and a wide range of timber products, including pulp and paper.
European (ISO) ‘A’ Sizes
The dimensions of ‘A’ sizes of paper are determined by the ISO 216 paper system, which is used internationally (with some exceptions, including America and Canada). ‘A’ size papers have an aspect ratio of 1:1.414, the square root of 2. This means that if any sheet of ‘A’ sized paper is cut in two, the aspect ratio of the two halves will remain 1:1.414. The most common size is A4 (210 x 297mm), the dimensions of a standard letterhead. ‘B’ and ‘C’ sizes are also determined by the ISO 216 paper system and correspond to intermediate sizes for the ‘A’ series and envelope sizes respectively. See page 120 for a chart of A size dimensions.
External Size
Another term to describe surface sizing of paper, when size is applied to the formed sheets of paper to reduce the paper’s absorbency. Also sometimes referred to as Top or Tub Sizing. Gelatine and wheat starch are more common external sizing options, egg whites can also be used.
F
Felt Side
The upper side of the sheet, also known as the Top Side. It is more random in texture than the underside, known as the Mould Side (the side that is formed on the wire mesh side of the mould), which has a slightly more regular texture. It is called the Felt Side because it’s in contact with woollen carrier felts during production. If the paper has a watermark, when you hold it up to the light, the side on which the watermark is the right way round is the felt side. The Felt Side is often favoured as its surface texture is thought to be more aesthetically pleasing, however it is down to personal preference which side you paint on.
Fixative
A fixative is a liquid, similar to varnish, which is usually sprayed over a finished or in-progess dry media artwork to prevent smudging, or in the case of workable fixative, to give some tooth back to an artwork that has become slippery with built up graphite or coloured pencil. Fixatives are usually (although not always) alcohol based, hydrocarbon propelled and need to be used carefully in a well-ventilated area. Some fixatives contain UV fIltering agents to protect the work from fading.
Fourdrinier
Papermaking machines like Fourdrinier machines make the cheapest and most consistent paper. They are used to produce industrial quantities of paper for print media and stationary. Pulp is spread over a mesh conveyor belt which removes the water from the fibres with a vacuum. It is then pressed through large heated rollers to squeeze out even more moisture. Further series of rollers are also used to smooth the paper surface, add texture if necessary, and also to ensure uniform thickness throughout the sheet. The paper emerges from the machine in giant reels. The Fourdrinier machine was invented by Nicolas Louis Robert in 1799 and patented by the Fourdrinier brothers in 1806.
FSC
Forest Stewardship Council. An independent, international, environmentally and socially oriented forest certification organization. It trains, accredits and monitors third-party certifiers around the world and works to establish international forest management standards.
Full Imperial
The name of the traditional dimensions of a paper mould: 22 x 30”, and consequently the dimensions of a full standard sheet of watercolour paper. Paper sheets are often available cut into half or quarter sheets in addition to full imperial size sheets.
G
Gelatine
Gelatine is derived from collagen extracted from the skin, bones, and connective tissue of animals (it is a by-product of the meat and leather industries). Gelatine has many uses in food and cosmetics, as well as used as a surface sizing agent in some artist papers, adding strength.
Ginning
The process of extracting the cotton fibres, known as linters, from the cotton seeds, in order to use them in cotton rag papermaking.
Glazing
The building up of layers of contrasting colours on top of one another, in order to modify tone and colour appearance.
Grain Direction
The grain of a paper lines up with the direction the paper is travelling along the paper machine. With Fourdrinier-made papers, over 50% of the fibres align themselves with their lengths parallel to the mesh. It is easier to roll, fold or tear paper in its grain direction. Mould-made papers have more randomly distributed fibres, and as a result tend to be stronger and harder to tear.
Granulation
An aesthetic effect that adds texture and depth to a painting. It is the appearance of pigment settling in the valleys of the paper, which accentuates its texture. Rougher papers usually give more dramatic granulation as do watercolour paints that are made with coarser pigments.You may wish to work with a paper that encourages granulation, or if not it can be avoided by working with non-granulating paints on smooth paper.
Groundwood
Wood that has been mechanically ground to produce pulp. Fibres are shorter and possess a greater amount of lignins than chemically ground pulp. Its presence in artist papers is kept to a minimum in order to minimise acid-content and improve the longevity of the paper. ‘Wood-free paper’ actually means groundwood-free, yet despite this term wood-free papers can contain up to 10% mechanical pulp and 1% lignins.
GSM
The abbreviation for grams per square metre, gsm is the metric unit of weight for paper. In real terms it is the weight of a single piece of paper measuring one square metre. Also sometimes written as g/m².
H
Hard Sized
Paper that has a high amount of internal and/or external sizing. Hard sized paper tends to withstand more vigorous painting techniques, such as scrubbing and erasing.
Hot Pressed
The least textured surface; during production it is pressed between hot metal rollers. The absence of texture makes it suitable for fine detail. Hot pressed paper tends to be the least absorbent of all of the textures, and watery washes can sit on the surface for a long time. Beyond watercolour painting, hot pressed watercolour paper makes an excellent support for pen and ink drawing.
Hydrophobic Paper
Paper that repels water.
Hygroscopic Paper
Paper that absorbs water.
I
Illustration Board
A watercolour paper surface glued with pressure on to a cardboard backing. Illustration board is rigid, usually full or half imperial and can be cut to size. Suited to both fine art and illustration.
Ingres Paper
A laid finish paper of light to medium weight used for drawing.
Ink Holdout
When ink sits on the paper surface without being absorbed by it.
Intaglio
Print process where ink is embedded into engraved lines on a plate made of copper, aluminium or perspex, and transferred to paper by pressure. The opposite of relief printing, where ink is transferred to paper from the raised edges of a plate, most commonly lino or wood.
L
Laid Finish
The imprint of the screen pattern of an historical papermaker’s mould of widely spaced chain lines and closely spaced laid lines.This imprint is now replicated by a roller with wires on it that embosses the ribs into the fresh pulp of the sheet. Doing this at the pulp stage means there are thick and thin areas of paper, because some pulp is pushed off, which is a different effect to simply compressing the paper by embossing when it has dried. The laid effect creates a toothy grain of close lines on one side and a mottled surface on the reverse.
Laid Paper
The imprint of the wires of the dandy roll that impress the paper during manufacture to produce a watermark. The wires which produce the laid effect are situated parallel on the dandy roll and are not interwoven with the chain wires which appear along the grain of the paper.
Layout Pads
Primarily for marker and felt pen work. The paper is very thin, lightweight, semi-opaque, completely smooth and bright white. They are sized to resist marker pen bleed. The degree of transparency allows for elements of a drawing to be traced on to a new sheet as ideas are developed, however it is not sufficiently transparent to work as a comparable alternative to tracing paper.
Lifting
The process of removing paint that has been applied to paper, usually with a clean brush or sponge dipped in water. The amount of sizing in the paper is a significant determining factor of how easy it is to lift colour from a surface. The less sized and more absorbent the paper, the harder the paint will be to lift from it.
Lightfastness
Lightfastness refers to how resistant a material is to fading when exposed to light. No paper is wholly lightfast. In order to minimise the risk of fading paper should be stored in complete darkness, in a temperature and humidity controlled environment that is free of atmospheric pollution, which, unfortunately is not realistic in most circumstances. The most lightfast papers are made with a high quality pulp, without Optical Brightening Agents, and if they are coloured, contain pigments rather than dyes. The Blue Wool Scale (from 1= very poor to 8 = excellent) and ASTM ratings (V = very poor to I= excellent) are two measures of lightfastness. However both are limited in their accuracy, as they require subjective observation of when a shade has changed. Also the accelerated aging methods require extrapolation of results over a relatively huge timescale. This can often result in widely varying results for exactly the same paper. Generally, red and blue papers tend to be the least lightfast, while naturally off-white papers tend to be the best at keeping their colour.
Lignin
A acidic organic polymer which is naturally occurring in vascular plants and some algae, and is present in wood and wood bark, lending rigidity to plant structures and preventing premature rotting. When making artist paper with lignin cellulose from wood or vascular plants, lignin is removed because it can cause the paper to become brittle and yellow.
Linen Rag Paper
Made from the fibres of the flax plant. The length of these fibres is longer than wood cellulose or cotton fibre and as a result linen papers tend to be more robust and harder to tear.
Linters
Fine, silky fibres which stick to the seeds of the cotton plant after ginning – the process of separating the cotton fibres from the cotton seeds. Cotton paper can be made using cotton linters.
Lithography
A print process that relies on the repellant nature of oil and water. An image is created using oil based material on to a stone or sheet of metal, lightly coated with water and then inked with a roller before an impression is taken on to paper.
M
Marker Pad
This paper is sized in order to resist marker pen bleed. It is bright white and completely smooth. Also well suited to graphite, coloured pencil, wax crayons and other ink based media.
Matt Medium
A clear acrylic based fluid medium that can be used to coat paper to prepare it as a surface for oil and acrylic painting.
Mould Side
The underside of the sheet in production, the mould side is the side of the paper that is formed on the wire mesh side of the mould. It has a slightly more regular texture than the other side, known as the felt side. The felt side is usually the preferred side on which to paint, although it is a question of individual preference.
N
Newsprint
Thin, light grey paper that is internally and surface sized, but designed for printing gravure on reels. Its acid content causes it to yellow easily, especially if kept in natural daylight. Because of its low cost, newsprint is often favoured for quick disposable sketches and initial proofs in printmaking.
NOT
Another term for cold pressed paper. It is made by pressing the sheet through cold metal rollers, and it has a slight texture to it. It is the most popular watercolour paper surface to work on because it is well adapted to many painting approaches. The paint will sink a little into the dimples on the surface of the paper, but it will also be sympathetic to some detailed work. Cold pressed paper tends to be more ab-sorbent than hot pressed paper.
O
Optical Brighteners (OBAs)
Optical Brightening Agents (or OBAs) are additives that manufacturers may use to make their paper look whiter. Optical brightening agents will fade over time with exposure to UV light, so many manufacturers of archival quality artist papers do not use them.
P
Paper Fingers
Little folded pieces of paper with which you pick up clean sheets of paper to avoid inky fingermarks. Used mainly when printmaking.
Papyrus
A material similar to thick paper that was used in Egypt at least as far back as the First Dynasty. Made from the pith of the papyrus plant, it was used to make items such as reed boats, mats, rope, sandals, and baskets. Often thought to be a precursor to modern paper.
pH
A value indicates a materials alkalinity or acidity. Archival paper will be neutral – alkaline; on the pH scale it will measure between 7.5 – 9.5.
Picking
The ability of tacky ink to pull up fibres from the surface of the paper.
Pulp
A plant-based dry matter, comprising carbohydrate polymers and lignin. It is prepared by chemically or mechanically separating cellulose fibres from wood, cotton, linen, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw material used in papermaking as well as other industrial grade paper products.
R
Rag Paper
Another term for Cotton Rag paper.
Ream
500 sheets of paper, or 516 when referring to a printer’s ream.
Relief Print
Print process where ink is transferred to paper from the raised edges of a plate, most commonly a carved piece of wood or lino.
Right Side
Another term to describe the felt side of a sheet of paper, although which side you paint on is a matter of personal preference.
Rough
The roughest texture paper available. It is pressed between sheets of textured felt during the drying process. The heavier texture means that granulating (irregular settling of pigment particles) effects are enhanced. This paper surface is not recommended for detailed work and is more suited to bolder, more expressive painting techniques.
S
Size Tub
The vessel that contains the sizing ingredient when surface sizing paper.
Sizing
Sizing is used during the manufacture of paper to control its absorbency (internal sizing) and add strength (surface sizing). Papers can be sized internally, with size added to the paper pulp during production. Most hand papermakers use a synthetic chemical called alkyl ketene dimer, which protects and coats each fibre. Sizing can also be applied externally (also called surface or tub sizing), after the paper has been formed, pressed, and dried. Gelatine and wheat starch are more common external sizing options, although egg whites can also be used. The method and amount of sizing depends on what the paper is intended to be used for.
Starch
Derived from wheat, rice, and other plants. It is one of the oldest materials for sizing paper, and has been recorded in use by Chinese papermakers as early as A.D. 768. Starch is still used today as a sizing agent for some papers.
Stump
A stick of compressed paper with a pencil like point at both ends, ideal for blending coloured pencil or pastel marks or applying dry powdered media with.
Sulphite
A chemical method of producing paper pulp from wood using high heat and sulfur dioxide. The sulfite process was first patented in 1867, but not in wide use until improvements were made in the 1870s-1880s. To produce pulp, wood chips are cooked in a solution of sulfur dioxide dissolved in an alkaline solution (typically a calcium base). The cooking or steaming process produces bisulfite and then monosulfite, which dissolve lignin and hemicellulose. This method produces a bleachable pulp with a high yield, low cost, and high brightness.
T
Tear Bar
A heavy metal straight edge used for tearing down sheets of paper.
Tonking
A method of correcting an oil painting that has become overloaded with wet paint or oil. Newsprint or kitchen towel is laid over an area of wet oil paint and rubbed down. When lifted it removes excess paint and oil. The benefit to this method contrasted with scraping or wiping the paint away is that you do not lose the composition, a thinner version of it remains. It was named after Henry Tonks, an English painter influenced by the French Impressionists, who taught the technique at the Slade School of Art from 1893 to 1930.
Tooth
A word used to describe the texure of paper. Paper with a heavy tooth will be heavily textured, and have a greater ability to hold drawn marks in place. Tooth increases the degree of friction between surface and drawing or painting material, causing more colour to the applied to the surface. Consequently heavy toothed papers tend to have the ability to show a wider tonal range as well as deeper colour saturation. Papers with less tooth are suited to finer detail and crisp drawn lines.
Torn Edge
The creation of an edge by tearing the paper as opposed to cutting. A torn edge can compliment a true deckle, often found on two edges of a sheet of handmade paper.
Tortillion
A tortillion is a hollow tube of tightly-rolled paper which can be used to blend charcoal, pastel or pencil drawings. It is used in much the same way as a paper stump, but is slightly sharper at the tip and is therefore less suitable for blending large areas.
True Deckle
The actual deckle formed as the paper slurry slips between mould and deckle, this is as opposed to a torn edge that can mimic a deckle.
Tub Size
The paper sheet is passed through a vat of size after the sheet has formed, in printmaking usually a soft surface size to assist ink holdout, or in watercolour to prevent paint from sinking into the paper too readily.
U
UV Resistance
The exposure of paper to ultraviolet light can cause lignins to break down to form acid, which can either bleach or darken the appearance of the paper. No paper is entirely lightfast and so in order to protect paper from the harmful effects of UV light it is advisable to keep it behind UV resistant glass, or away from sunlight, in a portfolio for example.
V
Vellum Surface and Vellum Finish
Distinguished from vellum paper which is an historic translucent paper made of calfskin or its modern vegetable vellum replacement, a vellum finish is a texture on the surface of paper to give it a moderate tooth and a subtle, even surface of peaks and valleys similar to the fine texture of an eggshell. The term ‘vellum surface’ is sometimes used by pastel paper makers to describe a more deeply dimpled surface.
Virgin Fibre
Fibre derived from a source not previously used for papermaking; not recycled.
W
Waterleaf
A paper without any sizing, usually for use with oil based printing inks.
Watermark
A watermark is an image that identifies the manufacturer of the paper. It is created by changes in the thickness of the paper, light being able to pass through thinner areas, so that when a paper with a watermark is held to light, the image can be seen. Watermarks are made during the sheet formation process.
Wet Strength
The description of how much strength a paper retains when completely soaked with water.
Wood-free Paper
Paper made from a wood-based chemical pulp rather than mechanical pulp, which is not as susceptible to yellowing as paper containing mechanical pulp. Confusingly wood-free is an abbreviation of ‘groundwood-free’, and is a term only used for wood pulp paper.
Wove Finish
A completely smooth paper surface.
Y
Yupo
Yupo is a bright white synthetic paper, free from animal products, plant fibres, and 100% recyclable. It is made from heated poly-propylene pellets, extruded to form the layers of paper and then stretched using a cross direction technique called biaxial orientation. This process means that Yupo paper is exceptionally strong, tear-resistant and has an incredibly smooth surface. There is no need to stretch, soak or prepare synthetic paper in any way before working as it is naturally buckle-free and remains perfectly flat. The smooth non-porous surface can be used with a combination of media, including watercolour, gouache, alcohol ink, acrylic paint, monotype, offset printing, debossing, oil pastel, graphite and silkscreen and crayon.
