Offset – The most common printing technique for publications printed in large volumes. In offset printing, an inked image is transferred (offset) from a printing plate to a rubber blanket, then impressed onto the surface of the paper. The aluminium printing plate is created beforehand using a photosensitive material. Offset printing incurs higher start-up costs, so it can be expensive for smaller print runs (<500 copies)—but the cost per book becomes exponentially cheaper as the edition increases in volume.
Digital – Digital printing refers to any process of printing directly from a digital file without the need to first create a printing plate. Because it has a faster and cheaper start-up, digital printing is better suited to smaller-scale print runs and print-on-demand projects. Digital printing can be split into two distinct types: Toner-based / Laser printing and Inkjet printing (see below).
Toner-based / laser – A method of digital printing that uses a fine powder called toner to create images and text on paper. Toner/laser printers are the kind commonly used in offices, and sometimes known as ‘Xerox’ printers or photocopiers. The impression is quite different from offset or inkjet printing in the way the printed image or text appears to sit on top of the paper almost as a separate veneer, rather than in the paper fibres.
Inkjet – A method of digital printing that uses tiny droplets of liquid ink. There is a wide variation in the quality and size of inkjet printers. It is used for high-quality photo printing, book printing (though much less often than toner-based), and cheap, small-scale home printing.
Risograph – A method of digital stencil printing that is useful for producing prints and publications in small to medium size editions (between 50–1000 copies). It is often described as functioning like a cross between a toner-based/laser printing and screen-printing, because it is fast and automated (similar to a photocopier), but prints in single ink layers through a stencil (similar to screen-printing). Screen-printing – An analogue printing technique whereby ink is pushed through a silkscreen which has a stenciled image on the surface. This stencil is created by coating the screen in a photosensitive emulsion and then exposing an image onto it using UV-light. Similar to risograph-printing, inks are printed in individual layers, with each layer requiring its own designated stencil. Screen-printing gives a very opaque ink impression and is often used for printing on textiles. It is not particularly economical for printing pages of a book, but is sometimes used for printing book covers when using a fabric or other non-paper material, or when an opaque print is desired.
Uncoated – Paper without any coating. Uncoated paper absorbs ink, meaning that depending on how rough and bulky the paper is, printed images and text will be rendered with softer edges.
Coated – Paper coated with a mixture of materials or a polymer to impart certain qualities to the paper, including weight, surface gloss, smoothness, or reduced ink absorbency. Coated papers are often categorised as either Glossy, Satin/Silk and Matte. With coated paper, the ink settles on the surface, meaning that images and text are usually sharply rendered.
Grammage: gsm, g2m, grs – Refers to the weight of a paper in units of grams per square meter.
Caliper: ɥm (microns) – The thickness of a sheet of paper measured in microns (1/1000 mm). It's not always the case that a heavier paper is thicker. It depends on the volume/bulk of a paper stock (see below).
Bulk or Volume – Calculated by dividing the thickness of paper by its grammage, to determine how dense the paper stock is. A higher bulk paper has more air in it and therefore lower density which leads to it being thicker without being heavier. Papers with a high bulk generally have a rough and open structure which absorbs more ink.
Grain Direction – Refers to the direction of fibers in a sheet of paper. In most cases, it is preferable to have the grain running parallel to the spine of the book, so that the sheets can be folded and bound cleanly. This allows for the book pages to flip easier, stay open, and lay flatter.
Long Grain (LG) or 'Langlopend (LL)' in Dutch – Sheets of paper with the grain running parallel to the longest side.
Short grain (SG) or 'Breedlopend (BL)' in Dutch – Sheets of paper with the grain running parallel to the shorter side.
Embossed or Textured paper – Embossing refers to pressing a relief design into paper. Common examples of embossing textures include: Linen, Laid, and Stucco.
Opacity – How opaque or translucent a paper is (and the degree to which the reverse side or following pages will show through). It is measured by percentage, with 100% being fully opaque.
Bond, Copier, Office, Plain paper – Various names for a smooth, generic white uncoated stock usually between 80-100gsm, typically the default paper used in photocopiers or ‘Xerox’ machines.
Wood-free – Paper made from chemically processed wood pulp where the lignin (the natural component that causes paper to yellow over time) is removed. The term can be misleading because it is still made from wood.
Wood-containing – Paper which retains the lignin, meaning this paper will yellow over time as it ages.
Acid-free – paper which has pH of 7.0 or greater which means there are no acidic substances, primarily lignin and chemical compounds in the paper fibres. Acid-free paper addresses the problem of preserving documents and artwork for long periods.
Archival paper – Archival paper is an especially permanent, durable acid-free paper. Archival paper is meant to be used for publications of high legal, historical, or significant value.
FSC – Forest Stewardship Council’ label - a certificate to show whether a paper stock is: ‘100% FSC’ - 100% from FSC managed forests; ‘FSC Recycled’ - made from 100% recycled materials; or ‘FSC Mix’ - made from a mixture of materials from FSC-certified forests, and recycled materials. https://fsc.org/en/what-the-fsc-labels-mean
Softcover / Paperback – General name for a type of book which does not have a hard cover. Softcover/paperback books are typically either glue-bound (also known as perfect/PUR-bound), or sewn in sections with the cover then glued to the spine.
Hardcover / Hardback / Case-bound – Books which have a hard cover, typically made from board which is then covered with a printed cloth, leather, or heavy paper. The pages are sewn together and glued onto a flexible spine between the boards allowing the pages to lay flat.
Section-sewn / Smyth-sewn / Thread-sewn – Type of binding used in both soft and hardcover books, whereby printed pages are folded into sections (signatures) which are then stitched together with thread. In the case of a softcover book, the spine is then attached to a cover material with glue.
Glue / Hotmelt (EVA) / Perfect (PUR) – Type of softcover bookbinding whereby the inside edge of pages (which are not folded in signatures) are roughened up using abrasives in order to expose paper fibers that will allow the glue to adhere more easily.
Cold Glue (PVA) – A bookbinding glue that can be used with section-sewn and glue-bound books. Cold (PVA) glue is more flexible when set and has the advantage of allowing a book to lay fully flat when open (depending on the choice of cover material).
Open-spine – A sewn binding method where no cover is glued to the spine, which leaves the thread, folded edges of the sections, and glue (if used) visible. In the context of an open-spine book, a 'cover' is constituted of either a piece of thick board or folded heavy paper which acts as the first and last sections of the sewn book-block.
Saddle-stitch – Printed sheets are folded together to form a single section then stapled, either with or without a cover sheet. This is commonly used for booklets and publications with lower page counts, although it can work just as well for thicker publications. With a saddle-stitch, the margins on the inner pages become narrower than the outer pages because they are being pushed outward at the fold then trimmed together — this is referred to as 'creep' and should be accounted for when preparing artwork, especially if the page count is high, or if the paper is particularly thick.
Singer-stitch – A similar method to saddle-stitch, where the publication is folded in a single section — however, instead of being stapled it is sewn with thread in a similar pattern to a seam on a piece of clothing. The word ‘Singer’ comes from the name of the sewing machine brand.
Pamphlet-stitch – A simple method of binding a single section using thread and a 3, 4, or 5-hole pattern.
Comb or Spiral binding – Holes are punched into a stack of loose sheets through which either a metal comb or spiral is inserted. With comb-binding, the stack of sheets is then placed into a machine which 'closes' the metal comb with a clamp.
Lamination – The process of applying a thin layer of plastic to paper or card sheets to enhance and protect the printed matter, often used on a book cover. The three most common types of lamination are: Gloss, Matte, and Soft-touch.
Foil stamping – A method of applying a metallic or pigmented foil onto a printed surface. This is often used on book covers as a special effect, such as for specific areas of text (like titles) or illustrations.
Spot-varnish – A clear varnish that can be applied in specific areas, rather than an all-over lamination.
Embossing / Debossing – The surface of the paper is stamped with a metal die to create a relief design. The depth of the embossing/debossing is dependent on the thickness of the paper or board.
Halftoning – The method of creating tonal imagery through the use of dots which vary in size and spacing to create a gradient effect. In an 'AM' or 'Screened' halftone, these dots are positioned on a grid, with the frequency of these lines of dots being referred to as 'Lines Per Inch’ (LPI). Typically, a greyscale or monotone image will use a grid that is angled at 45°, because this creates the least noticeable grid when the image is viewed from a distance. In a CMYK image, each ink layer is halftoned separately at a different angle, in such a way that the dots overlap as little as possible. Black (K) is usually set at 45°, Cyan at 15°, Magenta at 75°, and Yellow at 0°.
Bitmap or raster image – A digital image format that uses a grid of pixels which are assigned specific colour information. The word 'bitmap' is also sometimes used to refer to a black and white halftoned image.
Vector – A digital graphic format whereby points, lines, curves, colours, and gradients are defined through coordinates and a series of mathematical equations. Unlike bitmap/raster images which are made of pixels, vector graphics can be scaled to any size without loss of quality. Digital fonts are created through vectors.
Colour-profile – Colour information embedded in an image or pdf file. Different colour profiles are assigned depending on which inks are used — 'Greyscale' in the case of using only black ink, or 'CMYK' in the case of using all four process colours — as well as the type of paper that will be printed on, with both coated and uncoated papers having their own colour profiles. The reason for this is because different papers have different 'dot gain' (the expansion of each printed dot depending on how smooth or rough the paper surface is), which results in a darker/lighter image.
CMYK – An image or document that is composed of Cyan ('C'), Magenta ('M'), Yellow ('Y') and Black ('K') ink channels.
Multichannel – An image or document that is composed of multiple spot-colour channels, rather than CMYK. Examples of multichannel colour profiles can be found on Color Library.
RGB – An image or document intended for digital (screen) use, composed of Red, Green, and Blue light. Because RGB refers to light rather than ink, it is an 'additive' process which starts with black (no light), with colour being added through light.
Greyscale or Monotone – An image or document that is composed of only a single ink channel. In most cases this is black (Greyscale) but it can also be a single spot-colour (monotone).
Spot colour – A coloured ink which is not one of the four process inks (Cyan, Magenta, Yellow, or Black) and is often described through the Pantone colour Matching System (PMS).