Like most industries, the print world contains a whole language of acronyms, phrases and terms that can confuse even the most seasoned print manager. Below is a reference guide containing numerous printing definitions you’re likely to come across when dealing with the print industry.
Are the premium quality coated ranges, with high quality, woodfree pulp and double or triple blade coating to form even surfaces with superior dimensional stability.
Binding and stitching
There are several ways to bind and stitch documents and detailed below are the most common:
Bitmapping or pixilating
In terms of troubleshooting, this generally refers to an image of poor quality resolution, where the image has not been constructed using the correct number of pixels and as a result the image breaks down into blocks/areas of colour.
Print area outside trim marks – usually a minimum of 3mm
Defined by VAT as paper that is over and including 180gsm
This is measured by and expressed in microns. (1000mic=1 millimeter)
Although more expensive, this method is similar to perfect binding, though it is stronger and more durable. The sections are scored with a knife along the spine and when the glue is applied this penetrates the grooves, adding extra strength. NOTE: A minimum 3mm spine is required for this method of binding.
A paper finishing machine/process which involves feeding reels through high pressure rollers to smooth the surface. Gloss papers are the most calendared and thus, thinnest.
A strip of tones and solids used to check printing quality throughout the process as a negative and positive, proof or printed sheet.
Cast Coated Paper
Ultra high gloss surface manufactured by a heated mirror surfaced drum, (can be double/single sided).
The initials indicating the printer’s primary colours – cyan, magenta yellow and black.
Paper which has been coated with a mixture of china clay and or calcium carbonate combined with starch and latex binder.
These are differentiated by their surface and printing qualities.
CTP (Computer to plate)
Where plates are exposed rather than film, eliminating several pre-press production stages. This does away with distortion from films and finer dots and line images can be achieved.
A coloured strip on the edge of the sheet which enables the printer to check by eye or instrument the printing characteristics of the ink.
When paper is folded with each fold in the opposite direction to the one before it.
These are produced using light sensitive film which becomes tacky upon exposure. Coloured powder is then dusted over the film and sticks to the image area. For each colour a separate film is used and built up in layers. ie. CMYK + specially mixed Pantone(TM) colours.
where an image or part of an image is “cut out” from its original background once scanned.
The drawn line showing the shape that the document should be cut post printing. Also used to show where creasing and folding occurs.
Relief printing or stamping in which dies are used to raise the surface of the paper around the characters.
The name given to the increase of size in halftone dot as it is transferred from film to plate to printed sheet. This change is called ‘dot gain percentage’ and will always be a plus factor. The press dot gain must be anticipated at reprographic stage.
A form is made consisting of knives, blunt for creasing and sharp for cutting. The die is placed in a converted letterpress (printing machine) and used to cut out and crease the required item e.g. folder etc.
A halftone created by two/three/four screens, plates and colours. These create a richer, deeper and more contrasting image than a one colour/mono tone.
Relief printing or stamping in which dies are used to raise characters above the surface of the paper.
EPS: Encapsulated Postscript
These files contain all the necessary information required to rip the file to print. However the information can only be read and cannot be altered or added to in any way unless the user has the relevant software.
Where an extremely fine sheet of coloured film is applied to a blocked or embossed design.
The most common way to finish a job is to fold the sheet prior to binding or trimming to size. At this stage all line-ups and read acrosses will be created.
A specific size and style of type within a type family. A typeface is the collection of a family of fonts. For example Helvetica is a typeface and 8 Point Helvetica Bold is a font.
The dispersion of fibres within a printed sheet. The uniformity of the fibres affects the even distribution of ink (poor formation can result in ink mottle).
A term used to describe a sheet of paper that has been printed on one side only then folded to create a 4pp that is bound along the open edge to form a 2pp.
Where a sheet has two folds that meet together.
Has the most reflective, smooth surface which makes results in maximum ink lift. It is also generally the fastest drying.
The direction that the fibres lie in a sheet of paper, (ie; short grain on short edge of sheet etc). Converting parallel to the grain affords a smoother fold than working against the grain (and minimises cracking on coated paper).
The reproduction of a continuous tone image (eg: photograph/transparency)
Laser proofs of final file.
Printing defect caused by a dust particle holding the paper or board away from the printing surface.
the application of varnish on the last unit/a single pass through the press.
Iris proof or digital proof
A digital proof reproduces a halftone effect digitally without the need of film. ‘Iris’ is a brand of digital proof.
Is a compressed file format and should not be used to output for printing. Quite often a JPEG image may appear fine on screen but when ripped to film, certain components of information are missing and when printed the image is different (often the colour is lost).
A process of applying a transparent plastic film to the surface of a printed sheet. This is used to make the final sheet more durable and less likely to mark or scratch. Laminates come in different types of finishes – Matt, Gloss and Silk, the latter being the most durable. There are also different makes of laminates eg: OPP and Acetate.
A process in which printing and non-printing surfaces are on the same plane and the substrate makes contact with the whole surface. The printing part of the surface is treated to receive and transmit ink to the paper via a blanket, the non-printing surface is treated to attract water and thus rejects the ink from the ink roller which touches the whole surface of the sheet.
Similar to saddle stitching, however the wires contain a loop which enables the final document to be stored in a ring binder.
Not to be confused with wet proofs, machine proofs are the most accurate and most expensive type of proof. Called machine proofs because they are actually produced on the final printing press. Produced in the same way as the final document
Metallic & Fluorescent inks
These inks contain special colourants which deteriorate on prolonged storage over 12 months. Fluorescent inks may need to double or even triple pass to achieve the desired effect.
Attachment of plates, adjustment of blankets, setting of registration, balancing of ink colours and other press preparation prior to print run.
Has a duller sometimes less smooth surface, thus producing a “flatter” image/colour with minimal glare.
An uneven impression especially in flat areas. It is usually caused by too much pressure or unsuitable paper or ink.
The application of a wet varnish or ink colour onto a layer of dried ink that has been run previously in a pass through the press.
Standard, multi-purpose grades: generally available in a broad range of sheet sizes in paper weights, with limited/no board range. Can be used for stationery as well as leaflet and brochure work.
A lithographic method of printing in which the ink is first transferred from the plate to an offset (rubber) blanket and then onto the stock.
The quantity of unit production, work delivered into the customer above the net amount ordered and also an allowance to cover wastage.
Numbered pages throughout the document. Remember: generally all books are made up in sections of 4. Unless there are fold-outs the number of pages within a book must be divisible by that figure.
Is an international printing colour system which provides an accurate method of matching and controlling colours.
Part-mechanical Paper/ Commodity Papers
Are cheaper (coated) grades which include the woodchip waste in the pulp. These can often be seen as grey patches in the sheet and this can form a less even printing surface.
A process whereby a sheet is printed on both sides at the same time.
Folded sections are collated and glued along the spine and then inserted into a cover which holds the pages together. Care must be taken with perfect bound books because constant use can result in a broken spine and pages can start to pull out. NOTE: A minimum of 3mm spine width is required for this method of binding.
Once ripped, there are essentially four main ways to proof a job.
A mixture of cellulose fibres and water, which is the basic ingredient for paper.
Often manufactured at the same mills as offset grades, these boards have a high weight to bulk ratio, making them particularly cost effective for mailing.
As perfect binding, but with a stronger (PUR) glue. Note: PUR glue requires 24 hours to cure/set
This can contain as little as 10% post-consumer waste (by The Stationery Office Guidelines). Recycled paper is assessed by its content values of virgin fibre and broke, pre-consumer waste and post-consumer waste.
Marked place in the same relative position on sets of printing plates so that when the marks are superimposed in printing the image falls into the correct position/is “in fit”.
The resolution of a reproduction is determined by how many pixels are used digitally to recreate the image. The greater the number of pixels, the higher the resolution. When printing it is important that all digital image files are of the correct resolution.
This is defined by dots per inch (dpi). As a rule of thumb:
• Where possible, images should be placed within a digital document at 100% size.
• Low resolution images tend to be between 72dpi – 120dpi at 100%
• High resolution images should be at least 300dpi at 100%
RIP: Acronym for Raster Image Processor. Raster is the most common method used by image/plate setters to “draw” images.
When each fold is in the same direction as the preceding one.
Generally the car of choice for those working in the reprographics industry during the 90’s, usually finished in British Racing Green. A 600 series was used for deliveries of film and plates, whilst the managing director would typically drive an 827 sterling.
The marking of the underside of a printed sheet by the transfer of ink from the sheet on top of which it lays.
Squared-up: where the scanned image is to be reproduced with a square border.
Much like dots per inch, screen rulings are used to break down the image into tone and halftone using dots. Screen rulings are measured in lines per inch or ‘lpi’. The higher the number of lines per inch, the finer the quality of print. Here is a rough guide to follow:
• 80lpi – 100lpi – newspapers
• 150lpi – flexography
• 133lpi for screen printing
• 150-200lpi- for general lithography
• 250lpi – 300lpi – for fine art
A printing machine into which sheets are fed singly.
Images are imposed, printed on one side with one set of plates and then with a second set of plates for the reverse. (To back up)
A tint of a secondary colour run beneath a solid to make a richer final effect.
Side stitching or stab stitching
Used for certain kinds of books or pads. The folded sections are gathered one on top of the other and a wire stitch is forced through from front to back. The wire stitch is usually about 3mm in from the spine.
Sitting in between these two has the advantages of superior ink lift to matt stock and reduced glare.
Any area of colour that is not designated to print CMYK – i.e. a Pantone(TM) colour.
Stationery/Office Printing definitions
Designated and manufactured for laser /desktop printing or photocopying. Can also include matching envelope ranges.
This is the strongest and most hard wearing of this type of finishing. The sections are held together by a continuous sewn thread that runs between all section. NOTE: A minimum 3mm spine is required for this method of binding.
Text & Cover
Often (though not exclusively) uncoated paper which is aimed for high quality, demanding brochure work. Made with superior (and sometimes unusual eg: tobacco, cotton, even beer mat!) pulps. They are usually produced in smaller, more specialised mills, with machines run at slower speeds to create superior printability.
The process where freshly printed sheets are dusted with resinous powder which forms a raised surface when fused with heat.
Made from pulp containing sulphite which lends the paper its transparency. These papers are non-porous, so fully oxidising litho inks must be used.
Where two or more colours abut and spread into each other. Used to avoid a white line due to bad fit or misregister. Problems here are generally due to paper/film stretch or errors in imagesetting
Tagged image file format – this is a more versatile file which can be altered and extended. Most tiff files are of a bitmapped format.
Manufactured with two continuous forming wires (joined together to the underside with the paper at the centre), resulting in less variation in side-to-side evenness.
Two wire saddle stitching
Is usually the cheapest method of binding publications. The document is opened over a saddle shaped support under a mechanical head and a wire stitch (staple) is forced through the spine. As a general rule, the maximum size is A3 and the minimum size A6 (unless finished two or more up and then guillotine trimmed down individually).
Can be graded/are generally sold by the following classifications.
Not to be confused with gloss (machine) varnish. This has a very high gloss finish and is applied by a roller in a thick layer and then dried very quickly under UV lights to give it its high finish.
To apply oil, synthetic, spirit, cellulose or water varnish to printed matter to enhance its appearance or to increase its durability. Spot varnishing is where a plate is created to selectively varnish specific areas.
Paper in the UK is generally sold in terms of its weight (in grammes) per set area (square meter). this is expressed/abbreviated as “gsm”.
Wet proofs (flat bed proofs)
Produced from the final metal plates and gives a truer effect, usually on the required stock. Produced on a one colour flat bed proofing press. Each colour is printed one pass at a time. On a proofing press the ink rollers run over the flat plate.
Work and tumble
When the image is printed in its entirety on both sides of a sheet by using a different gripper edge on the back up, than on the first printed side.
Work and turn
When the image is printed in its entirety (ie: its front and back) on both sides of a sheet using the same gripper edge/set of plates.
Printing definitions not included in our guide? Let us know. We’ll happily answer any technical questions you have and add the definition to our knowledge guide.