Acid Free Paper
Paper that does not contain any acid. Good for archival purposes. Precautions are taken during manufacture to eliminate any active acid that might be in the furnish, in order to increae the longevity of the paper (simetimes known as "long life paper")
A generic term given to woodfree coated papers which has traditionally referred to papers with a highly polished surface in the upper quality bracket. Today the term is less used because of the introduction of more categories in the sector.
The part of a printed image beyond the area to which the finished sheet will be cut.
The printing process where an image is applied to the substrate directly from a digital file rahter than using plates or film. Digital printing includes a variety of different technologies including inkjet, electrostatic, thermal transfer or laser.
Dots Per Inch (DPI)
Used usually in the context of semitone or process printing, which refers to the frequency of pirnt dots appearing. The greater the dpi, the finer the print.
Gloss can refer to the reflectivity of paper itself or to the printed result on it. Gloss of paper is measured by using a Gardner Glos Meter, which measures reflected light at an angle of 75o, and is expressed in Gardner gloss units - the higher the number, the glossier the paper surface
A flat surface printing process in which the non-image areas of the printing plate are made 'wettable' and the image areas are made to repel water whilst attracting the printing medium (ink)
PDF (Portable Document Format)
Electronic file format for pages including fonts, graphics and text
Also knows as the PMS, ie Pantone Matching System. This is an ink system where eight primary colours are mixed in defined ratios to acheive a specific colour.
The ability of a digital press or printer to individually personalise each sheet within a run. This can take the form of changing text, graphics or images, altering colours or typeface and personalising the content through variable data printing.
A pre-production print, made for the purpose of checking the accuracy of layout, type matter, tone and colour reproduction
Means of binding using wire for stitching
The surface smoothness of paper is measured by the Bendtsen smoothness test. The test measures the amount of air escaping between an annular ring and the material surface, and results are measure in ml/mim. Papers having a value higher than 50 are usually referred to as matt, below 50 as silk (sometime called satin or velvet)
Used to enable colour to be included in the print without mixing the primary colours