Let us, however, remember that the most important tool in the colour management process is not a spectrophotometer but... a telephone. Good communication, held among the customer, the designer and the printing house at an early stage of task planning, will ensure that misunderstandings and numerous problems are avoided after production is triggered, when the problems may then turn out to be rather expensive. Therefore, at the earliest opportunity, we head to the printing house for approval of our project and try to pal up with the printer.
Glossary of terms:
• coated paper – paper enriched by a coating layer which consists of a pigment-adhesive mixture.
• woodfree paper – paper without lignin, produced mainly from chemical pulps.
• wood-containing paper – paper with lignin content, produced mainly from mechanical pulps.
• mechanical pulps – fibre pulps, obtained by mechanical wood defibering, semi-product for paper production.
• chemical pulps – fibre pulps, obtained by wood delignification, i.e. chemical solution and removal of the lignin majority. Another term is a cellulose. Semi-product for paper production.
• surface-sizing of paper – application of adhesive layer on the paper web. Modified starch-based adhesives are mainly used. Surface-sizing increases paper resistance to abrasion, reduces the absorbency of ink and decreases dusting tendency.
• paper grammage – paper weight (expressed in grams) of one square meter of a paper product.
• paper volume – the paper thickness (expressed in micrometres or microns) to paper grammage (in g/m²) ratio. Also called bulk. Extremely smooth, glazed, uncoated papers present the bulk of 1.1. High bulk papers may even reach the volume of 2.0.
• paper opacity – defines the level of absorption of light as it passes through the paper.
• solid – a surface printed with single, non-screened colour.
• screening – the technique that is used in printing to simulate continuous-tone images such as photographs using tiny elements: dots or lines.
• amplitude modulation screen (AM screen) – a screen, in which tonal differentiation results from size changes of regularly laid dots. Other terms: traditional screen, conventional screen.
• screen dot – an element of screened image. It is a point which is covered with ink during printing.
• screen ruling – in AM screen, it defines the number of rows of dots (or lines), configured in parallel to one another, per length unit. The screen ruling is expressed in lines per inch – lpi or – more rarely – in lines per centimetre.
• CMYK model colours – process inks in four-colour printing: Cyan, Magenta, Yellow and Black (Key colour). Combined together on a printed image, they provide the final colour.
• maximum ink coverage – a parameter which determines the maximum volumes of all CMYK inks, which can be used for printing In offset printing. There is 0 - 100% coverage for each of the four CMYK colours. Thus theoretically – we can obtain a maximum value of 400%. In other words: Total Ink Limit, Total Ink Coverage.
• ink setoff – printing defect characterized by the transfer of wet ink to the reverse side of the sheet lying on top of it in the press delivery tray. In extremal cases, it may lead to sticking of sheets in stack.