Four-color printing

Vierfarbendruck, m. four-color printing. Vier-flach, n., -flachner, m. tetrahedron, vierflachig, a. fom-faced, tetrahedral. 

The pigment industry produces primarily the more transparent diarylide yellow pigment types. This has its advantages, particularly in the field of printing inks, since yellow is printed as the last color in three or four color printing (Sec. 1.8.1.1). Highly transparent varieties are almost exclusively resinated and are often easy to disperse. 

P.Y.12 has a medium yellow hue, which is used to a large extent in letterpress and offset printing inks as the yellow component in three and four color printing. To adjust P.Y.12 to the standard yellow of the European standard (Sec. 1.8.1.1), the hue may be shaded with traces of a redder component, such as one of the orange pigments P.O.13 or 34. No such shading is necessary for P.Y.12 to match the yellow on the Kodak scale. 

P.R.146 is somewhat yellower than P.R.57 1 it therefore fails to match the standard magenta for three and four color printing. However, P.R.146 prints have the advantage of good application performance (Sec. 1.6.2.3), corresponding to the above-mentioned solvent fastnesses. 

The pigment affords very bluish shades of red, which are too much on the blue side to match the standard magenta for three and four color printing. The commercially available type is considerably opaque but not very lightfast compared to other Naphthol AS pigments. 1/3 SD letterpress proof prints, for instance, equal only step 3 1 on the Blue Scale for lightfastness while 1/25 SD specimens match step 3. 

Its main market was in printing inks, where it was used in three and four color printing. P.R.222 is heat stable up to 180°C, which made it a suitable candidate for... 

Incorporated in printing inks, phase-stabilized a-Copper Phthalocyanine Blue, like nonstabilized types, is too reddish to be employed as a process color for three and four color printing. It is used, however, to a considerable extent in all types of printing inks for special and packaging purposes. The prints are stable to common organic solvents and exhibit perfect fastness properties in special application (Sec. 1.6.2.3). Metal deco prints withstand up to 200°C for 10 minutes or 170 to 180°C for 30 minutes. They may safely be sterilized. 

Other fastness properties in application largely equal those of P.B.15 1. In printing inks, P.B.15 2 is employed mostly in special gravure and flexographic inks. This is an area in which lack of fastness to overcoating is frequently of no consequence. P.B.15 2, like other a-Copper Phthalocyanine Blue types, is too reddish to be used as a standard cyan for three or four color printing. 

The printing inks industry uses P.B.15 3 especially as a blue component on different color scales for three and four color printing. The pigment corresponds to the CIE12-66 standard shade of cyan on the European Color Scale for offset and letterpress prints (Sec. 1.8.1.1). 

P.B.9 matches the standard cyan for three and four color printing (Sec. 1.8.1.1). The pigment is continually losing significance as it is being displaced by the similarly shaded [3-modification of Copper Phthalocyanine Blue. The latter offers a number of applicational and economical advantages. P.B.9 continues to be used in mass colored paper, textile printing, and in colored pencils. 

P.R.81 is used especially in three and four color printing and lends itself to various printing processes, therefore pigments of this type are referred to as Process Red in the USA. Used as a colorant for NC-based printing inks, SM types of P.R.81 may present problems as they are dispersed with steel balls or stored in steel containers as well as at elevated temperature. Catalytic decomposition of the binder and damage to the pigment may induce a color shift and increase the viscosity. 

P.R.169 parallels the P.R.81 types in terms of shade and fastness properties. Thus, P.R.169 types are equally suited to letterpress and offset printing inks, where they provide the standard purple red for three and four color printing in accordance with the so-called DIN scale (Sec. 1.8.1.1). Moreover, P.R.169 is frequently used for toluene-based publication gravure printing inks, where it is sometimes applied in combination with P.R.57 1. A number of grades, however, are not as fast to toluene as comparable P.R.81 varieties. One of the major fields of application for P.R.169 is in aqueous flexographic printing inks. 

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