Coarse particles in printing inks reduce the efficiency of the dispersion process, requiring not only extra milling passes, but also frequent changes in pump filters. In printing processes, they may cause excessive wear to metal plates, piling or localized retention of ink on blankets and plates, and water balance problems. Coarse particles also reduce color strength and the gloss of printed matter.
This test method is suitable for quality control. The precision may be improved by the use of a specimen size larger than that prescribed.
Test results are sensitive to the type of washout solvent used. Strong solvents are to be avoided because they may dissolve large particles of resin in the ink vehicle.
1.1 This test method covers the determination of the weight concentration of coarse particles in printing ink dispersions by sieve retention.
1.2 This test method is applicable to printing inks, flushed pigments, and other pigment dispersions that contain particles larger than 45 μm. With proper choice of solvent, it is applicable both to paste and liquid inks.
Note 18212;This test method is similar in principle to Test Methods D185. For particles under 25 μm, see Test Method D1316.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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