The ability of paper to prevent ink from penetrating into its surface (in contrast to ink absorbency). Inks that produce the best result by drying via oxidation (as opposed to drying via absorption into the paper) require paper that has sufficiently low porosity. Too much ink holdout, however, can cause ink setoff. Inks achieve greater levels of gloss and better image quality when they dry on the surface of paper, rather than when they are absorbed. However, in some printing processes (such as high-speed web printing for newspapers), it is desirable to obtain rapid ink penetration and drying, a case where increased ink holdout is undesirable.
The degree of ink holdout is a function of porosity, as well as moisture content and a variety of other paper characteristics. (See Ink Absorbency and Paper and Papermaking: Paper Properties.)