Size test for paper by ink resistance (Hercules-type method), Test Method TAPPI/ANSI T 530 om-24

This method (1-3) measures the resistance of paper to permeation of an aqueous penetrant and is a useful general purpose test for degree of sizing.  It is applicable to most bleached, unbleached, and colored paper or boards which are surface sized and/or internally sized. It is not applicable to transparent or translucent papers (e.g., low basis weight papers where ink affects the reflection from the measured surface), colored papers that do not contrast with the green test ink, or papers having as part of their structure an effective water barrier such as polyethylene film.  An alternate method should be used for the direct comparison of papers which differ significantly in brightness, color, opacity, basis weight, or filler content, such as may exist among different grades of paper.  This limitation does not apply to normal production variations in these properties. It is a good test for comparing different samples of the same grade.