ASTM D4942-20 pdf free.Standard Test Methods for Water Pickup of Lithographic Printing Inks and Vehicles in aLaboratory Mixer.
The percent water pickup to the nearest wholenumber as the mean of the two determinations, the cumulativemixing time, and a description of the water used for testing (forexample,tap water，deionized water,or type of fountainsolution).
If rate of water pickup was determined,plot thepercent of water pickup versus the cumulative mixing time. The mean temperature，changes in pH,conductivity,appearance of the water,and the change inconsistency of the ink.
Test Method A-An interlaboratory study of single-point water pickup by Test Method A was conducted in which one operator in each of eleven laboratories tested in duplicateon each of two days three lithographic printing inks ranging in5-min water pickup from 50 to 65 %.One company was foundto be an outlier and was deleted from the analysis.The withinlaboratory pooled standard deviation was found to be 1.58 %absolute (millilitre of water per 100 grams of ink) at 9 degreesof freedom (df), and the between laboratories pooled standarddeviation was 7.1 % absolute at 30 df. Based on these standarddeviations, the following criteria should be used for judging theacceptability of results at the 95 % confidence level:Two results, cach the mean of tworuns obtained by one operator, should be considered suspect ifthey differ by more than 4.5 % absolute.Two results，each the mean oftwo runs obtained by operators in different laboratories, shouldbe considered suspect if they differ by more than 20 %absolute.
In an interlaboratory study of rate ofwater pickup by Test Method B, water pickup values at 2 1/2,5,7/ and 10 min were determined twice on one day by oneoperator in each of nine laboratories on six inks.The inksranged in water pickup from 40 to 52 % at 21/ min and from65 to 100 % at 10 min.After rejecting 12 out of 156 replicatedtest values as outliers，the within laboratory pooled standarddeviation was found to be 1.58 % absolute (grams of water per100 grams ink) with 97 df and the between laboratory standarddeviation 3.73 % absolute with 86 df. Based on these standarddeviations, the following criteria should be used for judging theacceptability of results at the 95 % confidence level:Repeatability cannot be determinedas both runs were conducted on the same day.Two water pickup curves，eachthe mean of two runs，obtained by operators in differentlaboratories should be considered suspect if they differ by morethan 10.5 % absolute.ASTM D4942 pdf download.