Lay the specimen to be tested on a clean flat surface with treated side on the top transparent films should be kept on the top of white paper for better visibility of marking spread the test fluid or ink from the felt tip of test pen lightly over an area of 7 cms² of the test specimen (i.e. strip of 7 cams x 1cms). Note time taken for continuous film on ink to break into droplets. And not peripheral shrinkage. (border shrinkage ).

Wetting is satisfactory or adequate ,when a continuous film of test fluid remains intact 3 seconds or more on the substrate to be tested .breaking of the ink film into droplets, in less than 3 seconds indicate a lack of wetting and a lower numbered test fluid to be tried. if the ink film remains intact for more than 3 seconds . The surface tension of this ink in dynes/cm “wetting tension” and these values are already marked on each of these pens/bottles.

Please note that observations of the liquid film behavior should be made in the center of the liquid film. Shrinkage of the liquid film on the edges of the applied ink does not necessarily indicate a lack of wetting. Breaking of liquid film into droplets within 2 seconds, indicate lack of wetting this is especially true for substrate having treatment level above - 40 dynes cams ²

Some experience with this will give excellent insight, to enable an accurate reading to be made. Extreme care must be ensure the film or substrate is not touched or contaminated in the area of lest.

It is recommended that when testing is done during the production, the test fluid or ink to be applied across the full web width.