The test inks are fluids of defined surface tension, which are available in bottles of 10, 100, 250 or 1000ml. The surface energy of a substrate is checked by simply applying the test ink to the surface. The accuracy of the measurement is 1mN/m.
The test inks are available in a range from 18.4 to 105 mN/m at almost any value. In the standard range between 28 and 56 mN/m there are different sets offered, consisting of 7 bottles of 10ml each, with a small brush for the application integrated into the cap.