Stood-up Drop

With the innovative Stood-up Drop, KRÜSS contact angle instruments characterize surfaces in a matter of seconds based on the retraction behavior of dispensed drops of water. The method complements conventional contact angle methods and expands the possible applications of wetting measurement for testing material surfaces.

In almost 20 areas of application to date, the results correlate well with those of manual, analog, and user-dependent tests, e.g., the crosshatch test for the adhesion of coatings. The Stood-up Drop can thus reduce the number of time-consuming tests or even completely replace outdated, analog methods, such as testing surface activation with test inks.

The Stood-up Drop method measures the receding angle, i.e., the contact angle that occurs when a surface is dewetted. For technical surfaces, this contact angle often differs significantly from the more common advancing contact angle, which measures the degree of spreading of a liquid (wetting).

When measuring with the Stood-up Drop, a drop is dispensed onto the surface using high dynamic pressure. This drop initially spreads out flat and wets the surface, but then immediately retracts again due to surface tension. In a fraction of a second, a defined receding contact angle is established, which describes the dewetting of the surface. In technical materials, this contact angle often differs significantly from the previously more common advancing angle, which measures the degree of spreading of a liquid (wetting). Since the formation of interfaces in many industrial processes is also dynamic and accompanied by dewetting, the contact angle measured in this way accurately reflects such technical processes and is therefore particularly well suited for characterizing the interface process.

The measurement is performed with a single click based on defined parameters, independent of user decisions, thus ensuring reproducible results. Particular advantages for use in quality assurance lie in the non-destructive measurement and the use of pure water as the test liquid without any substances hazardous to health.

KRÜSS will present the Stood-up Drop at analytica 2026.