The aluminum in antiperspirants create so-called “plugs”, which block the exits of the sweat glands. This leads to a reduced sweat secretion and consequently to a decrease in sweat-related smell. The efficacy study of such products is often carried out with a gravimetric method in which the sweat is absorbed using cotton pads and weighed after a defined sweating time. The comparison to the baseline values (empty weight of the pads) then allows conclusions on the efficacy.
Plugs in sweat glands
Partly Negative Sweat Reduction
Most aluminum-free antiperspirants do not work in the sweat gland, but on the skin. They often contain so-called superabsorbents, which are like a film on the skin and absorb sweat. Our research has shown that measuring efficacy by means of pads is inappropriate and sometimes produces negative sweat reduction results. A supposed cause is that pads not only absorb sweat, but also the test product.
As such, the challenge for our developers was to implement a methodology that does not interfere with the application of the test product. Since sweat consists of 99% water, it makes sense to carry out the determination of the efficacy of aluminum-free antiperspirants on the basis of the parameter ‘moisture’. This task was mastered very successfully in a master thesis entitled “Evaluation of methods for determining the efficacy of aluminum free antiperspirants”, which was awarded by the SEPAWA.
By means of ‘Capacitive Contact Imaging’ moisture can actually be depicted. The changes in sweat secretion are measured in a defined area. When measuring, the probe produces an occlusion effect, which enriches the sweat under the probe. The measurement is carried out simultaneously for the treated and untreated area. This optimizes standardization and comparability. In addition to an extremely differentiated and pixel-precise analysis option, the visualization of sweat formation in the video (see below) is another feature of the methodology.
For any questions you may have please do not hesitate to get in touch with Gunja Springmann.