The evaluation of the hair resistance can also be analyzed through another technique, sometimes even better correlated with what the consumer in fact experiments to reach the conclusion of fragile hair: breakage!
Talking this way, it may not seem to make sense, because the test of hair strands breakage through tension-deformation also breaks the strands. However, we performed the test and proved that, on an intact hair, the force necessary to pull the hair from the head is, approximately 70% lower than the force necessary to break the strand when being moved by traction.
A typical DSC curve (to learn more about the typical DSC curve click here) for a sample of virgin hair in which four different processes can be observed
The hair observed in the drain of the shower, after a house cleaning or even the brush used to untangle the hair normally, do no present hair bulb. Therefore, this hair was broken. Otherwise, the problem would be hair fall, not hair breakage.
The abrasion process experimented throughout the day by the consumers when passing the hands through the hair, drying the hair with a towel, combing or brushing the hair contribute for a removal of an essential structure to the hair fiber: the cuticles! The absence of cuticles makes it easier to weaken the inner part of the fiber and reduces the force necessary to break the strands. Contributing to hair breakage.
Thus, the analysis of resistance to breakage by abrasion represents more systematically that which is in fact experimented by the consumer on his daily routine. For that, we built the automatic brushing machine presented in the image above that simulates the brushing process in a salon, so one hair swatch can be brushed for a big number of times and the broken hair strands counted at the end of each cycle.
The comparison of this number of strands before and after the application of a certain product allows us to identify how much the product prevents hair breakage and how it improves hair resistance.