432 JOURNAL OF COSMETIC SCIENCE
slower tendency for breakage. This is easily attained through use of conventional conditioner
products that coat the hair with a thin lubricating deposit comprised from fatty alcohols and
quaternium ammonium surfactants. In our industry, so-called repeated grooming experiments
are frequently used to demonstrate this occurrence whereby hair tresses are repeatedly
brushed with the periodic counting of broken fibers.25
In accordance with this theory, these experiments demonstrate sizable benefits as the result
of such treatments and represent tangible consumer benefits. As per a previous discourse,
if a consumer experiences breakage, there is the perception that their hair is “weak” and
“damaged ” however, if this situation is alleviated, the consumer perception is that the
hair has been “strengthened” and “repaired.” Accordingly, such language is commonplace
on products – but it should be remembered that these propositions relate to “consumer
language” and not the strict definitions associated with “technical language.”
To summarize, fatigue testing outcomes teach that “strength” and “breakage” are not the
same thing. Our industry has historically used standard tensile experiments to equate a
fundamental technical strength however, fatigue testing yields differing outcomes and
highlights the contribution of previously unrecognized factors. For example, a conventional
conditioner product has no effect on the tensile strength of individual hair fibers but can
produce sizable mediation of breakage.
SPLIT ENDS
The internal structure of hair is not unlike that of a rope and so, until recently, this author
had always presumed that after a hair fiber broke, the ends would fray (analogous to a rope)
Figure 9. S-N Plots for Caucasian and African hair as obtained from single fiber fatigue experiments.

433 SUSTAINABLE HAIR
and form a split end. However, recent experimental findings are refuting this idea. Figure
10 shows a high magnification, scanning electron microscopy (SEM) image of a broken
hair fiber (acquired from the aforementioned repeated grooming experiments) that exhibits
both fibrillation and splitting.
Fibrillation and splitting are commonly seen when examining broken fibers that result
from these experiments (although not necessarily together) however, Figure 11 suggests
that fibrillation occurs prior to breakage rather than in the presumed reverse scenario. This
image was obtained from surveying the topography of the fiber in the immediate vicinity
of the break. In doing so, it was similarly common to find longitudinal cracks in the fibers,
as shown in Figure 12. Both of these occurrences are presumed to result from extreme
bending stimuli that fibers can encounter during hair grooming. It appears logical that a
spit end is obtained if such a crack initiates or terminates at a fiber tip.
Fiber tips, such as that in Figure 10, cannot be technically “repaired.” While “split end
repair” is an attractive consumer proposition, it is not possible to even conceptualize a
means of restoration. As per the previous discourses, the alternative is to temporarily
hide the occurrence such that the consumer does not notice. To this end, it is sometimes
Figure 10. Split end and fibrillation in a broken hair fiber.
Figure 11. Fibrillation prior to breakage.