438 JOURNAL OF COSMETIC SCIENCE
author to previously propose a definition that frizz is “an inability to attain a high degree
of hair alignment or some partial loss of this state after an initial degree of success.”37
This definition encompasses the innate nature of highly curly textured hair, as well as the
static flyaway that that can be encountered under low humidity winter conditions and/or
during heat styling. It similarly covers the loss of heat-straightened styles, especially in
high humidity conditions.
The properties of textured hair will be covered later in the article, but here the current
focus is directed to straighter hair issues. As per the previous discourse on water and hair,
temporary styles can be attained via heat styling tools that drive water from the hair
and set up additional electrostatic bonding within fibers. However, upon completion of
this process, the hair will immediately begin to readsorb moisture from the surrounding
atmosphere to a level that is dictated by the hair-water adsorption isotherm (see Figure 14).
The new electrostatic bonds are solvated, and the outcome is a progressive reversion of the
induced style to its initial state. The loss of a previously crafted sleek, straight styles to a
curlier (misaligned) state is frequently termed “frizz.”
Under low moisture conditions, friction between hair and a brush/comb/styling appliance
can induce static charge buildup on the surface of hair fibers which causes them to repel
their neighbors. The result is a flyaway appearance, which we technically describe as low
humidity frizz. This occurrence can be commonplace when the relative humidity is low
or when employing heat styling to remove water from hair. Traditional hair conditioners
can sizably mediate this negative, presumably by helping lower frictional forces, increase
surface conductivity, and adjust hair’s position in the triboelectric series.37
Perhaps the most perplexing consumer expressions are the related properties of “volume”
and “body.”38 To scientists, volume has a very straightforward definition involving the 3D
space that an object takes up. However, while straight, limp hair may be thought of lacking
volume, extremely curly hair might have too much volume to the point that it’s described
as “frizzy.” So, to some consumers, “improving volume” might involve increasing its spacial
footprint (so-called volume up), while to others, the reverse might be true (volume down).
In short, once again, technical language does not straightforwardly equate to consumer
language, and measurement of this property is not as simple as an image analysis approach
to yield a pixel count.
Certain fundamental hair parameters have repeatedly been identified as being associated
with hair volume and body.39 These attributes are thought of as difficult to attain when
fibers are relatively thin, have lesser stiffness, and fiber density on the scalp is lower. Some
fiber curvature is thought necessary, as is a degree of interfiber friction. Yet, from a cosmetic
perspective, we have little control over most of these. A moment of clarity for this author was
attained when watching a consumer study where women were asked to create a high-volume
style. Later the same panelists were asked to re-wash their hair and repeat the process but,
this time, without using their style creation products (i.e., mousse and/or gel). Without these
products, the panelists struggled to control and manipulate the hair during blow drying and
styling, and the end result was never close to that of the earlier attempt. This observation
illustrated that these properties are not necessarily innate to the hair, but instead relate to
the ease and ability with which these desired states can be created. Unquestionably, this
occurrence can have a dependence on the native properties of the hair where it may be easier
in some cases than others. At the same time, skilled hairdressers can create volume and
body in even the limpest hair due to more advanced skills. Style creation products afford

439 SUSTAINABLE HAIR
an improved ability for gripping and manipulating the hair. Conventional hair conditioner
products have traditionally been thought of as having an adverse influence on volume
and body where it is felt that deposits potentially weigh down the hair. Here we come to
recognize a second issue where the resulting surface lubrication, while highly beneficial
during detangling, will hinder the ability to grip and manipulate the hair during styling.
To summarize, while visual properties of the hair can be measured and studied their
relationship back to consumer attributes are not straightforward.
HAIR REPAIR AND PROTECTION
By the time that hair emerges onto the scalp, it is biologically inert. It is commonly heard
that “hair consists of dead cells,” which is perhaps an overly dramatic descriptor, but,
unquestionably, there is no more biological activity taking place. The well-being of the
fibers’ structure is then in the hands of the wearer where abstention or minimizing the
highlighted insults will help prolong integrity. The human body has a remarkable ability
to heal itself, but the same is not true for passive hair. Once the cuticle structure has
begun to chip, crack, and uplift, and once the proteins structures of the cortex have begun
to degrade, there is no way back. The one saving grace is that hair continuously grows at
about 0.5 in per month so, the old, damaged hair can be cut off and gradually replaced by
regrowth. Indeed, the hair tips exhibit the highest levels of damage as these are oldest and
have accordingly accumulated the most wear and tear.
“Repair” is a common proposition in the marketing of hair-care products, which
would seem to be opposed to the above discourse. Instead, as already highlighted such
propositions generally relate to the alleviation of symptoms that signify damage. The
lubrication provided by conditioner products can mask all manner of ills. It can smooth
degrading cuticle to mask sensorial negatives and minimize manageability issues. Lesser
grooming forces equate to lower fatiguing forces and an exponentially lesser tendency for
hair breakage and spit ends.
True technical repair of the surface cuticle topography would necessitate feats of
nanoengineering. Chips and cracks would need to be repaired, uplifted scales would need
to be flattened, and lost “tiles” would need to be replaced. The state of the hair surface
is commonly visualized using SEM yet a consequence of this ultra-high magnification
involves only visualizing a minuscule portion of the fiber. Thorough characterization should
involve looking at multiple sites across multiple hair fibers to provide a representative overall
assessment. The highly variable nature of hair means that the occasional highly damaged
spot might be found in hair that generally looks healthy (or vice versa). Unfortunately, all
too often, “evidence” for the above unreal scenarios is presented in terms of SEM images
that have been cherry-picked to tell the desired stories, rather than being representative
renditions.
Similarly, the highly complex, now inert, internal protein structure of hair (see Figure
5) cannot be restored to its initial integrity after “damage” sets in. This structure was
miraculously crafted deep within the hair follicle during growth by processes that we are
just beginning to understand. In recent years, the expression “bond builder” has become
increasingly commonplace in our industry, which, in literal technical terms, implies an
ability to further structure hair proteins to positive ends. Of course, the proposition is
rather nebulous with “which bonds?” rarely being addressed. The creation of any covalent