Conditioning Agents for Hair and Skin

Evaluating Effects of Condttk>nlng Formulatlona on Hair 307
Untreated hair after
shampooing; combing
measurement
(1)
Chemical treatment
through windows;
rinsing with water and
shampooing.
(2)
Removal of the
treatment frame;
combing measurement.
(3)
Exposure of the whole
tress to conditioner
treatment followed by
rinsing; combing
measurement.
(4)
Rgure 3 A scheme of the experimental protocol for using spatially resolved combing
analysis of hair.
experiments allow for an accurate assessment of the effectiveness of a conditioning
treatment and its substantivity to hair. To obtain statistically significant
data, the measurements must be performed in replicate on several tresses.
A modification of the basic procedure, termed spatially resolved combing
analysis, can be particularly useful to detect and quantify conditioning effects
on hair damaged by chemical treatments and by heat or photo exposure. A
detailed description of the technique is provided in Ref. 26 with one of the
experimental protocols presented schematically in Figure 3. In this method,
special frames are employed which allow the application of a treatment to
selected areas of the fibers while shielding the remaining jwrtions of the tress,
thereby providing internal reference sections. The combing traces of hair
treated in such a way show positive or negative peaks depending on whether
the treatment results in an increase or a decrease in friction against the hair
surface. The damaging or conditioning effects can be further quantified by
calculating the differences in combing force or work values corresponding to
the treated areas. Figure 4 presents an example of the application of this
method to study the effect of bleaching followed by conditioning with a cationic
polymer. Bleaching results in a three- to fourfold increase in combing
forces as compared to untreated hair, while subsequent application of a polymer
solution decreases the combing forces. The shape of the combing curve