Study Set Content:
The principal active ingredient in most of the neutralizing formulation is acidic() at a concentration of ()%. S
hydrogen peroxide, 1 to 3
are occasionally used on account of their good stability and absence of bleaching power.
Sodium bromate and sodium chlorite
such as cationic surfactants or silicone emulsions, are often included to ensure easy combing, smooth texture, and control of fly-away of the waved hair.
H2 O2-compatible conditioning agents
Although () is the defining adjective of the imparted wave, there are many other considerations that are important in the assessment of wave quality
“permanent
Among them are tightness of curl, its springiness, feel of the hair, its luster, and combability. ¨ Ultimately, the most reliable way of judging the characteristic of a wave is on the () of the consumer, and thus it is not surprising that this subjective approach has always been used as the final evaluative tool of product prototypes.
head
¨ The importance of using the consumers the testing probe is of particular importance in assessing the wearing characteristics of the imparted wave. ¨ So far, no satisfactory laboratory procedures have been developed to accurately () this important aspect.
mimic
The objective laboratory measurements on both hair tresses and single fibers are the backbone of the development of new prototypes, screening processes, and further evaluation of competitive products. ¨ () is particularly useful in differentiating between different chemical systems (e.g., TGA vs. sulfite, alkaline vs. acid wave) providing rapid information as to the efficacy of the process.
Single-fiber technique
¨ Some measure of the durability can be gained by submitting these () to the action of hot water, detergents, and stress.
¨ Using calibrated fibers, the mechanical measurements can provide the first impression of process ().
microsprings, aggressiveness
Although the molecular mechanism underlying hair-straightening parallels that of waving or setting of hair, there are some distinct differences in the composition of formulations and, naturally, in the
mode of their application
There are essentially two different categories of straightening preparations;
o those that aim at temporary straightening
o those designed to accomplish permanent effects
¨ The most frequently used technique in this category is(). An ()material (pressing oil) is applied to hair, which is then combed under slight tension with a heated comb
hot combing, oily
The straightening effect is produced by the combined action of()() present in hair.
heat and the moisture
¨ The function of the pressing oil is threefold:
(1) to act as a () ()- transfer agent between the comb and the hair
(2) to serve as a () reducing the drag of the comb,
(3) to function as a () slowing () into the hair of moisture from the scalp and environment, and thus delaying reversal of the straightening effect.
protective heat, lubricant, barrier, diffusion
¨ Pressing oils are mostly based on() blended with some(). ¨ Frequent combing dulls and damages the hair, leading ultimately to ().
petrolatum and mineral oil, wax and perfume, hair breakage
The most effective class of permanent straighteners (relaxers) is that based on () as an active ingredient.
alkali
()()() in combination with () are used at concentrations of 1.5 to 3% in a heavy cream base.
Sodium or potassium hydroxide or sodium carbonate, guanidine
Even though the recommended treatment time is only() minutes, the straightening effects in general, surpass those obtained with either thioglycollates or bisulfites because of the different chemistry of the process and the greater aggressiveness of alkaline relaxers.
5 to 20
treatment irreversibly decreases the cystine content of hair to two thirds of its initial value.
15-minute
has also been used as the active ingredient in relaxers, although in somewhat different form from that encountered in conventional waving lotions.
Alkaline thioglycollate
are always thin, promoting a fast lotion penetration into the tightly wrapped hair on the curler
Alkaline thioglycollate
