News Release
July 21, 2015

Determination of the Damage Control Mechanism Provided byInterim Washing During Perming~Establishment of New Technology that “Elasticizes” Hair in Order to Analyze its Structure~

The Milbon Co., Ltd. (President and CEO: Ryuji Sato) Central Research Institute has worked incollaboration with Doctor Kozo Arai from the KRA Wool Research Laboratory and Professor Kunihiro
Hamada from the Faculty of Textile Science and Technology at Shinshu University to discover that alengthy period of interim washing during the perming process leads to a large reduction in the damage
caused to hair. Furthermore, through the establishment of new technology that processes hair in order toturn it into an expandable state, similar to that of rubber, and then analyzes its internal structure, themechanism by which this interim washing controls damage has also been determined.
In the past, a great deal of the research into controlling damage to the hair during perming has been
focused on perming agents*1. However, these new research results indicate that not only the perming agents
but also changes to the perming process itself can help reduce the damage caused to hair. They can beconsidered results that will lead to the development of new hair damage control technologies.
These new findings are intended to be reflected in the development of perming agents and hairstraightening agents in the future.
These research results were published in the following scientific journal.
[Thesis]Publication: Sen’i Gakkaishi, 2015, Vol. 71 Issue 2, Pages 112-120
Thesis Title: Reproduction Mechanism of SS Cross-Links in Permed Hair by Washing after Reduction in
Thioglycolic Acid
Authors: Kazuyuki Suzuta (Milbon), Kunihiro Hamada (Shinshu University), Kozo Arai (KRA Wool
Research Laboratory)DOI Number: http://dx.doi.org/10.2115/fiber.71.112[Research Background]
Perming is an important technique, central to the beauty salon business and significantly expanding thepossible range of hairstyles. However, many points remain unknown concerning the causes of damage tohair during the process and the detailed mechanisms behind them, and further research was required.
The majority of perming processes use the following 5 steps.
(1) Winding: The hair is wound onto rods.
(2) 1st Agent Treatment: The 1st agent is applied to the hair and then left for a period of time.
(3) Interim Washing: The hair is washed with water and the 1st agent removed.
(4) 2nd Agent Treatment: The 2nd agent is applied to the hair and then left for a period of time.
-1-(5) Washing & Drying: The hair is washed with water and then dried with a dryer etc.
Almost all of the past research into the damage caused to hair by perming has been focused on theperming agents, and the effects on the hair caused by the other steps in this process have not beenthoroughly investigated.
Milbon therefore settled upon step 3 in the above perming process, Interim Washing, and proceededwith research into the effects that interim washing has on the hair.

-2-[Research Results]~ Control of Damage to Hair Using Interim Washing ~Hair was permed using a range of different interim washing times, and the degree of damage caused to
it by the perming process was then evaluated by measuring the tensile strength*2 of the hair. Interim
washing during a standard perm is normally performed for a few minutes, but it was discovered that
extending the period of interim washing greatly reduced the damage caused to the hair, (fig. 1).
~ Establishment of New Technology that “Elasticizes” Hair in Order to Analyze its Structure ~Hair is formed from a protein called keratin. It is comprised of a large number of disulfide bonds*3, which
recent research has determined can be classified into a variety of types depending upon their properties
and functions. When disulfide bonds connect two proteins together it is called “intermolecular disulfidelinkage,” and these are thought to be the bonds that affect the strength of hair and in turn are affected byany damage to it. However, existing methods have never allowed for this intermolecular disulfide linkage
to be analyzed separately from other types of bonds.
We therefore undertook the development of a process to analyze intermolecular disulfide linkage inisolation. When hair is treated with a special reagent it is transformed into a “rubber–like” state that allows
it to expand and contract a great deal more than normal (fig. 2). By applying rubber elasticity theory*4 - atheory developed through research in such fields as industrial rubber - to this “elasticized” hair a method
has been developed that allows just the condition of the intermolecular disulfide linkage within the hair tobe analyzed.
~ The Mechanism of Damage Control Through Interim Washing ~Using this new analytical method to investigate the changes in disulfide bonds during the interim
washing process revealed that the longer the interim washing is performed for, the greater the reduction in
the volume of lost intermolecular disulfide linkage (fig. 3). This correlates with the trend for interim
washing time to reduce the damage taken by hair (fig. 1). Furthermore, it was discovered that the volumeof intermolecular disulfide linkage is reduced by the 1st perming agent, but then increases again during
interim washing (fig. 4).
It was therefore discovered for the first time ever that the reformation of intermolecular disulfide linkage
via interim washing can be used to reduce the damage caused to hair during perming.
~Conclusion~
It has generally been thought that due to the damage to hair during perming being caused by theperming agents, improvements to those agents were required in order to limit the damage caused to thehair. This research has shown that damage may be controlled not only by the perming agents but also byadjusting the “interim washing” step of the perming process. These results will be used as new technology
for the prevention of damage to hair in the development of perming agents and hair straightening agents.
-3-2520

強度 / 107 N m-2

ダメージ
Less Damage
小A
54

15

3
2

1

10Strength5

More Damage
ダメージ
大0
1.0

1.2

1.4
1.6
伸長比Ratio
Extension

1.8

2.0

Fig.1 Changes in hair strength due to interim washing length during the perming process.
Interim washing times as 1: 1 min, 2: 20 mins, 3: 4 hours, 4: 24 hours, 5: 72 hours.
A is hair prior to being permed.
The longer interim washing is performed for, the stronger hair remains and the less damage it takes.

Expand伸ばす

Contract
縮めるFig. 2 The expansion and contraction of “elasticized” hair.

-4-ずり弾性率 / 106 N m-2

分子間ジスルフィド
結合量が多いShear

4Greater Volume of3

Intermolecular
Disulfide Linkage

212 hours

72時間

4 hours

24時間

1 hour

12時間

Perm

20 mins

4時間

1 min

1時間

Prior to20分

Prior to Perm

1分

ーマ施術前

0

パーマ
施術前

Modulus 1

24 hours 72 hours

Fig.3 Changes in shear modulus in “elasticized” hair by interim washing time during the perming process.
The longer interim washing is performed for, the greater the volume of maintained

ShearModulus

4分子間ジスルフィド
結合量が多いずり弾性率 / 106 N m-2

intermolecular disulfide links. This trend correlates with the reduction in damage seen in fig. 1.

Greater Volume of3

IntermolecularDisulfide Linkage

210

パーマ
施術前

Prior to Perm

第１剤施術＋
1st Agent
Treatment + 1
1分間水洗後Minute Washing

24時間
After 24
Hours
水洗後
Washing

第２剤
After
2nd Agent
Treatment

施術後Fig. 4 Changes in shear modulus in accordance with steps in the perming process.
The intermolecular disulfide linkage is reduced by the 1st agent, and then recovered through interim washing.

-5-<<Terminology>>*1 Perming Agents

The two solutions used during perming (1st agent and 2nd agent) are collectively known as “permingagents.” The reducing agent contained in the 1st agent breaks the disulfide bonds*3 found in hair, andthen the oxidizing agent found in the 2nd agent reconfigures the disulfide bonds. Use of the complete
perming process brings a curl to the hair.
*2 Tensile Strength
The size of the resistive force in the hair when it is placed under tension. Damaged hair has a lower
tensile strength.
*3 Disulfide Bonds
One of the bonds that can form between proteins using two sulfur (S) atoms. Also called SS-bonds.
*4 Rubber Elasticity Theory
A theory established in order to scientifically explain
高分子
Macromolecule

the elastic properties of rubber. Standard rubber iscomprised of a concentration of long, string like

分子間結合
Intermolecularbond

molecules (macromolecules) joined by many bonds

Macromolecule
高分子(intermolecular bonds) to create a net-like structure.
When rubber like this is analyzed using rubber

ゴムの網目構造

elasticity theory, the state of the intermolecularComposition of Rubber

The Net-Likebonds can be determined.

■Inquiries relating to the press release
Public Relations Unit, 2-3-35 Zengenji-cho, Miyakojima-ku, Osaka
Phone: +81-6-6928-2331, Fax: +81-6-6925-2301
Milbon Co., Ltd / Ryuji Sato, President & CEO; Head Office Miyakojima-ku, Osaka; Securities Code 4919, First Section of the Tokyo Stock Exchange-6-