Session 3
Basic science
GH10
Trainer requirements to teach this session
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Handout
GH10.3.1 (2 pages)
Slide
GH10.3.1a
Slide
GH10.3.1b
Slide
GH10.3.2
Handout
GH10.3.3
Handout
GH10.3.4
Handout GH10.3.6
Learner Check for Session 3
Trainer notes
This session will cover:
3.1 T
he effects of humidity on hair
3.2 The physical effects of blow drying, finger
drying and heated styling processes on the
hair structure
3.3 How the incorrect application of heat can affect the hair and scalp
3.4. Why hair should be allowed to cool prior to
finishing
3.5 Why hair should be kept damp during the blow drying and finger drying processes
3.6 How heat protectors act to protect the hair
© Copyright Habia 2010 - All rights reserved.
Page 41 - Unit GH10 - Session 3.
Session 3
GH10
Basic science
3.1. The effects of humidity on hair
Ref: Handout GH10.3.1
Explain to learners that the structure of hair is quite
complex.
Explain to them that the ‘building blocks’ are amino
acids, which are formed into polypeptide chains that
take the shape of an alpha-helix – like a spring.
Tell them that a square is called a square because of
its shape, a circle is a circle because of its shape, etc.,
therefore an alpha-helix is so called because it is in the
shape of a spring or spiral.
Explain to learners that hair in its normal state
is not stretched and that this state is called
alpha keratin.
Tell them that it becomes beta keratin when it is
stretched. For example - when blowdried, finger dried
or heated equipment is used.
Remind them that wet hair or heated hair stretches
further than cool, dry hair. Explain that this is because
the heat or the moisture has broken some hydrogen
and salt bonds so the ‘springs’ of the polypeptide
chains can be lengthened.
Ref: Slide GH10.3.1a and GH10.3.1b
Show this slide and take learners over the structure of
a hair from amino acids to polypeptide chains.
Speak about polypeptide chains twisting with
one another and emphasise the way the bonds are
positioned – the disulphide bonds and most of the salt
bonds being positioned horizontally to hold the
structure together.
Page 42 - Unit GH10 - Session 3.
© Copyright Habia 2010 - All rights reserved.
Session 3
GH10
The hydrogen bonds tend to be vertically placed within
the loops of the helix to prevent them straightening out.
Now talk about the formation of protofibrils, microfibrils
and macrofibrils. Use the analogy of cotton fibres
twisting together to make thread, threads twisting
together to make rope and ropes making a cable. Tell
learners that there are many thousands of macrofibrils
in the cortex of each hair.
Hair is hygroscopic
Tell learners that hair is hygroscopic – it will absorb
moisture from wherever it can get it, including from the
air. Explain that it does this in the same way that
blotting paper soaks up moisture – by capillary action.
This means that the moisture is passed through the
structure of the material from cell to cell.
Now tell learners that humidity refers to the amount of
water vapour in the air and hair will absorb moisture at
different speeds. Explain that hair that has low porosity
will absorb moisture slowly. The cuticle will be firmly
placed around the hair shaft and so the entry of any
liquid is slowed down. If the hair is porous it will
absorb moisture quickly because the cuticle will be
open (possibly due to damage).
Explain what happens when moisture is absorbed into
the hair:
•the cuticle opens slightly and the hair swells slightly
•the hair can stretch further because the hydrogen
and salt bonds break
•if the hair is not dried under tension into a stretched
position, the hydrogen and salt bonds will revert to
their normal, unstretched pattern
Ask learners which types of hair are
most likely to be porous.
© Copyright Habia 2010 - All rights reserved.
Page 43 - Unit GH10 - Session 3.
Session 3
GH10
Answers should include:
•chemically treated hair
•hair that has been damaged by chlorine
in swimming pools
•hair that has been physically damaged by
too much heat, rough handling
•hair that has been damaged by the
environment – sun, wind.
3.2 T
he physical effects of blow drying and
finger drying and heated styling processes
on the hair structure
Ref: Handout GH10.3.1 (recap)
Confirm the learners' understanding of hair structure:
•polypeptide chains link together to form fibrils that
make up the hair
•disulphide, salt and hydrogen bonds hold the
structure together.
Ref. Slide GH10.3.2
Show learners this slide and state that, when hair is
blowdried or finger dried it is stretched by fingers,
rollers, comb or brush and, if it is dried into the
stretched position, the hydrogen and salt bonds that
have been broken reform into new positions.
Tell them that they will stay in this new position until
the hair again becomes damp or very hot.
Remind learners that hair is hygroscopic – it absorbs
moisture from the air - steamy bathroom, the rain,
sweat from the scalp, etc…
Page 44 - Unit GH10 - Session 3.
© Copyright Habia 2010 - All rights reserved.
Session 3
GH10
Explain that this is enough to allow the hydrogen and
salt bonds to break again and, when the hair dries,
because it is not under tension (being stretched) the
bonds will go back to their natural, unstretched state.
Summary:
•when hair is in its natural, unstretched state,
it is alpha keratin
•when hair is wet and stretched slightly while blow
drying or finger drying it becomes beta keratin
•if the hair is dried into this stretched shape it
remains beta keratin
•when it becomes wet again when it reverts to its
normal, unstretched shape and goes back to being
alpha keratin
•when the hair is dried into a stretched shape it
keeps this shape because the hydrogen and the
salt bonds reform into a different pattern
3.3 H
ow the incorrect application of heat can
affect the hair and scalp
Ref Handout GH10.3.3
Tell learners to be aware of the dangers when using
heated tools/equipment – these tools can:
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damage the cuticle
cause hair breakage
burn the scalp
discolour the hair
Emphasise that they must not apply heat for too long
in the one place or too close to the scalp. Explain that
white or bleached hair becomes yellow, chemically
treated hair may fade and African Caribbean hair
becomes reddish if too much heat is applied to the
hair.
© Copyright Habia 2010 - All rights reserved.
Page 45 - Unit GH10 - Session 3.
Session 3
GH10
3.4 W
hy hair should be allowed to cool prior to finishing
3.5 Why hair should be kept damp during the
blow drying and finger drying processes
Ref: Handout GH10.3.4
Explain to learners that some of the salt and hydrogen
bonds will be broken by wetting and heating the hair
and state that, if they want the blowdry or finger dry to
last, they must dry the hair under tension so that the
bonds can reform in a new pattern.
Emphasise that, because heat as well as water causes
the bonds to break, the hair should be held under
tension until it cools. Tell them that, if they do this,
they will allow the bonds to set into their new shape.
Explain that, if they take the tension off while the hair is
still warm, some of the bonds will reform in their
natural, unstretched, alpha keratin shape.
Explain that this can be done by switching the heat
setting of the hair dryer to ‘cool’ and directing the cool
air over the hair.
Explain that, if they use heated styling equipment such
as tongs, straighteners or heated rollers they should
avoid disturbing the hair while it cools, let it cool
naturally – this is the next best thing to cooling it into
shape.
State that there are two main reasons why hair should
be allowed to cool before finishing:
• to achieve a longer-lasting effect
•to allow the hydrogen bonds to harden into their
new position
Explain to learners that they must change the natural
shape of the client’s hair if they want to achieve a
different look.
Page 46 - Unit GH10 - Session 3.
© Copyright Habia 2010 - All rights reserved.
Session 3
GH10
Tell them that they must change the hair from alpha to
beta keratin and that they can do this by wetting,
heating and stretching the hair slightly while styling it
into its new shape.
Remind learners that, if they allow the hair to dry
without being under tension, the hydrogen and salt
bonds will simply take their normal, unstretched, alpha
keratin position as the hair dries.
Explain that, if they allow this to happen, the bonds will
not take a new shape, even if they heat the hair – it
would have to be heated to quite a high degree - for
example using tongs or straighteners before the bonds
would change their position into a new, beta keratin
pattern.
Summary
When hair is wet:
• it stretches more than when it is dry
• a smoother effect can be achieved
•the hydrogen and salt bonds can be reformed into
a new shape to produce a style
Ask learners if the hair is in alpha or
beta keratin if it is wet but not stretched
Answer must be:
It is in alpha keratin – only stretched hair is
in beta keratin, irrespective of whether it is
wet or dry.
3.6 How heat protectors act to protect the hair
Handout GH10.3.6
Explain to the learners that heat protectors are styling
products that when applied to the hair put a heat
resistant coating on the hair.
© Copyright Habia 2010 - All rights reserved.
Page 47 - Unit GH10 - Session 3.
Session 3
GH10
Explain that heated styling equipment such as
straighteners and tongs can get very hot and heat
protectors are designed to help prevent damage from
these.
Heat protectors work in two ways:
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they smooth the outer layer of the hair - this allows
the heated equipment to easily slide over the hair
they withstand the high temperatures from heated
styling equipment and allow time for the hair bonds
to be rearranged in a new shape.
Now complete the Learner Check for
Session 3 to check learners’
understanding.
Page 48 - Unit GH10 - Session 3.
© Copyright Habia 2010 - All rights reserved.
Session 3
Basic science
GH10
Learner Check
Session 3
1. Hair is hygroscopic – what does
this mean?
1. It will absorb moisture into itself.
2. State the types of hair that are
likely to be porous.
2. a) Chemically treated hair
b) Physically damaged hair
c)Hair damaged by the
environment
3. Describe the changes that occur
in the hair structure during styling
3. Hair in natural unstretched state
is alpha keratin, hair that is wet
with hydrogen bonds that have
been broken is beta keratin,
hair that is dried, heated and
stretched into a new shape
remains in beta keratin.
4. What happens to the hair
structure when hair becomes
wet again after a blow dry?
4. It returns to alpha keratin.
5. State how the incorrect
application of heat can affect
the hair and scalp.
5.
6. Why should hair be allowed to
cool prior to finishing?
6. To ensure the reformed hydrogen
bonds are fixed in place.
7. How do heat protectors work?
Se
7. Smooth the outer layer of the hair
and withstand the high
temperatures from heated
equipment
© Copyright Habia 2010 - All rights reserved.
a)
b)
c)
d)
Damage the cuticle
Cause hair breakage
Burn the scalp
Discolour the hair
Page 49 - Unit GH10 - Session 3.
Session 3
GH10
Page 50 - Unit GH10 - Session 3.
© Copyright Habia 2010 - All rights reserved.
Session 3
Basic Science
GH10
Trainer Summary
3.1 The effects of humidity on hair
Remind learners of:
•
•
•
•
•
the hair structure
the disulphide, hydrogen and salt bonds
protofibrils, microfibrils and macrofibrils
hygroscopicity
humidity
3.2 T
he physical effects of blow drying, finger
drying and heated styling processes on the
hair structure
3.3 How the incorrect application of heat can
affect the hair and scalp
Remind learners of:
• alpha keratin and beta keratin
•the dangers involved in the use of heated styling
tools and equipment
3.4. W
hy hair should be allowed to cool prior to
finishing
3.5 Why hair should be kept damp during the blow drying and finger drying processes
•allowing hydrogen bonds time to ‘harden’ into
their new shape
•dry hair under tension - hair stretches more
when wet
3.6 How heat protectors act to protect the hair
•smooth the outer layer of the hair
•they withstand the high temperatures from
heated styling equipment
© Copyright Habia 2010 - All rights reserved.
Page 51 - Unit GH10 - Session 3.
Session 3
GH10
Basic science
Key/Core Skill Opportunities
Functional/Essential Skills
Opportunities
There will be an opportunity to promote discussion
when covering:
Handout
Page 52 - Unit GH10 - Session 3.
GH10.3.3 Ways of preventing too
much heat from being
applied to the hair or scalp.
© Copyright Habia 2010 - All rights reserved.