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Leather For Handcrafting

Study By

Santosh Kumar Jha PhD (Crafts), PGD(Crafts & Design), MBA(Marketing)

FOR HANDCRAFT

DESIGN &

DEVELOPMENT

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What is leather?

The British Standard Definition of leather is:

'Hide or skin with its original fibrous structure more or less

intact, tanned to be imputrescible. The hair or wool may, or

may not, have been removed. It is also made from a hide

or skin that has been split into layers or segmented either before or after tanning.'BS: 2780.

The amount of surface coating applied to the

leather influences whether or not the item can be described

as genuine leather.

'..If the leather has a surface coating, the mean thickness

of this surface layer, however applied, has to be 0.15mm or

less, and does not exceed 30% of the overall thickness'. BS: 2780.

What is not leather?

There are many types of

leather items sold and

described as leather,

when in actual fact they

are imitations. Some of

the more common ones

are described below.

Bonded Leather Fibre

'Hide or skin with its

original fibrous structure

more or less intact... If

the tanned hide is

disintegrated

mechanically and/or

chemically into fibrous

particles, mall pieces or

powders and then, with or

without a binding agent is

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made into sheets, such sheets are not leather' BS: 2780

It is possible to see the incorporation of several material

types within this bonded leather structure as different

colour types.

Advantages:

• Cheap • Uniform cutting area

Disadvantages:

• Not leather

• Poor flexibility

• Not durable

• Little strength • Looks cheap

Coated Leather

'A product where the finish thickness does not exceed 30%

but is in excess of 0.15mm'

The darker region toward

the grain side of the

leather contains the

actual coating, which can

be constructed with

various chemical

materials, such as a

polyurethane mix. As the

finish thickness exceeds

0.15mm, it cannot be termed genuine leather.

Advantages:

• Cheap • Consistent surface

Disadvantages:

• Lacks natural look

• Not porous

• Physical performance, flex etc (low)

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Laminated Leather

The main features of laminated leathers are that they are a

composite of two or more layers, where the laminate has

been affixed to the flesh side. Also a difference between

this leather type and a coated leather is that the laminate

accounts for greater than 30% of the leathers overall

thickness.

Advantages:

• Consistent surface

• Some flexibility and strength • Colour and light fastness good

Disadvantages:

• Lacks natural look

• Not porous • Physical performance not as good (tends to crack)

How much of a product

should be leather?

You may have bought a

pair of leather shoes or a

leather wallet, and having

looked at it closely

wondered just how much

of it is leather and how it

can be sold as a 'genuine leather' article.

Manufacturers of leather

articles are allowed to

construct a product that is

traded as 'genuine

leather' with non-leather

materials provided the

incorporation on non-

leather materials does not exceed specific levels.

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The EC Directive 94/11 on Footwear Labelling states that a

genuine leather shoe must contain the following proportions of leather:

• Upper - 80% of surface area

• Lining/Sock - 80% of surface area • Sole - 80% of volume

'If no one material accounts for at least 80%, information

should be given on the two main materials used in the composition of the footwear.'

Guidelines

The following are general guidelines regarding the composition of leather articles:

Watch Straps/Belts

Where both the outer layer and lining are leather, then it

can be described as leather, genuine leather, or real leather

provided no other materials comprise more than 50% of

the surface area.

However, if a strap or belt

meets the previous

definition of leather but at

the same time clearly

comprises less than 50%

leather in total volume,

then it should not be

described as leather

without further

qualification as this may be misleading.

Upholstery

There are essentially two

zones: "contact areas"

i.e. seats, arm rests,

vertical seat backs and

rolls, and "non-contact

areas" e.g. outside arms

and back. Furniture

should only be described

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as "leather" if both the "contact" and "non-contact" areas

are leather. Where only the "contact areas" are leather then

the furniture should not be described as "leather" unless

the description "leather chair with non leather areas" is used.

Sometimes the term "leather faced" is used under these circumstances.

Luggage, Bags, Leathergoods

At least 80% of the surface area of the main body should

be leather (excluding internal dividers, pockets, pen holders etc.)

More Information

Leather Descriptions and Definitions (1.2MB PDF) - Includes

definitions of different types of leather.

British Standards

Faking it

There are alternatives

that don't attempt to

imitate leather and there

are substitutes which are

designed to imitate

leather. These substitutes

are legal if sold as such,

but become fakes when

they are passed off as leather.

Another product

sometimes falsely

described as leather is

made by compacting

leather fibres with a

binding agent to hold

them together. Because

the fibres are stuck

together rather than

interwoven the product

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lacks the flexibility and durability of real leather. Legally this material must be described as 'bonded leather fibre'.

If you are concerned about a leather item that you feel is

not ‘leather', or for other assistance with consumer

protection issues in the UK contact your local Trading

Standards office which you can find via the Trading Standards Website.

Areas

You'd be surprised the first time you see a full hide. Not

only are they much larger than you think, they vary much more than you'd expect too.

Leather from different parts of the animal varies in its

characteristics, and this has to be taken into account when

using leather in products. The hide thickness varies all over

the animal, and to get it to the right thickness it is usually

split on a special cutting machine or buffed to an even

thickness. The main parts of the hide are shown in the diagram below

Shoulder - the shoulder

is thick and strong but

tends to crease easily as

this part of the hide is

affected by movements of the head

Butt - the fibres in this

part of the hide are

tightly packed and hence

the strongest part of the hide

Belly - this part of the

hide is quite thin and has

a much looser fibre

structure than the back,

and often stretches under stress.

Axillae - these are like

the human armpits - they

move a lot - so the fibre

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structure is quite loose, making it even more prone to loosening than the belly areas.

From Hide to Hair

Different parts of a hide have different properties in terms

of strength, flexibility and durability. This makes some parts

of a hide more suitable for use in sofa manufacturing than others.

Science

For a material that is so versatile, stylish and practical you

could be fooled into thinking it is an extremely complicated

material...far from it! There are basically just three main

materials from which hides and skins are made :-

• Water 60-65%

• Protein 25-30% • Fats 5-10%

The protein is mainly

collagen (found in many

cosmetics) and it is this

collagen that is

transformed into leather by the tanning process.

In good shape

Raw hides and skins have

four main parts - an

epidermis, grain, corium

and flesh - as shown in the diagram below :-

Two of these layers - the

epidermis (which is a thin

protective layer of cells

during the life of an

animal) and fleshy

remains - are removed

during tanning by a

process called liming. This

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leaves just the grain and the corium, the interesting parts!

The grain layer is made of collagen and elastin protein

fibres (found in many moisturisers and facial creams), and

its structure varies quite a bit depending on the age, breed

and lifestyle of the animal. The grain carries many

distinctive marks such as insect bites, growth marks and wound scars giving the leather a unique appearance.

The corium is packed with collagen protein fibres, arranged

in larger bundles and interwoven to give the structure great strength, excellent elasticity and durability.

The thickness of the corium increases with age which is why

calfskins are thinner, smoother and softer than the hides of

mature animals. Hides from cows are smoother, thinner

and softer than the hides of mature male bull hides which are thick, tough, course grained and very strong.

Thick hides are often too thick for their end use and so they

sometimes have to be split layerwise through the corium to

give what we call a ‘grain split' - used for grain leather -

and a ‘flesh split', used mainly for suede leather. Another

little trick is to apply an

artificial grain layer to the

flesh split to make it look

like grain leather!

However the strength of

these so called ‘finished

split' leathers is reduced

since the corium lacks the

strength of the corium found in the grain layer.

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Thanks To primary information source:

Web Source: http://www.all-about-leather.co.uk

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