|
THE
POTENTIAL TEXTILE UTILIZATION OF THE DOWN FIBRES FROM SOUTH AFRICAN
DAMARA SHEEP BREED
COUNCIL FOR
SCIENTIFIC AND INDUSTRIAL RESEARCH (CSIR)
Albie Braun - 17
September 2004
Introduction
The unique and
highly desirable characteristics of luxury animal fibres, such as
softness and comfort, have increasingly been sought after by discerning
customers world-wide. There has also been a trend towards lighter,
casual and easy care garments.
Although
not classified as a luxury fibre, wool is the most widely produced and
popular animal fibre, possessing highly desirable properties. Because of
their superb softness and comfort, fine wool (finer than 18 micron) and
cashmere are two of the world’s most sought after animal fibres today.
In
the light of the above and the fact that certain indigenous goats and
sheep breeds have the potential to produce a fine "down"
cashmere type of fibre, the CSIR, together with other stakeholders, has
embarked on various projects aimed at investigating the economic
feasibility of, and requirements for, utilising fine down components of
indigenous goats and sheep breeds for producing marketable products, one
such sheep breed being the Damara.
This
report addresses results obtained on fibre samples obtained from the
Damara double-coated sheep breed found in South Africa.
Sheep
breeds
From a textile
view point wool from sheep can be sub-divided into 3 main groups, namely
(1) wool shorn from living sheep (shorn/virgin wool) (2) wool removed
from skins (skin wool, slipe wool or dead wool) and (3) re-used
(non-virgin) wool. Sheep breeds, which are primarily wool producers, can
be sub-divided according to the type and fineness of fibre they produce
and the end products made from these fibres. For example breeds, such as
the merino and merino related breeds, which produce primarily apparel
type wool (i.e. fine or medium wool) and those breeds which produce a
coarse wool used for carpets i.e. Lincoln.
The
above-mentioned wools grow throughout the entire year and the fleece is
of a single component. There are other sheep breeds, such as the Dorper,
which are primarily mutton producers but which also produce a medium to
coarse type of wool and hair covering as a by-product to meat
production. There are also the fat-tailed mutton producing sheep breeds,
which possess the ability to produce a fleece consisting of two distinct
coats of fine and coarse fibres, namely a fine down or undercoat and a
coarse hair or guard coat. The coarse outer coat or guard hair component
protects the body of the animal. The Damara, Ronderib Afrikaner, Pedi,
Van Rooy, and the Blackhead Persian are good examples. Most of these
breeds possess the inherent ability to respond to seasonal changes in
day length and climatic conditions resulting in periods of an active
fibre growth and then of fibre shedding (moulting). In South Africa, the
down fibre grows actively from December to June, thereby protecting the
animal from the cold in winter while shedding of the down fibres takes
place during early spring (July to September) so that the animal does
not suffer from excessive heat during the hot summer months. Generally,
the fat-tailed sheep breeds are found in arid or semi-arid regions of
the country where food is sparse.
The
Damara sheep breed possesses the ability to produce a fleece consisting
of two distinct coats (fine and coarse fibres).
Purpose
of Investigation
In view of the
great demand for the cashmere type of fine down world wide and the
potential for employment creation and value addition, the CSIR extended
its indigenous goat initiative to also include the double coated fleece
of fat-tailed mutton sheep breeds, such as the Damara sheep breed found
in South Africa.
Harvesting of
fine down fibre
During the
shedding / moulting period the animal releases the down fibre freely
from its body but it can also be harvested by combing the animal and the
fibre collected. The shedded/combed fibre consists of both fine down
(undercoat) and coarse hair (guard coat) which requires a mechanical
process, called dehairing, in order to separate the two components.
Results
and Discussion
An initial
investigation of various fat-tailed sheep breeds showed that the Damara
was one of the breeds with the finest down. (Table 1)
Table 1 gives a
summary of the fiber properties (quality and yield) of the Damara and
various other sheep breeds and compares the diameter profiles with those
of dehaired Chinese cashmere and with dehaired down of the South African
Boer Goat.
For easy and
efficient dehairing there needs to be a clear distinction between the
two fibre populations (fine and coarse). It is generally desirable that
the ratio of the diameter of the outer coarse coat (guard hair) to that
of the fine down fibre component at least be 4:1 and that the outer coat
have a mean fibre diameter greater than 60 micron. For this reason, the
presence of intermediate fibres (30 to 60 micron) in the fleece is
undesirable because it is difficult to remove such fibres during the
dehairing process.
According to
Table1, the fine fibre component of the Damara compares favourably with
cashmere down in terms of fineness, down fibre and guard hair diameter
ratio (1:4) with a good diameter profile i.e. without indications of
intermediate fibres. Nevertheless, the down fibre yield is comparatively
low at 39%.
Processing
of Damara hair
It was also
considered necessary to determine the acceptability of the fine down
fibre as a textile fibre, i.e. in terms of textile processing
performance and conversion into acceptable garments. To this end Mr. Mr
Dennis Steenkamp of the Damara breeders Association were approached to
supply fibre for processing purposes. The ± 350kg of combed fibre
supplied was scoured (washed) in South Africa and dehaired (mechanical
separation of the coarse guard component from the fine down fibre
component) in the UK after which the down fibre was processed into yarn
and knitted garments by the CSIR. Garments were produced from pure
Damara wool as well as from blends of Damara wool with either viscose
fibre or Mopanie silk. Because the dehaired fibre is very short (±
16mm), processing into yarn was carried out on short staple machinery.
Processing
stages
Process
Product
1. Scouring
(washing)
Scoured fibre
2. Dehairing
(mechanical separation)
Coarse hair component
Fine down component
3. Carding of
down component
Card sliver
4. Drawing
Sliver
5 Roving
Roving
6. Spinning
Spun yarn
7. Twisting
Plied yarn
8. Dyeing
Dyed yarn
9. Knitting
Garment
Economic
Potential
Fibre Yield per animal*/ Fibre weight (g.)
Raw fibre
50
Scoured fibre
(74% of greasy fibre)
37
Down fibre (39%
of scouring yield)
14
Final Down
Yield (after processing and making-up)
13
Down fibre per
animal in final product
13
The
above indicates that assuming that an animal producers 50 grams of raw
fibre which yields 13grams of fine down fibres and a knitted garment of
500grams means that the down from 39 sheep is required to produce the
garment.
Conclusion
The
availability of the Damara sheep breed offers an opportunity for the
diversification of existing agricultural resources without a large
capital outlay. The utilization of the fibres as an additional source of
income (value addition) could make this mutton breed more profitable.
The fibre characteristics, notably fineness and yield, of the Damara
sheep breed were therefore investigated with a view to assessing the
potential of the undercoat as a textile fibre and for value addition. It
was found that the Damara sheep breed showed potential in terms of the
utilisation of their fine undercoat fibres in the high value added
textiles with an African design. Nevertheless the yield per sheep of
fine down fibre would need to be substantially increase for this to
become a reality
The recent
acquisition of a dehairing facility in South Africa provides the
opportunity for South Africa Damara sheep farmers to exploit the
potential and ability of the Damara sheep breed to produce fine, high
quality unique garments.
|
