Development of garment leather from Yellowfin tuna (Thunnus albacares) skin
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Date
2015
Journal Title
Journal ISSN
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
Leather is defined as hide or skin with its original fibrous structure more or less intact, tanned to
prevent putrefaction (Covington, 2009). Due to tanning, skins that have been processed to prevent
putrefaction retain its characteristics such as flexibility and toughness. Hides and skins from cattle,
buffalo, sheep, pig, goat, horse, crocodile, snake and fish are used for leather production. When
considering the fish leather, fish skins are used for production of leather after tanning and re-tanning
processes. Texture of fish leather depends on pocket size of the scales. Presently, carp, pacific salmon,
bass, sturgeon, shark, tuna, catfish, salmon, tilapia and several other fish species are taken for leather
production. Garment leather is tanned with chrome and treated with softeners. The quality of the
garment leather should be thin enough to use on garments and it should feels softer and smoother
than any other types of leather. These types of leathers are made from the top-grain of a hide. Good
stitch tensile strength and light weight are some other characters of garment leathers. Cow hide and
skins from deer, pig and lamb are commonly used for garment leather manufacturing. But there is a
potential to develop garment leather from fish skin similar to other garment leathers. The present
study was carried out to add value to waste generated during the Yellowfin tuna (Thunnus albacares)
fish processing and promote a fish leather production in Sri Lanka through developing garment type
leather using discarded skins. At present, hides and skins from cattle, buffalo, sheep and goat are used
for leather production. In addition, fish species including carp, pacific salmon, shark, tuna, catfish
and tilapia are taken for leather production in the world. The objectives of this study were to find out
the best fat liquor percentage to obtain maximum softness of chrome-tanned Yellowfin tuna fish
leather and to find out the best tanning method for garment leather production from Yellowfin tuna
skin.
Methodology
The current study was carried out at the tannery of Ceylon Leather Product PLC (CLP), Mattakkuliya.
Tuna skins were collected from the processing factory of Jay Sea Food (Pvt) Ltd in Ja-Ela. Two
experiments were carried out to find out best fat liquor concentration and best tanning method. In
experiment 1, yellowfin tuna skins were treated with 33% basic chromium sulphate and five different
concentrations (12%, 14%, 16%, 18% and 20%) of fat liquors (on weight of pelt). In experiment 2,
yellowfin tuna skins were treated with four different tanning methods (Full chrome tanning, full
vegetable tanning and two types of semi chrome tanning methods - vegetable tanned skins directly
tanned with chrome and vegetable tanned skins tanned with chrome after stripping with NaHCO3).
Before initiating the experiments pre-trial was conducted to find out the optimum conditions for
liming. Six pieces of raw skins were immersed in solutions of 0.25%, 0.5% and 1% Na2S, 6%
Ca(OH)2 and 200% water (on weight of skins). One day after, skins were taken out and scales and
flesh were removed. Then, skins were kept for another 5 days in a new 6% Ca(OH)2 solution. Weight
and the physical conditions (scale pockets, colour and plumpness) of the skin were observed daily.
After identifying the optimum conditions for liming 40 skins were subjected to 8 production process
steps (liming, de-liming, pickling, tanning, basifying, fat-liquoring, fixing, drying and dying).
Experiment 1 was done in fat-liquoring step and experiment 2 was done in tanning step. Then, the
dried leathers were dyed and waxed. Finally softness, feel, tensile strength, tear strength and stitch
tear strength were measured in developed leathers. Physical evaluation was done to check softness
and feel by ten expertise. Tensile strength, tear strength and stitch tear strength were done using
universal testing machine. This experiment was designed according to Complete Randomized Design
(CRD). The collected data were analyzed using Friedman test and one-way ANOVA in MINITAB
16 and SPSS 22 statistical analyzing software to find out the significant difference between
treatments. Mean separation was done using pairwise comparison.
Description
Keywords
Animal Sciences, Aquaculture and Fisheries, Aquatic Resources, Aquatic Products, Aquaculture