Various physical, chemical and fastness properties are required from leather products depending on their field of use. The range of physical properties determines the quality of product. The types include mineral tanning include (chromium, aluminum, iron, zinc), vegetable tanning (mimosa, acacia, quebracho), aldehyde tanning (glutaldehyde, formaldehyde) and oil tanning. There are different types of tannage available depending on the quality of the leather need by the consumer. Leather processing involves three sub stages pretanning, tanning and post tanning and finishing. Kenya having a good strong base for fish industry there is need to pursue the production of fish leather. The leather industry gets its raw materials form hides and skins of cattle, camel, sheep and goat and also from exotic sources such as ostrich, rabbit, crocodiles and fish. Leather can be used for various purposes such as making of handbags, belts, clothing, small accessories and shoes, furniture, interior decoration. Leather has good hydrothermal stability, good mechanical properties, and its resistance to chemical and biological degradation helps it to be used in various applications. Tanning is the process by which raw skins and hides are converted to a durable and flexible material which is non-putrescible. The cost of the new system is higher but can be compensated with the environmental benefits by eliminating chrome in leather manufacture. The tara-silica combination tanning system also resulted in leathers with good buffeability and hence the leather made from this tanning system is also suitable for the manufacture of suede leathers especially for upper. Therefore the tara-silica combination tanning is a good tanning system for the manufacture of upper leathers. Skins stabilized with tara - silica combination tanning could be adapted to shaving readily most important is that it would not produce wastes containing chromium means it is zero chrome discharge because chromium is not used in this tanning system. Physical testing and organoleptic properties of the matched pair leathers of the tara-silica combination tanning system were comparable to that of chrome tanned control leathers. In general the characteristics of the leathers obtained by tara- silica combination system provides leathers with good organoleptic properties and comparable physical strength for upper leathers. In contrast, pre-tanning with masked sodium metasilicate resulted in leathers with poor organoleptic properties and less hydrothermal stability. Among the combination system evaluated, leathers obtained by vegetable (Tara) pretannage followed by retannage with masked sodium metasilicate were observed to be stronger, fuller and better general appearance with the durable characteristics. Tanning system with tara followed masked silica gives resulted in wet white leathers with shrinkage temperature of 80oc. The order of addition of silica and tara, amount of tara and also the type of masking agent had a significant influence on the shrinkage temperature, physical strength and organoleptic properties of the leathers produced. The combination tanning based on silica and tara were optimised for the amount of tara, order of addition and masking salt used for the preparation of silica tanning agent. Silica remains in solution at a narrow pH range and hence in order to keep the silica in sol at pH of about 3, silica tanning salt was prepared by masking with salts viz., sodium citrate and sodium tartrate. This tanning system eliminates the use of chromium in tanning process thereby environmental impact of chromium can be avoided.
#Tanner chemical burns chromium sulfate free
Consumer awareness and short coming of chrome tanning system calls for a need for the development of chrome free tanning, Hence this research work is focused on, the development of silica and vegetable tanning agent (Tara) combination tanning system as an alternative to chrome tanning.
Chrome is the well-established tanning system adopted globally.
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