Environmentally sound-the manufacture of dog-chews

摘要

Dog-chew products are an excellent way of adding value to lime splits. This is especially so when the flesh splits represent a high proportion of the splitting yield. Although the prime focus should be on the grain split for leather, the pieces being converted into chew products need to be uniform. The optimum final substance is 2.0-2.5 mm, so the limed splits often need resplitting to approximately 3.0 mm. With very thick hides, such as buffalo, this means that in addition to the grain split, several uniform pieces can be provided from each hide. Whereas a prime function of deliming in leather making is to release protein from the hide to ensure softness, with dog-chews these proteins can be retained. This not only increases the final weight yield, but also minimises the environmental load of any waste waters. Hydrochloric acid is therefore used to a pH of around 7.0 as this provides a clean appearance. This can be supported by the bleaching action of hydrogen peroxide, also used to oxidise free sulfide carried over from unhairing. Dog-chew products are part of a very competitive market, so it is critical to make maximum use of the raw material. The accuracy of cutting, and use of waste materials in higher value products, cannot be attained by working from die wet condition. Consistency can only be ensured when the delimed/bleached pieces have been taken to the dried state.