This paper deals with decantation washing of calcimine (limed collagen splits), one of the valuable byproducts of leather manufacturing industry, in order to remove calcium hydroxide from the calcimine inner volume. This process can be mathematically described as diffusion accompanied by desorption. The process of desorption makes the governing equations non-linear. There are two steps to perform the deliming process the first one is a simple washing of the calcimine in plain water, the second one requires adding a deliming agent. We have worked out a mathematical model that enables us to determine if it is economically and technologically efficient to perform plain water washing or chemical deliming. (C) 2009 Elsevier Ltd. All rights reserved.