In any case the mass and energy balances of a proposed process have to be considered with care and must be compared to the present state of the art processes based on synthetic dyes [9]. An extraction of plant material at the site of the textile dye house
could be accepted during the initial phase of a scale-up of natural dyeing into commercial production, on the long term the success of natural colourants for dyeing processes will depend on the availability of concentrated dye stuff formulations [8].
While the costs of plant material available from direct farming can be reduced by use of by-products from food processing and timber industry, the low dye stuff content present in plant sources causes the central problem for a re-introduction of plant material into commercial textile dyeing processes. As an estimate, for dyeing
of 1 kg textile material a dyer will have to process almost the same amount of plant material during dyestuff extraction. From cooperation projects with technical dyehouses this situation was identified as a key problem to be solved before a wider application could be considered [10,11].