Before we became involved with processing fibre, we were shocked and somewhat outraged at reported losses of between 30% and 60% and could not comprehend "what went wrong". Our understanding is a little different now. Raw blanket fibre that appears to be "clean" and free of vegetable matter, second-cuts and bits and pieces, loses between 3% and 7% weight during washing and drying. Our conclusion is that this loss is made up of sweat, urine, dust and skin oils and this is verified by specialists in the big mills.
Merino loses up to 40% weight in the scour process. If the fibre is passed through the separator, guard hair is removed – since this course fibre is heavier than the fine soft fibres, it stands to reason that a fair bit of weight is lost here too. A small quantity of fibre is left on the machine during carding and this is essentially unrecoverable other than as waste. Therefore, the larger the batch we process, the less the percentage unrecoverable will be overall.
Spinning takes a fair bit of set-up in order to get the machines working well with a particular batch of fibre. Brittle fibres, lots of slubs and shorter fibres all complicate the process and cause lots of breaks in the singles – so more loss occurs here. In the final analysis, the more consistent the fibre, a very high comfort factor and the strength and flexibility of the fibres play a significant role in the quality of the final product as well as the percentage weight loss.