All fleece needs scouring, unless it is going to be hand-spun in the grease and washed later. Scouring removes dirt, impurities, extraneous matter (such as barbed wire!), and of course lanolin. White lanolin goes into cosmetics, brown lanolin from the coarser fleeces into prawn food in the Far East. There are two major scouring plants in the UK, both in Bradford, with a handful of much smaller plants elsewhere in the UK and Europe. Environmental pollution controls are very strict. Australia and New Zealand no longer have major scouring plants as all the processing is done in China.
First stage of scouring
The first stage of scouring involves tearing the fleece apart to release the dirt, especially that which is held in the tip of each lock. This Pirhana machine rips apart cotty (matted) fleeces.
Scouring baths
The scouring process itself consists of four gigantic baths descending in temperature.
The first picture above shows you the ascent to the first bath, which is at a minimum temperature of 65 degrees C. The fleece comes out of the first bath (several tonnes of it), is squeezed, and the sludge is used as rhubarb fertiliser. It then passes to the second bath (as in the second picture) where detergent is added. The third bath is used for rinsing, and in the fourth, bleach, which works best at 41 degrees C, is added if necessary.
The next stage is drying. Lower heat is used for finer wool such as merino, more for coarser wool such as Welsh Mountain, and with variations for other types of wool. This whole process takes about 16 minutes and was how our Exmoor Horn fleece was scoured on an industrial scale. Any fleece going on to further processing such as spinning, will undergo this cleaning (whatever the end product) so that machinery does not become clogged with grease.
However, our 4ply yarn was scoured in a cottage-industry manner. 30 Exmoor Horn fleeces were scoured 5 at a time using the same principles as in the large-scale operation. The timescale was significantly different at four-and-a-half hours per 5 for washing and up to 14 days for drying, in other words several weeks’ work.
The pictures show a series of baths from initial immersion of dirty fleeces , through detergent addition and successive rinses to drying on suspended wire frames to facilitate air flow.