Hank scouring machines

For worsted yams, scouring can be conducted at a maximum temperature of 60 C for 30 min with 1 g/1 non-ionic detergent and 0.5 ml/1 acetic acid (80%). Woollen spun yams lubricated with oleine are scoured at 30 C with soap or synthetic detergent and sodium carbonate. The addition of solvent is sometimes advantageous for the removal of oils. Tape scouring machines are generally used for the scouring of hanks. 

Scouring machines of wool depend on the kind of wool to be scoured i.e. raw wool, hank form or woven fabrics. Scouring of wool can be carried out in batch or continuous process, aqueous or solvent media and rope or open width form. 

Woollen and worsted yams, unless dry spun contain significant amount of lubricating oil and are usually scoured in hank form in a continuous scouring machine. The hanks are transported through the scouring sets either by tape (Fig. 5-21) system or by battrices (Fig. 5-22). Usually, the sets have four bowls two scour bowls, one rinse bowl and a final bowl where acidification and moth proofing is carried out. There is a pair of squeeze roller between each bowl. The top roller is usually lapped with wool or cotton sliver and the bottom roller is made of metal. Pressure is applied to have an expression of about 60%. The characteristic features of the two types of machines are summerised in Table 5.2. It is normal to scour only 1-2... 

Hanks are mercerized on a machine of the type illustrated in Fig. 3.15, although there are many other designs. The hanks, which have been scoured previously, are placed over arms which apply tension. They then rotate the yarn, at the same time themselves moving in an arc to immerse the cotton in a caustic soda solution of specific gravity L3, equivalent to 27 per cent concentration. After a few minutes the arms move to another position, where the bulk of the alkali is rinsed out before tension is removed. A further movement accompanied by relaxation of stretch permits removal of the hanks, which are then rinsed in acetic acid and thoroughly washed T with water. A mercerizing machine for open-width cloth is shown in g. 3.16. 

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