Cooley's Cyclopaedia of Practical Receipts Volume I Part 96

_b._ They are tacked together endwise either by hand or a machine, so as to form one continuous piece of 300 to 350 yards in length, according to the weight of the cloth.

_c._ They are singed.[213]

[Footnote 213: Generally on one side only; but for goods to be subsequently finely printed, on both sides. For very fine printing the nap is sometimes removed by shearing instead of 'singeing,' an ingenious and effective machine being employed for the purpose.]

_d._ They are crushed into a rope-like form by drawing them through a smooth aperture,[214] the surface of which is generally of gla.s.s or porcelain--the rope-form being given them to enable the water and other liquids to penetrate the goods more easily, and to allow them to be laid in loose coils in the kiers.

[Footnote 214: Such apertures are also used instead of pulleys, in the transfer of the rope from place to place.]

2. The pieces are bucked or boiled in milk of lime[215] for 12 to 14 hours,[216] followed by rinsing or cleansing in the was.h.i.+ng-machine.

[Footnote 215: The common proportions are about 1 lb. of quick-lime slaked and reduced to milk, with 2 galls. of water, for every 14 or 15 lbs. of cloth.]

[Footnote 216: This is done in a large iron boiler furnished with a perforated false bottom of wood, and technically termed a 'kier.']

3. They are soured in water acidulated with hydrochloric acid,[217] and again washed; similar machines being employed for each.

[Footnote 217: This dilute acid or acidulated water has usually the sp.

gr. 1010 or 2 Twaddle.]

4. They are bucked or boiled for 15 or 16 hours in a solution of resinate of soda,[218] and then washed as before.

[Footnote 218: Made with about 17 _lbs._ of soda-ash and 3 _lbs._ of resin, with water, 50 galls., to every 20 or 21 _lbs._ of cloth.]

5. They are chemicked by being laid in a wooden, stone, or slate cistern, when a solution of chloride of lime[219] is pumped over them, so as to run through the 'goods' into a vessel below, from which it is returned on them by continued pumping, so that the cloth lies in it for 1 or 2 hours; it is then washed.

[Footnote 219: Technically called 'chemick.' The strength of the solution is usually of the sp. gr. 10025, or 1/2 Twaddle.]

6. They are bucked or boiled, for 4 or 5 hours, in a solution of 1 _lb._ of crystallised carbonate of soda, dissolved in 5 galls. of water, to every 35 _lbs._ of cloth; and washed.

7. They are again 'chemicked,' as before; and washed.

8. They are soured in very dilute hydrochloric acid;[220] and then left on 'stillages'[221] for 5 or 6 hours.

[Footnote 220: Sp. gr. 10125, or 2-1/2 Twaddle.]

[Footnote 221: Low stools or props to keep them from the ground.]

9. They are, finally, thoroughly washed, well squeezed between rollers, dried over steam-heated tin-cylinders, starched or dressed, and finished.

This is the usual process for good calicos, Muslins, and other light goods, are handled rather more carefully; whilst for commoner ones the sixth and seventh operations are generally omitted. The whole usually occupies 5 days; but by using Mr Barlow's high-pressure steam kiers, it may be performed in two days. Yarns, &c., may be bleached in a similar manner by first looping the skeins together.

_Obs._ According to the most reliable authorities, the strength of cotton-fibre is not impaired by its being boiled for two hours in milk of lime, under ordinary pressure, out of contact with the air; nor, according to the bleachers, even by sixteen hours boiling at the strength of 40 _lbs._ per 100 galls. It is said that lime is less injurious than 'soda.'

Solution of caustic soda, sp. gr. 1030, does not injure it, even by boiling under high pressure; but, in practice, soda-ash, or carbonate of soda, is used, and this only in the second bucking, and in the third, if there be one. The strength now never exceeds 25 _lbs._ of the crystals to the 100 _galls._, and is usually less.

Experiments have shown that immersion for 8 hours in a solution of chloride of lime containing 3 _lbs._ to the 100 galls., followed by souring in sulphuric acid of the sp. gr. 1067, or for 18 hours in acid of 1035, does not injure it.

By the improved method of previously treating the goods with lime or alkalies, little chloride of lime is required. Indeed, it is said that where 300 _lbs._ were formerly employed, 30 to 40 _lbs._ only are now used. At the same time it is right to mention, that though a solution at 1/2 Twaddle is usually regarded as the best and safest strength, yet in some bleach works, particularly for inferior and less tender goods, this is greatly increased, even up to 5, the period of immersion being proportionately reduced, as it is not safe to expose the goods long to the action of such powerful solutions. With the higher strengths they are pa.s.sed rapidly through the liquid with the calender, sufficient time only being allowed to soak them thoroughly; then immediately through the acid or souring, followed by was.h.i.+ng as before.

In Scotland and Ireland the was.h.i.+ng is generally performed by wash-stocks; whilst in Lancas.h.i.+re, dash-wheels, or was.h.i.+ng machines with squeezers, are almost always used for the purpose.

Cotton loses about 1-20th of its weight by bleaching.

II. BLEACHING of =Linen=:--Linen may be bleached in a similar way to 'cotton,' but the process is much more troublesome and tedious, owing to its greater affinity for the colouring matter existing in it in the raw state. Under the old system, several alternate buckings with pearlash or potash and lengthened exposure on the field, with one or two sourings, and a final scrubbing with a strong lather of soft soap, const.i.tuted the chief details of the process. In this way a high degree of whiteness, though not an absolutely pure or snow white, was ultimately produced. Gra.s.s-bleaching or crofting is still extensively used for linen; but it is more generally employed only for a limited time, and in combination with a modification of the system at present almost universally adopted for cotton goods; whilst, in some cases, crofting is omitted altogether, and the bleaching conducted wholly by the latter process. The following _Tables_ exhibit the outlines of the new system as at present practised in Ireland and Scotland:--

_a._ For plain sheetings:--

1. They are bucked for 12 or 15 hours in a lye made with about 1 _lb._ of pearlash (or soda-ash) to every 56 _lbs._ of cloth, and washed.

2. Crofted for about 2 days.

3. Bucked in milk of lime.

4. Turned, and the bucking continued, some fresh lime and water being added; and washed.

5. Soured in dilute sulphuric acid at 2 Twaddle.

6. Bucked with soda-ash for about 10 hours, and washed.

7. Crofted, as before.

8. Bucked again with soda-ash, as before.

9. Crofted for about 3 days.

10. Examined, the white ones taken out, and the others again bucked and crofted.

11. Scalded or simmered in a lye of soda-ash of about only 2-3rds the former strength, and washed.

12. Chemicked, for 2 hours, at 1/2 Twaddle, washed, and scalded.

13. Again chemicked, as before.

14. Soured for 4 hours, as in No. 5; washed, and finished.

This occupies 13 to 15 days, according to the weather.

_b._ For s.h.i.+rtings, &c.:--As the preceding, but with somewhat weaker solutions.

_c._ For goods to be subsequently printed:--

1. Bucked in milk of lime for 10 or 12 hours.

2. Soured in dilute hydrochloric acid of 2 Tw., for 3 to 5 hours, and washed.

3. Bucked with resinate of soda for about 12 hours.