144 EVANS-" TRIOINDIGO COLOURS IN CALICO PRINTING." 1hln.y. 1815.

settle. He was glad to say that in Bradforc in their strikes they showed reason, because th , men on both sides were practical men anc understood their business. There had been nc heated feeling, no disturbances, no riots. Jusl in the same way as that had been done locally he held it they could be done nationally. The] must not say that the problems of the two great forces, capital and labour, must be solved b j the Government. They must say that these questions could be settled by the people inter- ested, with the full knowledge that evcry one of them was dependent upon the others. They must be fair to one another, must recognise one another's lives, must recognise that the nation was made up of all kinds of people, and that no man and no class had exclusive rights.

MANCHESTER SECTION.

Meeting held on March 14th, 1913, Mr. W. H. PENNINGTON in the chair.

Thioindigo Colours In Calico Printing.

By NORMAN EVANS.

The Thioindigo dyes now constitute a good range of vat dyestuffs, the earliest of the series, Thioindigo Red B, having been introduced in 1905. They are all similar to Indigo in that their application depends upon their reduction to characteristically coloured, alkali-soluble leuco bodies which are absorbed by the fibre in either dyeing or printing, and by subsequent oxidation are converted into the original dye- stuffs. The Thioindigo dyes are now of con- siderable importance in each of the three styles of calico printing, viz. :-(a) Direct printing, (a) discharge work, and (c) resist work.

I n Direct Printing the conditions to be aimed at are necessarily a maximum reduction of the colour with a maximum absorption of the leuco body by the fibre. These conditions vary with each individual colour. Of the various possible reducing processes there are, however, only four or five which give satisfactory results with all or most of the colours, ant1 which are therefore of practical interest.

The printing paste contains a suitable thick- ening, the dyestuff and the reducing agent, or, alternatively, the dye may be applied by merely printing a caustic alkaline thickening on cloth prepared with glucose. Indigo has been printed for a considerable time by this process, which is known as the Schlieper-Baum process (after its inventors), or the glucose-caustic process. After printing, the goods are dried and steamed in the air-free rapid ager, after which they are oxidised and finished by soaping.

The thickenings employed depend upon the nature and amount of alkali required in the reduction of the dyes. With the exception of rice starch, starches caiinot be used satia-

factoril , and British gum is generally recom- mendeJ whilst various other thickenings, such as gum senegal, gum arabic, are quite satis- factory when not too expensive.

The reducing agents chiefly uscd are hydro- sulphite N F conc., sodium hydrosulphite, and glucose. In some cases stannous oxide gives good results, but owing to the detrimental action of this printing colour on doctors and rollers, it is not of any practical impor- tance, and hydrosulphite is the principal reducing agent cmployecl. The alkali used is caustic soda, sotli um carbonate, potassium car- bonate, or potassium sulphite, according to the colour. The different combinations of assistants and reducing agents give rise to the following processes :- Hpdrosulphite - caustic ; glucose-caustic ; potassium sulphite ; hydrosul- phite-soda; hydrosulphite-potash; bicarbonate; glucose-carbonate. These various methods do not work satisfactorily with all the colours in the range, but with the exception of the glucose- carbonate process. they are, however, all of technical importance.

Caustic soda, although i t is largely used and gives very satisfactory results in manv cases, is objected to on account of the causticity it imparts to the back greys.

Hydrosulphite - Caustic Process.-This works well with most of the dyes, but especially so with Thioindigo Red €5, Thioindigo Scarlets 2G and S, and Thiointlone Yellow 3G. By this method the Thioindigo dyes may be printed either alongside OP in combination with Indigo.

The amount of caustic soda required for the various printing colours for full shades varies from 5 per cent. t o about 55 per cent. a t 90" Tw.

Glucose-Caustic Method.-This consists of print- ing with a strongly caustic alkaline thickening on to cloth which has been prepared by padding with a 20 to 30 per cent. glucose solution (accord- ing to the depth of the shade required) and dried. After printing, the cloth is dried quickly to prevent formation of carbonate, then steamed for 1-1h minutes in a moist air-free ager a t 100"-102" F., oxidised, and soaped. Indigo is extensively printed by this method, and Thio- indigo dyes may be applied in conjunction with it. The colours which print better by this method than by any other process are Thio- indigo Scarlet It, I'hioindigo Blue 2GD, and Thioindigo Grey 2R.

Potassium Sulphite Process -This consists in printing pastes composed of dyestuff, thickening, hydrosulphite NF' conc., and potassium sul- phito with or without an alkaline amistant, such as caustic soda, which, when used, varies in amount from 3-13 per cent. a t 90" Tw. In general i t is found that where potassium sulphite is effective, camtic soda may be used in much smaller amount if not actually dispensed with. Similarly the quantity of hydrosulphite NF conc. can be lessened owing to the reducing action of the potassium sulphite. The process gives with a number of the Thioindigo dyes better results than are obtained from the

May, 1813.1 EVANS--" THI0iNI)IGO COLOITRS IN CALICO PRINTING." 145 - ~- -

strongly alkaline printing colours, and it is particularly suitable for Indigo K2B, KG, Thioindigo Red BG, Thioincligo Pink BN, and Thioindigo Violet 2B.

Hydrosulphite-Soda Process.-The printing paste contains the dyestuf-f, thickening, hydro- sulphite N F conc., and carhonate of socln.

Hy~rosulphitr-Potnsh Procrss.-The paste con- tains carbonate of potash in place of the soda These two methods are not equally suitable for all the dyes, as will be seen froin the table The printing colonrs are quite harniless to back greys and blankets, and in consequence these processes are valuable. They possess, however, the disadvantage that Indigo will not priut satisfactorily by thcni The hytlrosulphite- soda process is particularly suitable for tho Thioindigo Pinks, Thioincligo Scarlets C: and 8, Thioindigo Red 3R, Indigo BBB, and Thio- indigo Violet K, whilst the hydrosulphite- potash method gives good results with Thio- indigo Scarlet 2C$, Thioindigo Orange R, itlid

Thioindigo Grey 2B. The Bicnrbowlc Process, which has only I)ecn

proposed during the last year, is ititcresting ; ~ n d important. It consists in the 1)reparation of a thickened vat prepared with hytlrosul~~hite conc. powder, to which is then added hydrosulphitr N P conc. and bicarbonate of soda. The printing is done in the usual way. Its results are of the greatest importance, for, a s will be seen from the table, i t prints well with nearly all the colours, and gives fuller shades in many cases than are obtained by any other process I t also possesses the itdva.iitagc of being free froin objectionable causticity. The principle of the process is the conversion of the catistic alkali necessary for the reduction of the colour into the nornial carhonate by the snbsequent addition of socliu i n bicnrbonatc ; adding hydrosulphite Nli' coiic. to keep the printiiig colour in proper condition for the steaniing It is surprising that the results obtained froin a printing colour ])repitred in the iiiariner des- cribed arc so much superior to those froin the hydrosulphite-soda process, and the explanation can only be tha t the us0 of hydrosnlphite conc. powder reduces the colour niore conipletely before steaming. This process gives better results than any other process with Thioindigo Reds BG and 3R, Thioincligo Orange R, Thio- indone Green C. Indigo K2B and KG, Tliio- indigo Violets K and 2 R , 'I'hiointligo Hrowiis G, R ancl 3R, ancl work8 well, but is a little inferior to other processes, with Thioindigo Scarlet It, Thioindone Yellow 3 0 , Thioindigo Blne 2CD, and Thioincligo Scarlet 2G. It should also be mentioned that Indigo prints very well by this process, though the results are a little inferior to those obtained by the usual methodr.

From the comparative tests of the difforent methods for printing Thioindigo dyes, it is noticeable that every colour can be succesvf ully printed by either the bicarbonate process or the hydrosulphite-soda or hydrosulphite-potash pro- cesses. In consequence of this, every Thioindigo

__-.pp-- ~ ~~

dye can be used by a method liarinless to back greys and blanltetr.

In preparing the printing colours, i t is ad- visable to observe the details mentioned in the rirciilars of the niakers, antl pitrticularly so regartling the temperature for the reduction ; this being essential to the uniformity of the 1)rints

When the printing colours contain caustic ztlkali it is atlviqable to clry the printed cloth its qnickly as pos4ble to avoid the formation of carbonate, which with sotile colonrs would iininir thc results Excess of heat is to be iLvoitlet1 The drying inap be tloiie in the hot flue or nioro conveniently 011 cylinrlcrs. 'l'hc colour is then fixed by steaming in the air-free ager, which decoiiiposes the hydro- rulphite &c. The best conditions for the fixation of a colour can only be determined bv priwtical trials. The steaming temperatures vitry between 100"-110" C ,for whilsttheiiiajority of the colotirs fix perfectly Iwtween 100°-1050 C.,

L coniplcto fixatioii o f 'l'hioiiicligo lted B indigo Scarlet I t A temperature of

itbollt 105"-110" C! is requirccl. For the fixation of some of the colours tho presence of moisture is esscntial, aiicl this is supl)lietl by an addition of glyccrinc to the printing colour. In steaming, time is a great factor, ant1 a too r;LpitL pawage through the ager only partinlly fixes the colour. Generally speaking, five minutes' steaming at thc teniperstures given for the different colours is sufficient If the tenilwrnture is higher than tli:Lt reconiinciitlccl, the tliiration of the ageing citn be lcesenccl, or siniilarly it may be prolonged should tho teinperature tw lower than ])re- scrihctl

After stenming, the goods itre oxitliscd b v a verg thorough rinsiug with cold watcr, or by 1)aqsing through it slightly ac tlilute birhromate bath, or by a 1) R weidi solntion of sodinni Iwr1)i)r:tte. In the case of goods priritetl with Thiointligo Itecl B ant1 8carlct R, a bleaching pow(lcr solution of about 4'' 'L'w. ir employed for oxidiring the coloiir, this trettttnent (leveloping thr colour and clearing the white ground a t the si~inc time The use of the bichrninate btLth is not always itrlvis- able, since in some cases the shatlex are affected thercby, 1)ecooiing yellower antl conritlerahly duller. 'l'liis is the c a ~ c with Indigo K2B, l i U , ant1 Y'hioincligo Scarlet 2C:. With the latter it is advisttble to oxidise by hanging ovcruight beforc riribing After the complete oxidation of the colours they are rinsed in cold water atid then soaped a t the boil, excepting 'I'liioindigo Red €3 aiid Thioindigo Scarlet R, for which soaping, if done a t all, is carried out a t about 50" C. The bleaching solution treatment without any soaping produces the lxightest shacks obtainable with these two clycs. With the other colours, the greatest brightness and fastness is only obtained by twenty minutes' treatment in a boiling solution of 2-4 lbs. soap per 100 gallons.

Colniirs.

Hytlro- 8iilpliite SY ( (Oll l* .

ulld Csiist io S o h .

Thinindigo Red RQ . . Thioindigir Rrti 313 .. Thioindigo Rcarlet 2G Tliioindigo Srnrlet C;

Tliioindigo Sciirlet It

Tliiointligo Scarlet S

'I'hioindigo Pink .\N

'l'liioindigo Pnil; RN

Thioindigo Orange R Thiointlonr YvIIow 3C

Tntligo KG ... .

Tndigii Ki'lR ... .

Tliioiiitligii Grey 2B . Tliioiritiigo Violet I\: . Tliioiritligii Violet 2R Tliiointligo Rrown G

Tlii~iindigo Brown R.

Tliiointligo Brown BR

Intligci ... .

fililrC8R Prepwe'

vitlr Oaiatio r(lrla.

2 Bluer and

ilightly ,111 ller

5 5

Reddor 6 5

1

5

6

5

5

3 I h ilor

6

1

4 MlICll redder

4 Reddm

1 6 5 2

3

4

1

-

Hydro. iiilpliite $1 Colic!.

nnd qndn

Curb.

5

3 2

4 1

)

2

I

I

1

)

1

4

3

2

4 2 3 6

5

5

4

4

4 3

2 3

4

'I

4

:I

2

4

3

3

J

3

2 4 4 4

4

3

5

lytlrosiilphite so(la n n c l puttirli processes o f no intrre.it.

\I1 processek print well. -\I1 procewea print, well cs-

cq3ting glucose process.

,111 processes print well cx- cryting glucoso pro'

cesaes of no interest. [iicarbonrtte procvss by far the

I ) f t H t . Hydrosiilpliite cuurit,ir, glucose

tint1 bictwbonnto processes are good, but differ in shndes; the cttrbonatpe processrs of no interest.

Ricarbonnte ~ ) r o ( w n by far aiiprrior.

Glncoso process vcry superior ; printed with sodiurn hydro- xulpliite and p t n s l i = 8.

Hicnrbonnte process very ~ I I - pr ior .

I'otassinm sulpliitn m d bi- carbonate prooeasrn rqiially good. the latter duller.

Gliiciose process by far the Imt. Glucose process o f no interest. Glucose process of no in teerest. Hicarlxmate procras by far the

Ricctrbonitt,e process riiiicli 811- best.

perior. Hydrosulphite ranstic and bi-

-rnrhonke proressm the only uiethods of intereat.

Only little diflcrcnre hetwten hydrnsulphite cniirtic. and glncose cuuutir. Hirctrbon- n t e resiilts are ulro good. The roda and potash prorrrsrr i ) f no me. -

1 raprrsents beet results. cannot IJR u s c d by lh? process referre

6 rtyesenta poor.pst rrrults, but does not riecwsarily imply ilint tlie dye to.

SpPciial Styles -The Thioiidigo dyes print as well on P-naphthol prepared cloth as on unpre- pared clot'h, and consequently they may be applied in conjunction with Para Recl or Napht,vlsinine Bordeaux, &c. They can also be nsetl in conjunction with siilphicle dyes, and by combinahtion %ith these fuller and duller shades w e obtained. Mordant dyes may also be

printed with the vat dyes. the inoat convenient baing those which are fixed by a short steaming through the ager, such a8 the Phenochrome Browns.

111 the application of Thioindigo tlyes in conjunction with black, Aniline Black or Diphenyl Black is gen9rally used, excepting when the colours overlap. In thin case n sulphido

May, 1013.1 EVANS-" THlOlNDfUO COLOURS IN CALlCO PRINYIKG.'' 147

black, a vat black, or a black composed of Indigo shaded with Thioindigo Scarlets R or 2 6 and Inclanthrene Yellow R shoulcl be used. The Thioindigo dyes are very suitable for stencil work (squirting process).

A recent development consists in printing certain Thioindigo dyes with chrome mordants, fixing by steaming for about one hour in the usual way for mordant coiours, and finally washing, malting, and soaping By such a method Thioindigo Grey 2B. Thioindigo Browns G, R, and 3R. Indigo K2B and KG give very interesting grey ancl brown shades which are fast to light and washing, and actnally faster to chlorine than prints produced by the ordinary methods.

Thioindigo Colours in Discharge Work.-They may be used for the production of coloured discharges on any ground which is discharge- able by hydrosulphite NF conc., and the pro- cess, which is very simple, consists in adding the Thioindigo dye, along with the alkaline assist- ant necessary for the fixation of the dyestuff, to the hydrosulphite NP conc. dischargc paste, then printing, drying, steaniing in the rapid ager for about five minutes a t 100" C., rinsing and soaping. The possibility of this style lies in the fact that the Thioindigo dyes are reduced, but not destroyed, whilst thc ground colour is destroyed, and then by subsequent oxidation the vat colour is regenerated. The Thioindigo Scarlets, Thioindigo Red B, and the Indigo brands K2B and KG are used regularly in this style. With the large number of vat colours ancl suitable ground colours along with white dis- charges there are almost endless possibikties of multi-coloured effects. In using Thioindigo Scarlet 2G in this style, thc brightest and f allest reaults can only be obtained by allowing the discharge colour to stand for some hours, or even a day, before printing. Also, after ageing, the goods must be allowed to hang overnight. The soaping, which is also necessary to ohtain the brightest results, is effected at about 50" U , thus allowing for the difference in the fiistiiess of the Thioindigo dye and the ground colour.

Another discharge style depends iipon the use of Thioindigo dyes in combiliation with basic dyes. The procees is carried out by printing on cloth, mordanted, as is usual, for basic dyes, the Thio ind igo dge , h y drosul ph ite- caustic printing paste, with one roller, and an ordinary caustic white discharge with a second roller. After printing, the goods are dried, steamed in the air-free ager a t about 100"-106" U. for five minutes, and then well rinsed. Thus, whilet the vat dye is fixed, the mordant for the basic dye is destroyed. The oods are now

the usual addition of alum, after which they are again soaped and dry-chemiced to clear the white. In this style basic dyes, which give very good white effects with caustic soda, are Rerviceable, such as Fast Cotton Blues TIA, TEN, TLK, and TLR, Fast Navy Blue 3R, and Dbzine 'Blue iAE, &c.

soaped, and then dyed with the % asic dye with

Similarly, the Thioindigo dyes should find an opening as coloiirecl discharge effects uiidcr Aniline Black; in which process basic dyes are largely used at present'. C'onsiclering the great difference in fastness to light between the Aiiiline Black and the babic dyes, the vat, dyes must sooner or later be preferred. Excellent results are obtained. The application is very simple, ancl consists in printing the vat clyes on the padded Aniline Black cloth or printing the vat dyes first, then padding with the Aniline Black, and finally ageing for two to three minutes, allowing the goods to hang for a short tinie, washing, and soaping.

A further possibility is in the use of these colours as coloured discharges on Turkey Red, the discharge being effected bg stannous oxide, glucose, or hydrosulphite N F conc. and caustic soda.

Thioindigo Scarlet 2G, Orange R, and Thio- indone Yellow 3G, on account of their brightness, can be used as pigments iindcr Aniline Black, or as coloured discharges with bichroniate under Indigo. In both of these styles the colours are fixed with albumen in the usual nianner.

Any dyeing operation to be of use to the calico printer must permit a large production, and on this account the ordinary jigger, the nnder-the- liquor jigger, and the Indigo clipping niachine are not of much use. The continuous machine or the padding machine are more suitahle, the latter cspecially for lighter shades. The alkalinc sodium hydrosulphite vat is chiefly used. Thioincligo Rod B may also be used as a sulphide dye, owing to its easy reduction with sodium sulphide. This vat is advantageous on account of its great stability and cheapness. Thioindigo Scarlets 2G, G , and R, if reduced with hydrosulphite, can also be dyed from a sulphide of,aodium vat. I n the reduction of the dyes. as well as in thc dyeing, it is advisable to observe the particulars given by the makers of those colours regarding tem- perature; as otherwise the brightness and the :lepth of the shades may he impoverished. The penetration of the goods may be enhanced by an addition of Turkey Red oil, or the highly Julphonated oils, such as Piiropol, Furonal, Monopol Oil, &c., to the dyebath. An addition jf salt produces a better exhaustion and fuller ghades, but an excess prodnces dyeings less East to washing arid rubbing. In the case of light shades, the goods are ofteii padded in a vat produced by reduction with hydrosull~hite N F conc. and caustic alkali, then dried ancl steamed in the air-free ager a t about 100" C., oxidiscd, washed, &c.

Nearly all the Thioindigo dyes are discharge- dde to quite satisfactory whites, either by hydrosulphite NF conc. or by the inore recently introduced hydrosulphite CL ; by printing these with caustic alkali in the presence of arithraqiiinone and zinc white, drying and steani- ing in the air-free ager, &c. The white effects are materially improved by the addition of some llanc fixe, which acts mechanically. With

148 EVANS--'' THIO INDIGO COLOURS IN C.ALIC0 PRINTING." [May, 1913.

hydrosulphite N F conc. a passage, immecliately after the ageing, through a hot and diluted alkaline bath is indispensable to removc the leuco body bcfore it has time to re-oxidise, but with hydrosulphite C'L a leuco coinpound is formed which does not easilp re-oxidiso, and therefore the goods may be left standing a much longer time. Fiiislly, however, thcy must be passed through a warm alkaline bath, preferably silicate of sotln, to reniove the leuco

Leucotropc W conc. has recently been put on the market for the discharge of Indigo and other vat colours. This body is used as an addition to the hytlrosulphite N F conc. discharge printing colour, thus forming in reality liy(11-0- sulphite CL. An addition of zinc oxjde is very advisable, and the best results are obtained by adding a sinall quantity of soda ash. An addition of anthraquinone is essentid.

By the use of hydrosulphite ('L or N F conc , with the addition of dyestuffs such as Intlan- trhene Blue GCD, Intlanthrene Yellow R to thc discharge paste, yellow, blue, arid green effects of very good fastness can be produced.

By taking advantage of the fact that they are not dischargeable by oxidation, intcrcsting coloured effects of very good fastness can be produced by dyeing Thiointligo tlyes in con - junction with Indigo, and discharging the lattcr by the chlorate or bichroinate method in the usual manner. Similarly, white effects can be obtained by discharging the conibined colour with hydrosulphite N F conc. or hydrosulphitc CL.

Thioindiyo Dyes in IZesist Work.-The Thio- indigo dyes niay be resistcd in dyeing or printing by the same resists which serve for Indigo. These consist of various acid-reacting izietallic salts, such as sulphates, nitrates, acetates, chroniates, and chlorides of lead, zinc, copper, &c , which are suitably thickened with gum, with an addition of an insoluble plastic niatcrial, such as China clay, to make the resists still inore effective. By such ineails i t is possible to obtain white or coloured effects in either dyeing or printing. By combining, for instance, the broininated rntligos, s w h as Indigo K2B and KG. with Indigo. sky ant1 dark blue effects can be obtained, which on account of the Indigo K2B and ICG bciilg brighter than Indigo itself, are inore plrasing than the style done with Indigo only. Rv printing the reserve first, then dyeing in the dipping niachiiie with Indigo, reprinting a further reserve, and dyeing again with Thioindigo dyes (red, scarlet, &c.), very interesting effects may be obtained.

I n Continental printing centres, resist work under the vat dyes (blue principt~lly), in coin- biniition with a developed Para Red, has been made use of for ii number of years. The cloth is padded with /j-naphthol, priiited with the white resist of metallic siilts with one roller, and the white resist containing an addition of tliazo-paranitraniline by a second roller. By suoh means red and white effects are obtained,

boay.

-

and then the goods are dyed with the desired vat colour, e g., Indigo K2B and KG, in the dipping machine, thus producing red and white effects on the blue ground.

Another style with Para Red is the application of the Indigo K2R and KG and Thioindigo Blue 2C: as colourecl resists. The coloured resist, composed of the vat colour and the dknlinc reducing agent, with an addition of potassiuin sulphitc, is printetl on the /j-naphthol prepared cloth, which is then dried and ste:tniecl, stid finally, hy coupling with a solution of diazo- paranitraniliiie, red and blue effects (with white if desired) are obtained

A furthcr resist, staylo in which the Thioindigo colours arc 1m%icularly useful is known as " Battick Dyeing." This style consistrs of the ~~rodtictioii of variously coloured and iriarbled effccts by incans of dyeing over a wax or resin resist,, which is then purposely broken and the process repeated with some other colours. The dyeing is clone in the dipping vat, and care is taken that the temperature i s not sufficient to melt the resist. Finally, when required, the wax is removed by boiling water with an ad- dition of soda if necessary.

Reserve Salts W lrnd 0.-Both of these reserve salts act as oxidisers, and in consequence resist the fixation of thc reduced vat colonrs. Reserve Salt W produce4 white effects, but Reserve Salt 0, when nsetl iuitler strongly allraline printing pastes in conjunction with Reserve Salt W, [Jroduces an orange effect of good fastness to light and washing. Their kpplication involves printing the thickened solution of the resist, drying a d overprinting with the l'hioindigo or other va t dye, or even padding in somewhat weak vats. In either cane, the usuitl drying and stcaining is carried out. In printing, both products are effective, whether overprinted with the hydrosulphite printing colour or 1)rinted on the glucose prepared material, followed by the overprinting with the strongly alkaline printing paste of the colour. The possibility of using Reserve Salt W for resisting the fixation of the vat colours on the back greys may be nientionecl. Reserve Salt W may be also applicd i n resist work to produce coloured effects of great variety by using it in conjunction with various mordant colours under the Thioindigo rlyrs and Indigo. It is necessary that the iriorclarit colour should be well fixed by the short steaming usual for thc vat dyes. Fast Printing Green with iron and Reservo Salt W gives an excellently bright and fast green, whilst the Salicine Yellows, Salicine Orange D, the Phenochromo Browns, Modern Violet, Indigo Salt T, &o., permit the production of various other interesting effects with Reserve Salt W nncler the Thioindigo dyes. Mordant dyes, snch as Alizarin Red, requiring the usual long steaming, can also be used, but their application is not so convenient.

Fastness o/ the Thioindigo Co1ours.--From the calico printing point of view, the points of chief importance are the fastness to light, washing,

May, 191S.I EVANS--" THIOINDIGO COLOURS I N CALICO PRINTING." 140

(1) No change by the boiling. (2) No change by the treatnient iiear the boil,

(3) Slight bleeding at 48" C. i.e., 72" C.

_ _ ~ _ _ ___ _ _ -

chlorine, and to the hot iron. With regard to tht latter. every member of the range is satisfactory With reference to chlorine, whilst the colourr vary in their fastness, from a printer's point oi view the range is very satisfactory in th i i respect. The Thioinctigo Scarlets and Reds Thioindone Yellow 3G, Thioindigo Orange R Thioindigo Violet K, and Thioindigo Blue 2G are excellent ; but Tihioiridigo Violet 2R, Indigt K2B and KG, and 'l'hiointligo Grey 2K arc somewhat affected by a ~~rolongcd treatnient but their fastness is snficieiitl to withstand bleaching when caref iilly effccted. Practically the requirenients are that the goods should stand a chlorine treatment for clearing pur- poses, and also the laundry requirements, which today are somewhat severe.

Fastness to washing is of iniportanw when Thioiiidigo dyes arc irsrtl for shirtinqs which will, of coiirse, be subjected to launtlry washing, i e., boiling for a short time with alkali o r soap. In general the Thioindigo dyes, like all vat dyes, are perfectly satisfactory in this resl'ect. In the table, the respective fastnesses of the various colonrs are given. The fastness to washing has been deterinined by the following tests, (1) implying very good fastness and ( 5 ) the most affected.

Washing Tests.- The dyed yarn plaited with white cotton and wool is treated for half a n hoiir boiling, or a t 72", 48", or 36" (1. in a solutiou of 5 parts soap arid 2 parts soda per 1,000 parts liquor. The numbers imply .-

:ertain vat colours by soaping had been ex- plained by Scholl. In view of a statement made at the reading of a paper by Mr. Jones before

Tlrioiridigo Red 13 . . , Tliiointligo Red SH ... Thioindigo Red HG ... Thioindigo Scarlet G. .. 'I'hioindip Scarlet 2G Tliioindigo Scarlet, R Thioindigo Scarlet S Tliioindigo Orange R Ttiioindone Yellow 3G rndigo Ii2H ... ... Indigo KG ... ... Tliioindigo Violet 213. .. Thioindigo Violet I( ... Tlrioindigo Brown G Thioindigo Brown R Thioindigo Brown 3R Thioindigo Pink AN Tliioindigo Pink BN Thioindone Green G . . . Thioindigo Blue 2GD Thioitidigo Grey 2B . . .

(4) Noticeable bleeding a t 36" C.

DISCUSSION.

Prof. Kiiecht said the Lecturer had nientioiied

this Society last session, he was inclined to

that different vat colours required variation in methods of dyeing, and asked how this would influence the production of four or five different colours in calico printing. A further incon- venience was that the vat colours were not generally so readily miscible with one another as 3ther classes of colours. The development of

Fuslness to light is a niatter of great import- ance. Here, again, whilst thc fastness of the different dyes varies in this respect, in general it may be termed very good. There is a striking exception in Thioindigo Scarlet S, arid this product is not recorninended where fastness to light is iinportant Light fastness is again a niatter of comparison, Hntl in niaking the fastness table the makers of the colours have adopted the following tests, classifying the colours as before from 1-5.

The dyeings in niediuni shades were exposed for four weeks under glass to a south light in the summer.

(1) Scarcelynoticeable change after four weeks. (2) Slight diminution of the depth of the

shade or slight change of the tone after four weeks.

(3) Distinctly noticeable change of the depth of the shade or change of the toile after 14 days.

(4) Considerable change in shade after eight days.

(5 ) Considerable change in shade after 1-3 days, and bleaching after 2-4 days.

The numbers imply :-

Mr. Rawson and himself inally years ago. Two very interesting points were raised by the Lecturer, viz., the usc of hicarbonate in direct printing and that of reserve salt for obtaining resist effects with the vat colours. Was the action of the reserve salt that of an oxidising agent 2

Mr. Jones asked a t what period of the year the light exposure tests were made.

Mr. Schwabe inquired whether the Lecturer considered the UYO of glycerine in the colour to be the most suitable nieans of obtaining moist steaming conditions and if, in other caws, where spccially moist stenin is intro- duced into the ager, the Lecturer had made any observations as to the best temperature, both on wet and dry bulb thermometers.

Thc Lecturer, in reply, said that it was possible to use certain colours together in printing, but he did not think four or five

culours would be required to be printed together vcry freqriently. The lwightening action of soap was most probably due to it,s having R stripping effect. With r6gard to oil tlctrncting froin the fastness to light. he thonght this referred to the action of oil introduced afber dyeing. and not as an addition to the vat. He hatl not niiide any experiaients on the effect of copliering, but Meister, Lncius & Rriining rcwomniended copper- ing in one case. but in ninny eaneb its value was innch diniinished owing to the fiict that it iiiudc the shnde d r i l l . In order t,o 1)c cfkctive, reserve Hidt rrqriiretl steaniing. The cspcisure to light test was niadc during ladt antnnin He hatl no expcrience as to the ainount of moisture iinparted to cotton 1)y glycerine.

Mr. Ituwson proposed and Mr. Browulie seeoutled ;L vote of thanks.

Note on Manganese Bronze as an lntensificr and Restrainer under Vat and Sulphide Colours.

By EDMUNLI KNECIXT.

It has been known for a. long time that nianganese bronze dyed or printed in the ordi- nary way on cotton iinparts to the fibre the property of taking up much larger qn;intities of Indigo from thc vat than it otherwise woultl do. By a subsequent treittnient of the fabric with a suitable reducing agent, such as bisnl- phite of sotla, tho iiii~iigane~e broiizc is rcinovetl, and the intensifying effect hecoiiies apparent. The cxtr;l amount of Indigo fisccl on the fibre would y q ) c w to depend upon the strcngth of the ni:ingtLncsc bronze Iircviorisly clyctl or priiitetl, so that it is possilr)lr, I)y printing mrioiis strengths of niaiigimcsc I)ronze. to obtain l)y i~ single ‘‘ dip ” varioris depths of blue on i~ IigliL l) luc~ ground. If i~ wtix resist I N Iirintotl on tis well, a white, iilollg with vuriow shutles of b l i i c ) , results. For i L (lark blue ground the process may be altered so that the whole piece is dyed a niaiiginese hronzc in the ortlinwy W ~ L J J , then tlischargctl in the tlcsirctl puttern with stiiIlliotis chloride, i ~ n d then tlycd in the vitt.

I n spite of the advantages to be g;Liiicd by the use of snch intensifiers in dyeing, tht’ ’ir use on a practical scale ap1)ear-s to be vcry liniitecl, arid this is no doubt due to the extra cost in- volved by tlie adtlitioiial ollerations, siiiiilai results being obtainable niore economically by other nicthods.

If the mimganese bronze is riot foriiicd 011 the fibre, but is printed i n the condition of 1igtlratc.d peroxide of ninngitnese, suitablj thickened, it acts in csactly the opposite manner ; i e , as a restrainer, or even as a resist. It should thus be possible, by the use of cne and the same reagent (but this could obviously only be clone in block printing) to obtain IL white aiicl a dark blue 011 u light blue ground in one dip

l)henonieiiit has not to iny knowledgo beei A tlicwrcticul C’Sl)lihliiLtioll of thl:HC r(~lliiLrkiLbl<

hitherto ittteniptetl, but wonld a t first sight not be far to seek. In the case of a nianganesc bonze fixed on the fibre in the ordinary way, mc might imagine that the hydrated perositle /present on arid in the fibre wonld give I J I ) the whole or part of its available oxygen to the Indigo White, thus precipitating Indigo on and in the fibre. If, 011 the other hand, the thickened hydrated peroxide were printed on to the fabric, ziicl the dyeing proceeded with, the Indigo White woultl be osidisetl to indigotin, and thiis rcndere(1 insoluble before i t reiichcd the fibre, r~nd dyeing would either not take plucc a t all or only to a small extent.

Possibly the action of the risu;ll restrainers or resists under Indigo,* which contaiii salts of copper or flowcrs of sulphur as their active constituents, might be cxplaiiicd in a similar way. In those easeh, however, the salts or the acids contained in the resist probably assist in its action.

But in view of the results obtained on calico print,ed nianganese bronze, ant1 then dyed with other vat dyes, thc simple exlhnat,ion of tlic intenflifyiiig action of the bronze given iibove evidently cannot hold good throughout.

By t~nalogy it might reasonably have been expected that other indigoid dyes would behave in dyeing like Indigo, and yield darker shades on the inangaiiese bronze dyed poftions of the fabric. Thus, Thioindigo Red behaves like Indigo, but, if anything, the intciisifying action of the initrigaiiese bronze is niore iilitrltctl with this dyestuff than with Indigo. With Thiointligo Scsrlet the effect is soniewhat less niarkctl than with Thiointligo Red or Indi&o. On tlie other hand C‘iba Rlue dyrcl under itlcntictil conditions 011 thc w n c niatcriiil i u resistcd by the inan- gtxnese bronze.

With sonw coloiii~s of this class (e g., Helin- tloitrb Rccl 313) thv Iwroxitle seemed to csert no c+Tcot either one way or the other.

In these expcriiiients both the hydrosul~ihite a i d the zinc vats were tried, but, generally the latter p v e bet8ter results.

With the sulphide colours, which in a+ sense nicty be considered as vat colours, siiniltir tlis- crepancies were observed. Thus, whereas the iiiariganesc bronze acted as an intensifier for smh colours as Eclipse Green G, and especially for Iinniedial Sky I3lue, its action on other colours of this elms, such as Katigrnc Black, Thionol Blue, and Hydron Blue, wax that of a restrainer. These differences are especially markecl in the cases of Immedial Sky Hlne and Hydron Blue.

In these cases the ordinary sulphitle colours were dyed from B socliuni sulphide bath, while the Hgdron Blue was dyed from a hyclrosul- phite vat.

With the colouring matters of the Tndanthrene aricl Algole series, the manganese bronze did not act as an intensifier on any of those that wcro

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* Hce .Il.io ‘L’he I’rincipler nil11 I’rurtice of ‘I’cxtiltb f’I’illtillg, p. 481 et ~ a q .