Warp Dyeing With Indigo Dyes

8/19/2019 Warp Dyeing With Indigo Dyes

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Indigo Dyeing – Various Methods Explained

And Compared

AdnanDecember 18, 20095

The indigo dyeing and processing methods -currently used – or dyeing indigo !arps !ere

introduced rom 19"8- 198" to obtain a higher producti#ity and sa#ings in dyeing or to achie#e

the re$uired dar%er shades &hard roc% !ashing, super blue, sot denim', or sotness o the yarnor inal inishing( The ollo!ing table gi#es you a comparison o the possible processing stages

such as)

1- *ndigo rope dyeing process

2- *ndigo one sheet dye slashing

+- *ndigo double sheet dyeing

- oop dye 1 or . &continuous dye slashing'

5- oop dye 1 or . !ith dyemer &continuous merceri/ation dyeing and si/ing'(

or the i#e maor *ndigo dyeing methods or the basic denim, super blue denim, sot denim,

stone !ash denim, !e also must ta%e into consideration that a certain appearance o the garments

is only achie#ed ater a certain !ashing method( &hemical !ashing, stone !ashing, hard roc%

!ashing', use o certain si/ing agents &sot denim' or irregular appearance in !arp or !etdirection by using a yarn !ith slubs and neps &antic denim'(

The inal inishing methods ha#e inluence on abric construction and dyeing methods(

CHEMICAL WASHED DENIM

The creator o sno! !ash denim or o -side denim is Edin Co! Limited "apan! Thesechemical !ashed types o ready made garments sho! less tensile strength and a harder hand(

S#$NE WASHIN%

3ith sot stones it ta%es 20 – +0 min( to achie#e the desire surace appearance(

D&' (LEACH

4ot roc% are soc%ed !ith chloride and the garment treated in !ashing machines(

HA&D S#$NE WASHIN%

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Treatment ta%es appro( + – hours( A #ery sot hand the garments is achie#ed( Due to the

etended time o treatment in !ashing !ith hard roc%s the strength o abric is inluenced( This

treatment re$uires impro#ed yarn $uality and deeper dyed shades( 6ard stone !ashing ades out partly at hems and stitched lines(

S)*E& (L)E

Deepness shade is achie#ed by dyeing in 8 – 12 dye boes !ith rope dyeing methods( 3ith

merceri/ed yarn !here the colour stays at the surace o the yarn &ring dyeing' !ith continuousloop dye range !ith integrated merceri/ing and dyeing unit &dyemer'(

(LAC+ DENIM

4ulur dyed, pada/oic dyed etc( on continuous dyeing si/ing machines or loop dye ranges(

INDI%$ D'ES#),, AND I#S CHA&A#E&IS#ICS

*ndigo has despite many other blue dyestus %ept its popularity( This by no doubt is achie#ed bythe act that *ndigo has a number o properties !hich ha#e in this combination not yet been

achie#ed by other single dyestus(

The main properties are)

• 7leasant colour shade(

• 7ossibility to achie#e by simple repeated dipping, deep marine blue shade(

• 7ossibility to dye cotton in cold dye bath(

• ompetiti#e in price(

• 7ossibility to achie#e an acceptable colour astness and the eceptional ad#antage by

repeated !ashing o ading colour, to %eep the colour shade that al!ays a clear, pleasant blue shade result(

The ollo!ing dra!ing sho!s the symbolic built-up o dye stu o the yarn according to the

multi-deep process(


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The s%etch sho!s ho! *ndigo layers one ater the other are

placed on the surace o the yarn then again scraped o, similar to %nie through orce or tensionor by !ashing(

An *ndigo has only a #ery lo! ainity and the depth o colour o the ibre is achie#ed by

repeated dipping oidation( ach dipping cycle occur in a certain balanced manner as dye stu

is obser#ed by the ibre at the same time and part o the already oidi/ed dye stu is reduced andmigrates rom the ibres(

3ith increasing dipping operations , the balance o absorption migration mo#es to!ards

migration(

A #ery important actor or the reduction o migration is the s$uee/ing eect and the oidation

!hich ollo!s( A high s$uee/ing eect promotes a $uic% and thorough oidation and reduces themigration and reduction in the ollo!ing bye bath(

3ith the lo! s$uee/ing eect ie !ith high li$uid absorption, the purely #isual impression o a

good oidation can be decepti#e as the outer colour s%in loo%s blue( *n the core o the thread

ho!e#er less #at dye stu may be deposited

et us ha#e a close loo% at the dierent dyeing systems(

C$NVEN#I$NAL CLASSICAL C$N#IN)$)S INDI%$

&$*E D'EIN%


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The classical rope dyeing system is #ery labor intensi#e and consists o)

• :all !arping

• *ndigo dyeing

• ;ebeaming on long- chain-beamer

• 4i/ing


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6a#ing passed the dyeing and oidation rage the ropes are guided through 2 or + !ashing boesto !ash o ecessi#e dye (*n the last bo sotener are added to ease the opening o the ropes(

They are dried in a series o cans( The dried ropes !hich contain +80 – 20 ends are then

deposited into large coilers (;ebeaming !ith +00 – +80 ends per rope is easier( These coilers are

placed behind the long chain beamer !here the ;ebeaming and opening o the ropes ta%es place(*n order to guarantee e#en yarn tension through ;ebeaming on to a bac% beam ready or si/ing

the ropes are guided o#er a tension de#ice !hich is placed appro( 10 -11 meters distance rom

the long chain beamer( :ro%en ends !hich #ery really happen during process o the rope dyeingare repaired at this process stage( *nitially these machines !ere supplied !ithout yarn stop

motion but are a#ailable no! a days on special re$uest( This is o maor importance as lost ends,

lu, + – tail ends and yarn remnants can cause inerior perormance in !ea#ing(

The so prepared bec% beams are no! si/ed in a si/ing machine preerably !ith 2 si/e boes( Thesi/e pic% up #aries bet!een 8 – 10@( *n urope mainly modiied starches !ith binders are used,

!hilst in ?4A certain lo! @ o 7A is applied in combination !ith starches by some companies(

Depending on the inal inishing process &!ashed denim' !ith no iller also B gi#es ecellent perormance in !ea#ing( 4pecial si/e mies or sot denim !ill be discussed separately( 3e

recommend ho!e#er not to use 7A or si/ing o denim as a surace o denim may sho! a

leather s%inned appearance(

C$N#IN)$)S SLASHE& D'EIN% S'S#EM

ontrary to the *ndigo rope dyeing system, or the continuous slasher dyeing and si/ing bac% beams are used( That means that the total >o o ends re$uired or a !ea#ers beam are dyed,

dried, si/ed and dried simultaneously( The bac% beam contains similar to rope +80 – 20 ends butdistributed e#enly o#er the !idth o 10 or 1.0 cm bet!een the langes so the end lay parallel to

each other, !arp length 12 – 15(000 meters, similar to the rope dyeing system the ull >o o ends

are pretreated &!ashed' dyed in dye boes and oidi/ed, no sotener are used in the last !ash

bo(


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C$N#IN)$)S INDI%$ D'EIN% AND SI-IN% *&$CESS

3e must ho!e#er consider that the s$uee/ing eect is lo!er and thereore the danger o

strea%iness and shade #ariation rom centre to out side is also higher( onse$uently it !ould be

better to reduce the !arping !idth rather to 10 cm instead o using !arper beams !ith 1.0 –180 cm !arping !idth(

The immersion time in the dye boes is appro( 10 – 15 seconds and time or oidation +0 – .0

second( The inal result is a !ea#erCs beam( This system allo!s the installation o less epensi#e

dye rage and less additional preparatory machinery(

=ne o the disad#antages pre#iously !hen !arp preparation &%nots, !ea%, thic% places' !as not%ept at a #ery high le#el !as that ends so!n in the dyeing range could cause maor color

#ariation through machine stops(

D$)(LE SHEE# C$N#IN)$)S D'EIN%

7atents applied or double shade dyeing by E! %odau date bac% as 19".( 3ith the system dyeingsi/ing is done in 2 operations( The main reason or dyeing o 2 sheet simultaneously is achie#ed

a more e#en dyed sheet, that means 8000 – 8200 end are dyed, oidi/ed, dried and the ull length

o the !arper beam 12(000 – 15(000 meters lange diameter( These beams are transported !iththe aid o air cushions to the si/ing machine and the yarn sheet si/ed in double si/e boes(

*mmersion time and oidation time is the same as !ith continuous slasher dyeing(

Indigo .ull/idth arping pro0ess


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3ith double sheet dyeing the linear !arp thread density is doubled( Thereore)

• 4$uee/ing eect is increased,

• An e#en s$uee/ing o#er the !hole !idth is achie#ed,

• ondensation and concentration o ends at one spot sho! compared to single sheet

dyeing no colour strips ormation, strea%iness or shading in the inished abric(

• The production out put o the dyeing is increased by "5@(

• Dyeing o + layers o yarn simultaneously is possible but #ery diicult to control the

beaming on + big !arp batches(

?nortunately the double sheet dyeing machine as !ell as the rope dyeing range cannot be lin%ed

!ith a si/ing machine !hich must be regarded as disad#antage as the processes o dyeing and

si/ing must be carried out separately(

Loop dye system 1 .or 2

4imilar to the sheet dyeing systems 10 – 1. !arper beams !ith the total number o ends re$uired

or the !ea#er beams are used( The !arper beams are placed in a mo#eable !arp creel !hich can

be loaded !hilst one set is in potation(


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The yarn sheet is guided to the soa%ing bath through a eed-in system !ith tension compensationrollers( The soa%ing bath has the tas% to prepare the yarn or the ollo!ing dyeing operation(

The yarn sheet ater ha#ing been immersed into a single indigo dye bath runs into a long loop

!here oidation ta%es place( As you can see rom the slide the bac% beams are inside the yarn

sheet passes through the dye bo as oten as necessary to obtain the re$uired deepness o shade(

=ne o the ad#antages is)

*deal, utili/ation o 6ydrosulphite through s$uee/ing – . layers simultaneously and oidation

o yarn in a comparati#ely long oidation loop( Ater the oidation the yarn sheet is guided

through 2 !ashing boes into a yarn accumulator and inally on to a series o drying cans, driedup to 25 – +0@ inal moisture content prior being immersed into si/e boes, dried and !ound

onto a !ea#ers beam(

The molecules are controlled D dri#e to maintain !arp tensions( Temperatures are

automatically controlled as !ell as the 76 #alue in the dye bo( The automatic control unit o the76 #alue supplies automatically hydrosulite and caustic soda to stabili/e the present #alue rom

the start to end o a dye set(

All rollers arein contact !ith the dyed sheet are luted, they %eep the sheet in position and

reduce deposit o dye and build-up o other deposit &lu'( *n addition to !idth is controlled by

guides to ensure e#en distribution o the yarn layer o#er the !hole !idth o the dyed sheet(

All accumulators placed bet!een !ashing boes and drying cans guarantees a continuous

production o the dye range !hen a !ea#er beam has to be echanged at the head stoc%(

The creels can be loaded !ith bac% beam !ith 1200 mm diameter !hich allo!s to !arp appro(+.(800 meters o yarn, count >o ", 5 &te "8' or 50(000 m count >o 10 &te .0'( This means that

depending on the count normally one cyl-spool is used in !arping to ill a !arper beam(


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WA&*IN% S*EED

*&$D)C#I$N

4peed #aries bet!een 1000 mmin, +5 mmin( >o 5, 5 &te 10"' and 2 mmin( >o 10 &te .0'

MACHINE S#$*S D)&IN% SI-IN%

or +.800 m, recorded on epansion comb(

WAS#E $, MA#E&IAL

Appro( 15-20 %g per set(

#IME &E3)I&ED ,$& CHAN%E $, SE#

2 hour

Linear arp densities in the s4uee5e!

The linear density in the nip is calculated in the same manner as or si/ing(

E linear thread density

E ends in cm -1

DE diameter o yarn

DE 0,921 mm E 0,921 E 0, 29125

>m 10 E +(1.22

E D

As already mentioned pre#iously the !arp density has an inluence on colour astness( A higher

s$uee/ing eect is achie#ed due to the o#er laying o the !atp ends this also gi#es more side toside s$uee/ing, thereore reduce strips ormation( The high s$uee/ing eect results also in better,

$uic%er and proper oidation and better colour astness(

*t must be mentioned that recommended dip and oidation times on !arp dyeing ranges are o

little use i not the s$uee/ing eect is ta%en into consideration( ?nder a gi#en s$uee/e pressure,or instance 500 %g the s$uee/ing eect o the mentioned - dyeing systems can be compared(

3e can see that similar s$uee/ing eect can be achie#ed !ith the loop dyeing system 1 or .

&"5@' as !ith rope dyeing "0 – 110@( Double dyeing !ith 2 layers !idth !ith 150 cm gi#es


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appro( 80@ s$uee/ing eect, !hilst single sheet slasher dyeing #aries depending on count

bet!een 100 – 1+0@(

Loop dye 1 .or 2 &ope/dyeing Slasher/dyeing

As only one short indigo dye bath is deeded only one eeding tan%s, no separate eeding ochemicals is necessary(

Dye li$uor is use in 1500 1 instead o .-500 1, thereore less chemicals are in use at same time(

• o!e po!er consumption(

• ine counts can be dyed as !ell &>o +0'

• or dar% shades, blac% shades or other shades needed by ashion, other indanthrene dye

stu can be directly added into the indigo dye bath &indanthrene yello! or orange'(

L$$* D'E 1 ,$& 2 C$M(INED WI#H D'EME&

The demand or dar% shades specially dar% marine blue or super blue denims also led to ne!

ideas in indigo dyeing ranges ha#e been increased bet!een 8-15 dye boes !ith corresponding

oidation ranges(

*n some cases 6ydroyaceton has been specially treated !ith high re$uency( :esides achie#inga dar%er shaded !ith the desire greenish touch it is #ery suitable or biological treatment(

*n order to achie#e ring dyeing, merceri/ed yarn has also been used( Berceri/ing pre#ents penetration o dye stu into the inner code it is suitable or this purpose to obtain an optical blue

eect and superior colour astness and beha#ior in !ashing( Berceri/ing is #ery costly, thereore

ne! !ays in continuous merceri/ing and indigo dyeing !as ound(


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D'EME&

The dyemer range is integrated(

or impregnation padder or hot caustic solution is placed ater the heating system( The yarn is

guided o#er cold cylinders and !ith an adustable roller the tension o the yarn sheet can beadusted according to the re$uired tension prior to the scouring in 2 more boes(

Ater ha#ing passed this, the yarn sheet is immersed into the dye bo and the same process as!ith the loop dye method is repeated(

C$N#IN)$)S D'EIN% AND SI-IN% $N #HE D'EME& &AN%E

* ashion needs other colours than indigo blue it is comparati#ely simply to dye and si/e on this

range(

Slasher Dyeing Vs &ope Dyeing – A 0omparison

Comparison $n Slasher Dyeing &ope Dyeing

;e$uired 4pace ess Bore

Berceri/ing asy Diicult

Banpo!er ess Bore

Dye bath ess capacity Bore

e 1-+0

!ithout maorchange

an use >e1-1.

!ithout maorchange

leibility leibility to

produce denim in

dierent colors and

ess leible(

Diicult to change

colors(


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small $uantities

ost ost o production

is lesser compared

to ;ope Dyeing

ost o production

is more compared

to ;ope Dyeing

A6out the author7 Adnan is a tetile engineer and !or%ing !ith a reputed denim mill in7a%istan(6e is loo%ing ater ne! denim de#elopments(

Warp Dyeing With Indigo Dyes

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