'Some ofthe vat printing process for overprint and brasso print method- A case study'



When ever overall fastness is required in dyeing and printing method for cotton area always vat dye is preferred first. In market it is available asa powder form and paste form also. Vat dye can be classified commercially fromits particle size powder form; acra com form and micro disperse form.


Now a days commercially vat paste is used in printing method .In vat printing we are going to discuss their printing process in rotary printing machine along with some popular shade like military khaki ,brasso print etc.


In Brasso paste high concentration of acid liberating isused to remove celluloses portion from polyester cotton blend fabric.


Rotary printing machine:-Here we are going to discuss vatoverprint process on vat dyed ground. For standard cutting see scanned photo ofkhaki print (figure: Case I).


Quality:-cotton drill

Construction:-warp*weft=14 *10 count.

Reed * pick=4/46*48

Grey width=155 cm

Weight/meter=460 gm/meter.

Process:-overprint on vat dyed khaki ground.

Order:-Government military khaki dress.

Machine used:-rotary printing machine.

Meter=20,000 meter.

Speed =18 meter/minute.

Colour screen used=2

Magnetic rod size used=20 mm.

Colour =Brown paste and olive green paste.

Repeat of screen=640 mm.

Screen mesh size=130 mesh per inch square.

Gum paste (Gum indalca):-

Safolite=8%

Soda ash=6%

Potash=2%

Gum (7%) =Rest% 100 kg


Olive green solution:-

Vat olive green FFB (Paste) =52 kg.

Hot water=52 kg.

Glycerin=52 kg.

Gum paste=balance.

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Total=1800 kg (For 20,000 meter fabric)


Brown solution:-

Vat brown RRD (paste) =130 kg.

Gum paste=balance

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Total=1400 kg (for 20,000 meter fabric)


Process: Print drysteaming at 105-110 degree Celsius holding time 15 minutes---washingin open width washing machine---drying and finishing.


 

Case study number- II (Rotary Printing Machine)

For standard cutting (figure: Case II)

Quality=polyester cotton blend sari.

Grey width=124 cm.

Weight per meter=80 gram/meter.

Speed=8 meter/minute.

Brasso paste recipe:-

Sodium bisulphate:-30%

Glycerine:-5%

EL-40:-1%

Snid PGN=0.1%

Stock paste= rest% 100%



Stock paste recipe:-

Safolite=16%

Soda ash=12%

Potash=4%

Kanji (7%) =rest% 100%


Recipe



Conclusion:


This printing process is written because vat printing is nowadays less in demand due to cost factor but definitely for export quality this will be a better choice. In printing space is very less in every area accuracy is needed because once fabric is printed its correction will be very difficult.


Before going for bulk trail take lab trail first and for printing take only expert view only.


This article is written in good faith and problem solving altitude purpose.


About the Author:


The author is the Product Manager (Reactive Dyes) in Colourtex. Ind. Ltd having vast experience of 12 years in production of cotton, polyester and its blend quality in India and overseas reputed company.