i)

Exhaust dyeing method (Jigger Machines)

Set the dye-bath with required amount of water at 40^oC and add half the amount of dyestuff solution with 1-2 g/l resist salt, run for 1 turn and add the remaining half amount of dyestuff solution and run for another turn.

Then add half of the salt and start raising the temperature slowly. (such that 65 to 85^oC temperature could be attained after two turns). Run for I turn and then add the remaining amount of the salt and give it another turn.

Now add half the amount of predissolved alkali and give one turn. Temperature is maintained at 80^oC. Add remaining half amount of alkali and give another three turn for better fixation give two more turns and then drain the jigger.
 

ii)

Exhaust dyeing method (Winch Machines) Viscose Rayon

The dye bath is set at 50^oC with 20 parts/1000 parts resist salt and dissolved dye solution is added and fabric is dyes for 10 minutes.

The required amount of salt is added and goods are dyed for about 15 minutes. Then soda ash is added and dyeing is continued for further 10 minutes. The goods are then washed.

Salt and alkali requirements - Parts/1000 parts

 

iii)

Pad-dyeing method

`H' dyes are applicable by this method by using padding mangle and suitable drying and steaming equipments as per requirement.

(a)Pad - Dry - Bake - Wash

 

The fabric is padded cold in above padding liquor and dried in hot flue, hot air stenter or in drying cylinders. The dried fabric is then baked for 30 seconds to 5 minutes at 200-160^oC for fixation. The drying before thermofixation should be slow and even to avoid migration and an unlevel condition.

(b) Pad - Dry - Steam - Wash

 

The fabric is padded cold in above padding liquor and dried in hot flue. The fabric is then steamed for 3-10 minutes at 100-150^oC and washed-off.

(c) Pad - Dry - Chemical pad - Dry - Steam - Wash

The dye is dissolved with a minimum amount of urea and 10 parts of resist salt per 1000 parts and liquor. The fabric is then padded cold, dried and passed through caustic soda in brine solution and then steamed for 60-75 seconds at 100-105^oC and washed off.

Parts/1000 parts

(d) Pad - Batch - Wash - Dry

The fabric is padded in the above padding liquor and covered with a plastic sheet. Keep it for maximum 24 hours and wash.

Washing off procedure

In order to obtain maximum wet-fastness properties, brightness and purity of shades with consistent dyeing results. It is essential to give a through 'Soaping' to clear off unreached hydrolyzed dye from the dyed fabric.

The dyed fabric is rinsed repeatedly in cold water to remove of the alkali, salt and unfixed dye present and rinsed again in warm water not higher than 60^oC then run in a bath containing:

Anionic detergent - 1/2 gms/liter for 15 minutes at the boil. Then rinse in warm water (up to 60 ^oC) and finally in cold water. The most satisfactory results in Washing off, particularly for piece goods are obtained by employing an open soaper or perforated Beam-washing machine. If such equipments are not available, conventional ones like jig or winch may be used. For yarn in the hank form open-vat is employed and for yarn in packaged form the package-dyeing machine itself used.

(B) Printing Methods

Due to low reactivity of these dyes the print paste stability containing alkali is very good. Secondly due to low substantivity the hydrolyzed dyes have the least tendency to stain adjacent white materials and thus these dyes are more popular for use by printing applications, the different printing methods are as under:

(i) Print - Dry - Steam - Wash - Dry
('H' dye with alkali) Printing recipe

Process

Mix dye powder with urea and pour hot water of temperature about 80-85^oC and stir well to dissolve completely. Add this dye solution to sodium alginate thickening paste containing resist salt stir well to mix. Just before printing add sodium bicarbonate.

Print the cloth with above print paste and dry. Avoid over-drying and protect printed goods from acid or reducing fumes. Then steam dried goods for 5-8 minutes on rapid ager or 15-20 minutes on star ager.

(ii) Print - Dry - Bake - Wash - Dry
('H' dye with alkali)
 

Process

Prepare the print paste, print and dye the goods. The dried goods are then baked as under:
 

* use Sodium Bicarbonate for Blue H5G and Red Brown H4R. Use 30 parts soda ash with black HN.

(iii) Print - Dry - Pad - Batch - Sodium Silicate - Wash - Dry
(`H' dye without alkali)

The cloth is printed with the above paste and dried. The dried goods are then padded in a sodium silicate solution of 100^o Tw and padding goods are batched on plastic sheet and kept for about 15 hours and then washed. (Silicate : 1:2:1 Na₂O : SiO₂ ratio).