There is the discharge printing method on dyed cloth (dyestuff is fixed) and the resist printing method in which a paste with alkali is over-printed after pad-drying the ground color (dyestuff is not fixed). Both methods are based on an idea of printing on dry cloth.

Table 5 Characteristics of finishing method

Finishing methods	Whiteness	Sharpness	Ground color leveling property	Finishing	Remarks
Ground dyeing				Large lot	Applicable for designs with a large ground color
Ground color padding				Large lot	Applicable for designs with a large ground and discharge print style
Pre-cover printing				Small lot	Applicable for resist print style
After-cover printing				Small lot	Applicable for resist print style

In addition, resist printing paste can be printed before the ground color is printed with the Wet on Wet or Wet on Dry method: the after-cover printing method, or resist printing paste can be printed with the Wet on Wet or Wet on Dry method after the ground color is printed: the pre-cover printing method. Table 5 shows the advantages and disadvantages of each method: For mass production with a large ground color design, discharge printing on ground dyeing or the ground-color pre-pad method are often considered, and the pre-pad method is outstanding because its great white dischargeability allows us to choose dyestuff in wide variety. Since with the pad method, any potential defect of the cloth becomes distinguishable, it is recommended to use a high performance padder (Roller Jet padder etc) in order to carry out even padding with ground color. In addition, if the hand of dried pad cloth is rough, it will be difficult to place cloth on the printing table, therefore, it will be necessary to choose an anti-migration paste which is often used in pad-bath, and sometimes using suitable dyestuffs or adding an auxiliary may be helpful. It is also important to know that the foam (the foam of dye solution or penetrating agent) which has been developed during padding can lead to uneven dyeing.
In the cover printing method which is suitable for small lots, especially the after-cover printing method, since the bleeding of pattern outlines can easily occur, paste compound (a compounded mineral thickening agent) with physical resist-printing effect is recommended. In the pre-cover printing method, the paste layer prevents bleeding, but the whiteness of discharge printing will decrease. Base color printing: rotary screen and gravure roll printing machines are appropriate for cover printing since the paste layer can be made comparatively thin by the devices.
In order to have fair color development, since with HPS (high-pressure steaming process), bleeding can easily occur, and the dry heat method will lead to a problem with discharge effect, the hand of cloth and color development, commonly HTS (high-temperature steaming process) is carried out.

[Preparing ground color pad-bath]
Sodium alginate, guar gum, CMC, synthetic thickener etc (Mignon NS: Senka Corporation--maleic acid copolymer) are used as anti-migration agents. It is widely accepted that sodium alginate with low viscosity is used since it has great anti-migration effect, however, ammonium salts of tartaric acid, citric acid etc are appropriate as pH buffer for the stabilization of dyestuff inasmuch as organic acid, such as maleic acid, tartaric acid etc, can easily lead to gelation.
In order to reduce the bleeding at pattern outlines, which can be a disadvantage of the pre-pad method, it is more effective to add organic acid. In addition, it is possible to prevent halation which is caused by alkali during steaming as long as the solid content of thickener in the pad bath increases as little as possible so as not to affect the hand of dried cloth.
For a pad bath, it is effective to add a degassing penetrating agent (with less foaming) or auxiliary (Senka Emulsyn) that softens the dried film if necessary.

<Pad-bath preparation>

x g		Disperse dyestuff for ground color
y g		Water
20 - 30 g		Anti-migration trickener
5 g		pH buffer
0 - 5 g		Penetrating agent (Succinol CSK : Senka CO.,LTD.)
0 - 30 g		Senka Emulsyn 300
1,000 cc

[Preparing cover-printing paste]
Considering leveling ground color and paste compound that is appropriate for HTS (de-paste property, color development), combining sodium alginate with modified starch, mid-etherificated CMC is recommended. Moreover, mixing O/W emulsion is appropriate to have stable levelness of print and color development.

<Examples of cover-printing paste preparation>

x g		Disperse dyestuff for ground color
200 g		Hot Water
500 g		* Stock paste
2 g		pH buffer (Organic acid)
10 g		Reduction inhibitor : Resister Liquid
10 g		Printing operation improver : Senkanol CN (Senka)
20 g		High color depth auxiliary for HTS : GTP-31 (Senka)
y g		Balancing
1,000 cc

<Stock-paste>

300 g		Sodium alginate with low viscosity (7%)
200 g		Modified starch(15%)
20 g		PRIMOGUM F-30 : Thickening type O/W emulsion paste
x g		Water
1,000 cc

[Preparing discharge-resist - printing paste]
The appropriate amount of alkali agent and solubilizer used varies depending on types of dyestuff and the dyestuff concentration, and it is also important to proceed with as small an amount as possible since too much use can cause outline bleeding and low concentration of effect color dyestuff. Sodium carbonate alone 100 g/kg and potash alone 70 g/kg are suggested as the highest limit, and the mixture of sodium carbonate/potash (1/1) should range between 50-100 g/kg while 100-150 g/kg solubilizer is added.
For thickener, etherificated starch, which has physical resisting effect, CMC with low viscosity, mineral thickener etc can be mixed. In the case of poor whiteness of the white-discharged area, i.e. becoming yellow, 20-50 g/Rongalit C is recommended.

<Examples of discharge-resist - printing paste>

White resist		Colored resist
50 - 100 g		50 - 100 g		Sodium carbonate/Potash(1:1)
100 - 150 g		100 - 120 g		Solubilizer
0 - 50 g		-		Rongalit C
500 g		500 g		Thickener
10 g		-		Fluorescent dye
-		x g		Disperse dye for effect color
-		20 g		High color depth auxiliary for HTS (GTP-31 : Senka)
x g		y g		Water or Thickener
1,000 g		1,000 g

It is recommended to use sodium alginate with good fluidity and paste removal properties or CMC with high etherification, in the base of modified starch and mineral thickener, which has good white-discharge effect and sharpness. However, it is necessary to be careful in using mineral thickener since it often leads to poor penetration of rotary screen and high mesh screen.

<Examples of discharge-resist thickener mixing>

(A)		(B)
200 g		300 g		Etherificated starch(15%)
500 g		-		Highly etherificated CMC (12%)
-		400 g		Low etherificated CMC (15%)
300 g		-		Mineral thickener (20%) : ECN-33(Senka)
-		300 g		Sodium alginate with low viscosity(7%)
1,000 g		1,000 g

[Finishing process : After dischargeresist printing]

[Finishing process : After-cover printing]