Dissolving methods of seven commonly used dyes

1. Direct dyes:

Direct dyes have relatively good heat resistance and stability. Direct dyes can be dissolved in soda ash and soft water. When dissolving, we first use cold soft water to make the dye into a slurry, then boil the soft water to stir and dissolve, and dilute with heated water. After cooling, add water to the specified liquid volume.

2. Reactive dyes:

This type of dye is not heat-resistant and is easily hydrolyzed at high temperatures. It is advisable to use cold soft water to make a slurry, then use soft water of a suitable temperature to dissolve the dye according to the hydrolysis stability of different dyes, heat the soft water to dilute, and after cooling, add soft water to the specified liquid volume.

Low temperature type (X type): use cold water or 30-35℃ warm water (has been basically eliminated)

High temperature type (K type, HE type, etc.): use 70-80℃ hot water

Medium temperature type (KN, M type): use 60-70℃ hot water

Low solubility: use 90 ℃ hot water

3. Vat dyes:

The dissolution process of vat dye is a reduction reaction process. When dissolving, the dissolution temperature must be determined according to the reducing conditions of the reducing agent used. For example, the commonly used reducing agent for vat dyes is insurance powder. The optimal use temperature in the solution is 60°C. Excessive temperature will cause a large amount of insurance powder to decompose.

(1) Whole bath method:

Put the dye into the dyeing cup, add red oil and a small amount of warm soft water and mix thoroughly. Then add the prescribed amount of caustic soda and insurance powder, add soft water to the required bath volume, and restore at 55°C.

(2) Dry cylinder method:

Put the dye into the dyeing cup, add red oil and a small amount of warm soft water and mix thoroughly. Then add two-thirds of the amount of caustic soda and insurance powder, so that the amount of dye solution is one-third of the total amount. The dissolution temperature should be determined according to the reducing conditions of the reducing agent used. Add the remaining caustic soda and insurance powder to the dye cup, and add soft water to the required bath volume.

4. Sulfur dyes:

Accurately weigh the required amount of dye into a beaker, mix it into a slurry with cold soft water, then add the pre-dissolved sodium sulfide dye solution and boil for 10 minutes. Heat the soft water and dilute it. After cooling, add the soft water to the specified liquid volume.

5. Disperse dyes:

If the temperature is too high, disperse dyes tend to crystallize and precipitate. When dissolving, it is advisable to use cold soft water to mix the slurry first, then use cold soft hydration material below 40℃, and add soft water to the specified liquid volume.

6. Acid dyes:

Acid dyes have relatively good heat resistance and stability. When dissolving acidic dyes, first use cold soft water to make the dye into a slurry, then boil the soft water and stir to dissolve, heat the soft water to dilute, and after cooling, add soft water to the specified liquid volume.

7. Cationic dyes:

Cationic dyes have relatively good heat resistance and stability. When dissolving, first use concentrated acetic acid (solvent) to make the dye into a slurry, then boil soft water and stir to dissolve, dilute with heated water, and after cooling, add soft water to the specified liquid volume.