vat dyes

Vat dyes are an ancient class of dyes, based on the natural dye, indigo, which is now produced synthetically. Vat dyeing is a process that refers to dyeing that takes place in a bucket or vat. Almost any dye, including fiber-reactive dyes, direct dyes, and acid dyes, can be used in a vat dye. Cotton, wool, and other fibers can be all dyed with vat dyes. Although almost all dyeing can be done in a vat, the term vat dye is used to describe a chemical class of dyes that are applied to cellulosic fiber (i.e. cotton) using a redox reaction as described below. Because of the use of caustic soda, and the very high pH of the dye bath in the dyeing process, wool cannot be dyed using vat dyestuffs. Wool is soluble in caustic soda solutions.

Vat dyes are essentially insoluble in water and incapable of dyeing fibers directly. However, reduction in alkaline liquor produces the water soluble alkali metal salt of the dye, which, in this leuco form, has an affinity for the textile fiber. Subsequent oxidation reforms the original insoluble dye. The color of denim is due to indigo, the original vat dye.

Vat dye is obtained through oxidation. It is usually very bright and will hold up better when bleached than most other dyes. The process is very colorfast in all respects. This is an expensive procedure and is used mainly on high-end products. Vat dyes include the natural dyestuff, indigo, and the artificial dyes called by the trade names, indanthrene, and flavanthrene. They are called vat dyes because, being originally insoluble in water, they undergo special preparation in large vats before the cloth is introduced; here they are made soluble, usually by the adding of caustic soda and hyposulphite. In this mixture or dye liquor the textiles are soaked. Certain chemicals are thereafter added, changing the dyestuff back to the insoluble form in the cloth or fiber. This is called the fixing process. All the vat dyes are fast, especially to washing. The artificial vat dyes have in many instances taken the places of the older mordant dyes, and their future seems promising, for they are cheaper and easier to apply than the mordants, although not so cheap and convenient as the direct dyes.

VAT DAYS

VAT DYES
SHADES PRODUCT NAME C.I. No. CAS NO.
Yellow 5G (Acra) Powder Yellow 5G M/D YELLOW 2 129-09-9
Golden Yellow GK Powder Golden Yellow GK M/D YELLOW 4 128-09-9
Yellow RK Powder Yellow RK M/D ORANGE 1 1324-11-4
Yellow 3RT Powder Yellow 3RT M/D ORANGE 11 2172-33-0
Gold Orange 3G Powder Gold Orange 3G M/D ORANGE 15 2379-78-4
Pink R Powder Pink R M/D RED 1 2379-74-0
Red 6B Powder Red 6B M/D RED 13 4203-77-4
Purple 2R (Acra) Powder Purple 2R M/D VIOLET 1 1324-57-8
Magenta B Powder Magenta B M/D VIOLET 3 2379-75-1
Blue RSN Powder Blue RSN M/D BLUE 4 81-77-6
Blue 2B Powder Blue 2B M/D BLUE 5 16413-80-9
Blue BC Powder Blue BC M/D BLUE 6 130-20-1
Navy Blue BR Powder Navy Blue BR M/D BLUE 18 1324-54-5
Dark Blue BO Powder Dark Blue BO M/D BLUE 20 116-71-2
Blue 4G Powder Blue 4G M/D BLUE 29 1328-50-3
Green FFB Powder Green FFB M/D GREEN 1 128-58-5
Green 2G Powder Green 2G M/D GREEN 2 25704-81-8
Olive Green B Powder Olive Green B M/D GREEN 3 3271-76-9
Black BB Powder Black BB M/D GREEN 9 6369-65-9
Brown BR (Acra) Powder Brown BR M/D BROWN 1 2475-33-4
Brown R Powder Brown R M/D BROWN 3 131-92-0
Brown RRD Powder Brown RRD M/D BROWN 5 3989-75-1
Black BB Powder Black BB M/D BLACK 9 1328-25-2
Grey 2B (Acra) Powder Grey 2B M/D BLACK 16 1328-19-4
Olive T Powder Olive T M/D BLACK 25 4395-53-3
Olive D Powder Olive D M/D BLACK 27 379-81-9
Black AC Powder Black AC M/D BLACK 34 12271-03-3
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SOLUBILISED VAT DYES

SOLUBILISED VAT DYES
SHADES PRODUCT NAME C.I. No. CAS NO.
Jaffsol Gol. Yellow IGK YELLOW 4 3564-70-3
Jaffsol Gol. Yellow IRK ORANGE 1 1324-15-8
Jaffsol Red Violet RF VIOLET 3 2379-75-1
Jaffsol Green IR GREEN 1 2538-84-3
Jaffsol Bril. Violet 14R VIOLET 1 1324-57-8
Jaffsol Blue 04B BLUE 5 2705-33-2
Jaffsol Brown IBR BROWN 1 23725-15-7
Jaffsol Brown IRRD BROWN 5 4425-36-9
Jaffsol Grey IBL BLACK 1 3687-67-0