When the ultimate in wash and boil fastness is required.
Also used to dye over fibre reactive dyes (Drimarene-K) for multi layered dyeing.
Vat dyes are insuluble in water, and to be able to be applied to the cloth must be first "reduced" to leuko form with the aid of Caustic Soda and Sodium Hydrosulphite. To complete the dyeing, vat dyes have to be converted back to their insouluble form. This is done by simply hanging them "oxidise" in the air. Vat dyes have extremely high wash and boil fastness.
Important practical propery is that they can be appied over material dyed with fibre reactive dyes, partly or completely stripping them thus creating multiple layered dyeing. Very effective for Shibori technique over fibre reactive (Drimarene-K ) dyes.
270g Caustic Soda (Lye)
1 litre cold water
15 litre hot water
17g Vat Dye
62g Sodium Hydrosulphte (Hydros)
Sprinkle 270g Caustic Soda over 1 litre of cold water and leave to dissolve. Bottle and safety label - this solution is corrosive. This solution is called "loog"
1. Paste 17g dye in little hot water then add 80ml hot water at 60C° , add 17 g Sodium Hydrosulphite an leave it to "vat" for 15 minutes.
2. Meanwhile make another vat consisting of;
14.2 litre of water with temperature anything between 30 - 60C°
45g Sodium Hydrosulphite
Now add the dye mixture from the first vat to the second vat. Immerse material and dye for 10-20 minutes, depending on depth of shade required.
Rinse in cold water and hang out to oxidise.