Vat Blue 1 (Indigo blue) is blue powder. It is insoluble in water and alcohol; soluble in aniline solution (hot). It is yellow green in concentrated sulfuric acid, blue precipitate after dilution. Red yellow blush is formed in concentrated nitric acid. Heating to 170 ° C into a purple-red gas, sublimation phenomenon, but does not decompose; in the enclosure, dry distillation, decomposition into aniline. The leuco body formed by the dye in the alkaline powder solution is light yellow, in the acid insurance powder solution white.
Indigo blue,Vat Indigo,Indigo
Vat Blue 1 Mainly also be used for wool and silk carpets and handicrafts in the application. Pure product is used in food dyes, can also be processed into organic pigments.
Vat Blue 1 should be stored in a cool, dry, ventilated place, pay attention to fire and moisture.
Dyeing depth g/L | 30 |
Dyeing method | IN |
Leuco color | Blue |
Leveling property | ▲▲ |
Dead cotton | △ |
Light (Xenon test 1/12) | 6-7 |
Light (Xenon test 1/1) | 7-8 |
Light (Xenon test 2/1) | 7-8 |
Dyeing method | Dyeing temperatuer (℃) | Reduction method | Reduction temperature (℃) | Leveling Property | other Properties |
C | 20~25 | Dry Cylinder | 50~60 | medium | Very low affinity |
light fastness | soapping(95℃) | Perspiration | Rubbing | Ironing | Bleaching resistant | Merceized | |||||||
standard depth | 1/12 depth | orginal color changed | white fabric stained | orginal color changed | white fabric stained | Dry | Wet | immediatly | 4hafter | chlorine bleaching | Oxygen bleaching | orginal color changed | white fabric stained |
3~4 | — | 2 | 4 | — | — | 1~2 | 1 | — | 5 | 2 | — | 4~5 | — |
Vat Blue 1 is insoluble as supplied. In the dyehouse it is reduced under strongly alkaline conditions (commonly using sodium hydrosulphite + caustic soda or controlled electrochemical reduction) to produce the water-soluble leuco form. Fibres are dipped while the dye is in leuco form; exposure to air oxidizes the dye back to its insoluble blue state on the fibre, locking in excellent fastness.
Reduce crocking by adopting: (1) multiple lighter dips instead of one heavy dip, (2) an optimized oxidation step (gentle exposure rather than harsh aeration), (3) after-treatments such as resin crosslinking or silicone finishing to improve surface fixation, and (4) enzyme or polishing finishes that remove loosely bound particles. Lab test with Wyzenbeek or crockmeter before scale-up.
Vat Blue 1 performs best on cellulose fibres (cotton, viscose). It can be used on some protein fibres (wool, silk) and blended substrates but requires process optimization; on wool/silk, use milder alkaline conditions and lower temperatures to avoid fibre damage.
Because the dyeing process uses reducing agents and caustic, effluent contains residual reducing salts and high pH. Best practice: neutralize pH, remove excess reducing agent (air oxidation or chemical dosing), and use biological or advanced oxidation treatments for organic load. Recover and reuse washwaters and minimize sodium hydrosulphite overdosing to reduce sulfite discharge.