Kraftkolour’s Hydros ST (Sodium Hydrosulphite 25) is a professional-grade reducing agent used primarily in indigo and vat dye processes. Its primary role is to remove oxygen from the dye bath, converting insoluble vat dyes into their soluble “leuco” form so that they can penetrate fabric fibres evenly and permanently.

This 25% concentration formula is designed for both large-scale textile production and small artisanal dyeing studios, delivering reliable reduction strength without excessive waste. It dissolves quickly and works efficiently at lower temperatures, making it ideal for a wide range of dyeing conditions.

Hydros ST ensures smooth colour uptake and prevents patchiness by maintaining a stable reducing environment throughout the dye bath. When paired with an alkali like Soda Ash or Lime, it creates the perfect conditions for authentic indigo dyeing, yielding deep, long-lasting hues that retain their brilliance.

Benefits

• Industry-standard chemical trusted for precision dyeing.

• Fast-acting and consistent reduction performance.

• Provides even dye penetration and superior colour depth.

• Safe for use in controlled, ventilated environments.

• Compatible with Kraftkolour’s Natural Indigo and Synthetic Indigo ranges.
  
  

Ideal Applications:

• Natural or synthetic indigo vat dyeing.

• Discharge printing and bleaching processes.

• Maintaining vat health during extended dyeing sessions.

• Re-reducing oxidised indigo vats.