Changes the ph of the fibre reactive dye and cellulose fibre so that the dye reacts with the fibre and makes a permanent connection chemically pure and of constant strength so more effective than washing soda 500gmixing instructionspastel shades 2g dye 50g salt 10g fixer then dye for 30 minutesmedium shades 4g dye 50g salt 15g fixer then dye for 60 minutesdeep shades 6g dye 50g salt 20g fixer then dye for 60 minutesfurther instructions are supplied with the product