What you must do

You must strictly control your use of 'blue colourant' (EC number 405-665-4 in the European Inventory of Existing Commercial Chemical Substances) for colouring leather articles. You cannot use it as a substance or in preparations at concentrations higher than 0.1% by mass.

Good practice

Consider using liquid dyes instead of powder dyes. This will help you prevent dust.

Handle and dispose of dyes with care. Make sure you do not spill dyes as treatment plants may not remove them from the effluent. Even a very small amount of dye can discolour a watercourse and could affect downstream water users.