Dyes (as opposed to pigments) have small particle size and lend their colour to products by solubising. The benefits of dyes is that they maintain complete transparency which is ideal in clear liquid bases or in melt and pour soaps. Some dyes are less tollerent of extreme pH environments than others which means not all are suitable for use in alkali products such as CP soaps or in acid environments such as in bath bombs where citric acid is used.
When further dilute in water, dyes often appear a different colour from that of their concentrated liquid or powdered forms. Dyes should always be used sparingly and never added to any dry toiletries in their powdered form.
Dyes will 'bleed' in melt and pour soaps. Many of our powdered dyes are now being manufactured in fine granular form which helps reduce airborn dust when handling.