Needle Necessities floss is a fine Egyptian cotton that has been overdyed by hand to create subtle shading. It is often vari-coloured but two-thirds of the 171 colours are primarily within a colour family. Upon opening your skein you will notice the colouring is unevenly "bled" from one shade/colour to the next. This is done to give you a smooth transition of colour in your stitching, especially for shading.