What is the cause of color stains?

Condensation of dyes. Due to the direct collision of dye molecules, they aggregate into larger dye aggregates (or dye associations). These larger dye aggregates are deposited on the fabric during the dyeing process, causing color stains. When dyeing:

(1) The free dye molecules will recrystallize during the heating (or cooling) process to form new crystal grains;

(2) The free dye molecules will gradually adsorb on the surface of the original dye crystals during the heating (or cooling) process, so that the original dye crystals will change from small to large;

(3) The dye particles in the free and semi-free state will directly collide and aggregate into larger dye aggregates without being dissolved. These larger dye aggregates are one of the important factors that cause color stains.