Normally, cotton fabric is dyed by reactive dye, the color absorption penetrate through the fiber and have good color fastness, therefore, we seldom find color bleeding during wash cotton T shirts, Polo shirt etc. However, color absorption may saturate in dark, deep navy colors, which sometimes exhibit color bleeding / staining if post-treatment in color fastness is not well conducted. On the other hand, polyester fabric are usually proceeded by disperse dye under high temperature. Customers have to understand that due to the repeat use and wash, the fiber itself will deteriorate and the color will also run vintage, result in a fading visual effect.