Why do they make liquid laundry detergent BLUE and why doesnt it stain my white shirts BLUE?
Best guess? There’s only enough colorant to make the undiluted detergent appear to be whatever color but not enough to actually dye washed clothing (at least under non-laboratory conditions). “10. Colorants and fragrances: Sometimes colouring agents are added to improve the appearance and fragrances may be added for a similar reason and to make the washed clothes smell nicely.” These colorants are different than ‘optical brighteners’. “The detergents promising making the laundry “whiter than white” usually contain optical brighteners, acting as phosphors converting some ultraviolet radiation to blue light and optically offsetting the yellowing of the material.” Perhaps there is a laundry chemist out here…
