It is because of the molecules that are present in the food. If we rub our hands in egg-yolk, it will not stain our hands. This is because the egg yolk molecules are very large and do not stick to our hands. However, things like grass, wet paint or food colouring will leave a stain on our hands. The molecules that comprise these items are small and stick to our skin well. Food colouring is made from miniscule particles that get into small crevices and pores of our skin, forming chemical bonds that allow them to stick to our hands, thereby staining them.
Why do some foods/things stain your hands?
