system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How comes that no matter what colour the gel in soap products, the lather is always white?
gpt
Lather is white because it's full of tiny bubbles!  When you whip that soap into a foam, what you're really doing is mixing lots and lots of air into it, until what you're seeing contains way more air than soap.  (And consequently, way more air than the dye that gives the soap its color.)  Those itty bitty bubbles reflect a lot of light, which makes the lather appear white.  If you added a LOT of dye to your soap you could get some color into your lather, but at that point it would definitely stain your hands, which kind of defeats the purpose of soap.