what kind of herbicide leaves a yellow coat and doesn't wash away with rain?

I don't personally use herbicides, but often times people that do use herbicides add a "spreader-sticker" product to herbicides, to "make them be more effective", and I think this would cause the yellow coat and is intended to keep it from washing away with rain. These spreader-sticker products can be added to any herbicide, so the presence of this doesn't help tell you exactly what herbicide was used.

If I ran the world I'd banish chemical herbicides, so if you want information on what "good" herbicides do, you will need to get that elsewhere. :)