Why did my etchings turn out so faint?

I spent hours just making the basic marking lines. I used 37% distilled vinegar, a lot of salt and even tried two 9v batteries connected in serial. It bubbled and hissed, and lefft a lot of green and black gunk, but when I wiped it clean the markings are so faint I can just make them out in the right light.

My pot is a bog standard stainless pot, nothing special about it as far as I can tell.

Any tips? If I can't come up with a way to make the marks stand out more I'll probably reach for the Dremel...