Yup. I should post before and after pics of the next one I do. The effect is quite dramatic. Although it does vary a lot depending on the paper you are using. I have had two sketchbook where the effect didn't work well at all. Something about the way the paper does or does not soak up ink and water.

I discovered this style on accident years ago when I was testing all of my pens to see which ones bleed when wet. The goal at the time was to find the ones that *don't* bleed when you go over the lines with marker or watercolor, but the Pilot (my favorite writing pens for work) bled so dramatically that I was like, "Wait, that's actually cool." (I've also now tested various colors of Pilot pen and they all produce the effect a bit, but none as satisfyingly as the classic black ink. The "caramel" ink is my second favorite Pilot pen.)

This Staedtler fineliner also bleeds significantly and the brown color produces such a satisfying sepia look. (The Pilot ink doesn't change color when wet but the Staedtler shifts from dark brown to light brown after it's wet.)