I found a royalty-free reference photo of a flower with a purple tint around the edges of the petals and also with wavy edges of the petals. Thought it would be a good subject for this type of ink drawing. I drew the flower in pencil and then used a fountain pen with a fine nib for the outlines. Then used a seni-dry micron pen for the hatching lines around the edges of the petals. I'm pretty happy with it.
When I tried this before using the fountain pen for the hatching, I found that the fountain pen gave out too much ink (the paper is also just cheap sketchbook paper so it's quite absorbent) and made it hard to get wispy marks. But it can still work.
Here are some attempts with the fountain pen. I did not put effort into the drawing (just drew without a reference) - just the hatching.
I could also try using a very fine nib on a dip pen and ink. I haven't done that yet.