I had hoped to have a nice dark ink on this paper, using a fountain pen filled with waterproof ink. The ink is waterproof, but it is so pale I fell asleep. If you are going to do a line drawing and then color it in, you need to have a dark ink. The ink was definitely waterproof, but so what if I don’t like the result?
I also used my cellulose paper sketchbook for this, and once more I am not happy. All these blobs of unabsorbed color and a few more than many times using the hair dryer.
Maybe I am not being realistic about the paper, but I am realistic about the point of this study – is the ink waterproof? And that answer is yes. Goal met.
Ink, Yarn & Beer 
Is dark waterproof ink not a thing then? I like the painting anyway.
Waterproof ink comes in different colors – but this stuff looks dark but is really a grey. Nice for handwriting, or even sketching, but not for ink and paint. Wah! But glad you like the sketch!!