Back in December when my Invent came I had been searching online and found Nick Stewart, who has swatched every Diamine Inkvent calendar for years. I was captivated by his method. In January I dabbled in his Udemy course, Fountain Pen Ink art. I also bought some of the inks for that course that really seemed to separate chromatically in breathtaking, and beautiful ways. I’d taken a toe dip into the course, with the few inks I had, and the handmade cotton watercolor I’d gotten for Christmas. The paper is from Leather Village — 400gsm, rough textured, with those beautiful deckle edges. A simple test, with just a couple inks, to see what the paper and the ink would do together. The method to get the most chromatography from the ink is to lay down a lot of water, then drop in the ink.

The two graphites looked very different! Diamine Graphite is a soft, cool grey-blue. Robert Oster Graphite is dramatically darker, and look at that pink and teal fringe bleeding out at the bottom.That chromatography is lovely, with those hidden colors separating out as the water carries them across the paper.

I had also done this fun exercise, the Chromatic World in my Stillman and Birn Alpha sketchbook. You may have seen this in my “Early January 2026” post. You can really see how much Noodler’s Rome Burning in particular explodes when it hits water. That is one ink. One ink, water, and a circle. The gold, the ochre, the warm brown, the ghost of lavender — all of it was hiding inside Noodler’s Rome Burning, waiting for water to pull it apart. I find this genuinely magical every time.

When I was playing with ink in my recent food sketches, I got inspired to return to this course and do more extensive ink and paper tests. . Nick’s course uses mostly Bockingford watercolor paper, which I couldn’t source here, so I used what I have handy, and of course had to use different papers to see how they affect the results! I used the Stillman & Birn Delta, Strathmore Watercolor Paper 400 Series Cold Press 300gsm, and Arches Rough Watercolor Paper 300gsm.

The first exercise is the Swatch Painting. You lay a wave or swoosh down with a big round brush loaded with lots of water. Then drop in the ink with a smaller round brush and watch it travel. How much it separates seems very different based on the paper. I used four inks: Robert Oster Australian Opal Mauve, Noodler’s Rome Burning, Diamine Earl Grey, and Diamine Good Tidings, though the Good Tidings only made it into the Delta book.

The Delta paper gave me lovely fluid results. It actually holds up to these wet ink washes even better than with watercolor! Australian Opal Mauve separates beautifully, pulling apart into pink, violet, and that surprising electric blue is deeply satisfying. Rome Burning, which is brown as a writing ink, separates to this warm and golden ochre and lavender. Earl Grey is quieter, more restrained, a muted purple that bleeds to soft blue at the edges. The Good Tidings is the dramatic one of the bunch, near-black with that explosive teal bloom.

Look at the Australian Opal Mauve on the Strathmore paper!

The four inks are sampled on both Strathmore Watercolor paper, and Arches Rough Watercolor paper.

• Robert Oster Australian Opal Mauve
• Noodler’s Rome Burning
• Diamine Earl Grey
• Robert Oster Graphite

The Arches Rough gives a noticeably different quality — the texture of the paper surface shows through the ink in a way that the smoother Strathmore doesn’t.

The handmade Leather Village paper is a completely different experience. The rough fibrous surface grabs the ink differently, and the results are wilder and less predictable. Rome Burning in particular practically explodes on this surface. That ink has the best diffusion by far.

I tested the same four inks across all four papers, so you can really see how much the surface affects the results. Here they are side by side.

The final two exercises move into landscape territory, applying the chromatography technique to create actual pictures. Landscape One uses a large wet mass of ink for sky and atmosphere, with simple marks below suggesting ground and grasses. I used Australian Opal Mauve for both versions on the double spread. Nick Stewart Uses Robert Oster Barossa Grape, but I couldn’t find that ink.

There’s something about that ink in landscape form that feels almost otherworldly — those blue and pink separations read as light breaking through storm clouds. The little reed marks scratched into the wet wash at the bottom anchor it just enough to feel like a place. I had more dripping than I expected, but that is just practice. Wouldn’t this be great for snowy landscapes?

Landscape Two pushes further, adding more structure and a sense of depth. I used Robert Oster Graphite for this one, and it might be my favorite thing I made in this whole session.

The way Robert Oster Graphite separates in a wet wash — those deep plums, the pink spatter, the teal at the edges — makes a landscape that feels moody and atmospheric without any real effort to make it so. The ink does the work. That little glimpse of a structure in the negative space at the center, the misty ground below. If you blot the ink while it’s still wet, you get even more of that pink underlayer.

This Robert Oster Graphite is certainly the star player in this chromatography method! Honorable mention goes to Rome Burning, for it definitely separates well.