Brush Pens, Part 4: Water-Soluble Bristle Tips

Guest review by Tina Koyama

This fourth and final installment of the brush pen series reviews bristle-tip pens containing water-soluble ink. Similar to their waterproof ink counterparts, these 10 brush pens have actual synthetic hair tips that take a bit of practice to get the hang of controlling. However, I find their lines to be more expressive and fluid than felt tip brush pens, so it is worth it to me to give them the extra effort to use.

water soluble bristle pens

Ink Color & Permanence

First, I’ll talk about the inks these pens contain. While they all look within a comparable range of black on the Canson XL 98-pound mixed media paper I scribbled on, the Kuretake Zig Clean Color Real Brush Pen has a slightly purplish tinge (which is more apparent when washed with water). The Zig, the Pentel Standard Brush Pen (medium tip) and the Akashiya Sai Watercolor Brush Pen have the darkest, richest washes when water is applied. That’s a quality I look for in water-soluble inks, since I generally use them when I want to take advantage of the wash for shading.

water soluble bristle wash test

Compared to some of the water-soluble pens in the felt tip group, these inks mostly stayed water-soluble when washed a couple of weeks after the initial line had been applied. However, when I washed them again just now, more than a month since the initial application, all of them were nearly permanent. I think it’s safe to assume that these inks eventually become permanent over time.

field notes water soluble bristle brush tests

All inks behaved as expected on Field Notes 60-pound Finch Opaque Smooth paper with very little bleed-through except where I had applied water. As I mentioned in the water-soluble felt tip review, it’s interesting to see the difference in the washes when comparing the Field Notes paper with the 98-pound Canson paper. Sized for water media, the Canson paper brings out the washed color, while the Field Notes paper makes the washes look more like wimpy blurs.

Although I tested only pens with black ink, it should be noted that the Akashiya Sai comes in 20 colors and the Zig Clean Color comes in 80! They can be blended like watercolors, and since they remain soluble for quite some time, you could continue blending them as you work. The Akashiya Sai ThinLine is available in five dark, natural tones. (I think I’m going to have to eventually get all five because I love the muted tones, which aren’t easily found in brush pens.)

Beyond these points, none of the inks stood out with any distinction. What I find distinctive about this group is the wide variety of form factors in which the pens are available.

water soluble bristle pens variety of form factors

Variety of Form Factors

By form factor, I’m referring to the size and shape of the pens. The three Sailor Fude Nagomi brush pens (the red, the green and the black) look the most like traditional Asian calligraphy brushes with their longer length and tapered body. (Incidentally, the three Nagomi pens are identical except for their body colors; I guess I would have known this before buying all three if I’d read the descriptions more carefully and hadn’t been so excited about having more brush pens to explore!)

Yellow Akashiya New Fude Disposable on 140lb Watercolor Paper
Yellow Akashiya New Fude Disposable on 140lb Watercolor Paper

The Kuretake No. 30 Double-Sided Brush Pen has a firm felt-tip on the opposite end of the brush (a nice option that was offered on several of the water-soluble felt tip pens).

The Akashiya Sai and the Akashiya New Fude Disposable Brush Pen look similar, both with transparent caps, but are longer than the Kuretake Zig Clean Color, which is slightly thicker. The Akashiya ThinLine, however, is indeed a distinctly thin pen – a little too thin for my comfort. It could be mistaken for an eyeliner. The brush itself is somewhat thinner than the others in this review, but because of that, I missed the wider end of the range that I could get with the others. Its very tip was not any thinner than the other tips.

Sketched with Sailor Profit on Stillman & Birn Epsilon paper.
Sketched with Sailor Profit on Stillman & Birn Epsilon paper.

The Pentel has a reservoir and a soft barrel that can be squeezed to push more ink to the brush. (Beware: this is the type that will leak to high heaven at high altitudes.) It is refillable, however, with proprietary cartridges. The only other refillable pen in this group is the Sailor Profit Brush Pen, which looks like and is refillable like a Sailor Profit fountain pen.

The variety of shapes and sizes means that you can choose the one that fits your hand and work style most comfortably. If you are already familiar with a classic fountain pen body, then the Sailor Profit is an easy transition. If you like narrow barrels, then the Akashiya ThinLine might be a good choice. The Zig Clean Color has a body that feels the most like a classic marker, and I find the thicker barrel easier to use. The longer Sailor Nagomi pens might be difficult to handle, but they are nicely balanced even when posted.

Final Impressions

I’ve done it in all the other reviews, so I might as well complete the set: I am notably grumpy about caps that don’t post as expected. In this group, only the double-sided Kuretake has caps that must be reversed to post. All others made me happy by posting predictably.


While I tend to reach for waterproof inks more often, I have to say that the water-soluble aspect of these bristle brush pens encouraged me to experiment more. Most of my sketch samples in this series were done with brush pens only. For this review, however, I tried something different by sketching the pear first with oil-based Faber-Castell Polychromos colored pencils. Then I gave it shading with the Pentel, which I further blended with a waterbrush. The wash has enough transparency that the blended colored pencils underneath show through – an effect that I like.


I wore out all three Sailor Nagomi pens at life-drawing practice sessions. The expressiveness of the brush combined with the ability to conveniently shade by washing the line made them a joy to use.

While no clear favorite emerged from this group, this combination of brush and ink type is definitely a keeper in my sketch kit. In fact, as a result of writing this series, I now have four daily-carry brush pens, one of each type, because each serves a different sketching need.

If you missed the other parts, they are:

tina-koyamaTina Koyama is an urban sketcher in Seattle. Her blog is Fueled by Clouds & Coffee, and you can follow her on Instagram as Miatagrrl.

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