Review: Akashiya Sai watercolor brush pen

I like being able to add grey tone to my pen sketches sometimes, so in addition to regular black brush pens, I’m always on the lookout for good grey brush pens.

Akashiya Sai Watercolor brush pen -- mouse gray
Akashiya Sai Watercolor brush pen — mouse gray

Akashiya Sai watercolor brush pens come in a variety of colors, but to start off, at least, I was only interested in their grey.

Initial test.
Initial pen test on printer paper.

All of the grey brush pens I’ve used up to this point were felt tipped, so I was actually pretty surprised to find that the Akashiya Sai had synthetic bristles, making it much more like an actual brush. The bristles are just under a centimetre in length (so just slightly shorter than a Pentel pocket brush), giving the pen a good range of strokes.

It handles as well as any other synthetic bristle brush pen, but it doesn’t take cartridge inks, and so, is disposable.

Akashiya Sai watercolor

The ink is Copic-proof when dry, but as a “watercolor” brush, obviously not waterproof.

Akashiya Sai watercolorFlow is unsurprisingly wet and dry time is on the higher end for brush pens, but it’s possible to get a slight drybrush effect on thick strokes, and that’s something I’ve never been able to do with a grey pen before.

Being able to make the same sorts of strokes and use the same sorts of techniques I normally do with my other synthetic hair brushes, but in grey, is fantastic.

Akashiya Sai watercolor

Even as just a grey brush pen, the Akashiya Sai is lovely and well worth it, in my opinion. But it’s a watercolor pen, too, so I was obligated to do some thorough testing with water!

Pen test on 65 lb/176 gsm cardstock.
Pen test on 65 lb/176 gsm cardstock.

Of course, water testing is very affected by paper. Since it was on thin printer paper, adding water to the initial pen tests destroyed the paper before it got the grey to really blend, run, or fade. For my second test, the above, left-facing horse, I inked with a Zebra brush pen and Pentel pocket brush on 65 lb cardstock, which I often use for pen and Copic drawings, but not watercolor.

But adding water to that once again warped and disintegrated the paper before it did much of anything to the grey laid down by the Akashiya Sai.

Pen test on 140 lb/300 gsm Arches coldpress watercolor paper.
Pen test on 140 lb/300 gsm Arches coldpress watercolor paper.

So proper watercolor paper was needed! 140 lb is pretty standard. The above is Arches paper, but I also use Strathmore regularly. Finally, adding water doesn’t ruin the paper, and the grey is able to blend!

Once the pigment on the page is wet, it moves around similarly to watercolor, though it feels a bit weird at first? When regular watercolors, you’re adding pigment and water at the same time, so moving the pigment around on the page is easy — the water is a built-in vehicle. With the pigment laid down at the start via the Akashiya Sai, you’re pushing around dried, or semi-dried pigment with only water, so you have to put down more water to start with to pull the pigment off the page.

Akashiya Sai watercolor

Once the page is wet and the pigment is moving though, it feels pretty much like watercolor. As with real watercolor, the pigment laid down by the Akashiya Sai is pretty forgiving — if you let the paint dry (even for a week or more), and then wet it again thoroughly, you can push the pigment around again. Honestly, I was pretty impressed.

I used a Yasutomo Niji water brush to add water, if you were wondering, but any regular paintbrush dipped in water would’ve been fine for my purposes here.

See how the pigment gets washed completely out of the brush?
The pigment gets washed completely out of the brush if you try using it on wet paper.

The main downside of just adding water to the Akashiya Sai pigment is that you have to add so much water to blend it that you loose a lot of your original brush strokes. Wet on wet techniques don’t really work either, as the water on the page will take away your control of where the pigment goes, more so than with real watercolor, since you can’t control the amount of pigment coming out of the brush.

Also: putting the brush to wet paper will wash all the pigment out of the brush completely, and it takes a while for the pen to recover — you have to keep using the brush on dry paper to get the ink flowing properly again; if you just set the brush aside, the ink won’t flow again on its own. It’s a bit of a bummer!

Another pen test on 120 lb/300 gsm watercolor paper (Strathmore, this time).
Another pen test on 140 lb/300 gsm coldpress watercolor paper (Strathmore, this time).

Still, the Akashiya Sai gives you a great option for detail work on top of looser washes.

After the first pass of water over your grey brush work, you can wait for the page to dry, and then go back to it again with the watercolor brush. The ink/pigment flow from the pen is fairly consistent, which is great for details since you don’t have to worry about “refreshing” your brush with the perfect balance of pigment and water over and over again as you work.

Daniel Smith watercolor paint on 140 lb/300 gsm.
Daniel Smith watercolor paint on 140 lb/300 gsm coldpress watercolor paper.

I used Daniel Smith watercolor over the same ink drawing (lightboxed) to compare. The Niji waterbrushes also have synthetic bristle tips, though these brushes are pretty worn out and old, so I suppose they’re at a bit of a disadvantage for detail work, even before water/pigment balance issues. But these are actually the brushes I use on most of my watercolor paintings at the moment, so.


Akashiya Sai watercolor brush VS Daniel Smith actual watercolors.
Akashiya Sai watercolor brush VS Daniel Smith actual watercolors.

I think it’s pretty clear that I had a superior level of control and finnese over the darkest parts of the painting with the Akashiya Sai. The slight drybrush affect achievable with the Sai also adds a little something to the first painting that’s much harder to replicate with real watercolors, especially with the waterbrushes I’m using.

The Akashiya Sai watercolor brush is honestly pretty amazing and I’m really happy with its performance, but I don’t think they’re a replacement for real watercolors.

Zebra brush pen and Akashiya Sai + small amounts of water in my sketchbook, which has pages of a similar weight to Bristol board.
Zebra brush pen and Akashiya Sai + small amounts of water in my sketchbook, which has pages of a similar weight to Bristol board.

I only have one color right now, so I have no idea how well different colors of the Akashiya Sai would blend together, but there’s really no possible way they could blend in the same way that actual watercolors can. You mix watercolor paints on a palette before putting it on the page, ensuring you have the colors you want before any pigment is on the page. With the Sai brushes, even if you mixed your colors on a separate page, there’s a much more limited amount of pigment you could mix, and it’d be much harder to replicate the color between painting sessions, if needed.

I think doing a full painting with these brushes would be really frustrating and limiting, though they might be nice to use on top of watercolor paintings to finish off details. (Though you’d definitely want to check that the colors match — as demonstrated, Akashiya Sai’s “mouse gray” is completely different from a Payne’s grey.)

Pencil and Akashiya Sai + water in my sketchbook.
Pencil and Akashiya Sai + water in my sketchbook.

But for sketches, studies, and speedpaints? The Akashiya Sai sets could be an amazing tool. They’re much easier to use and set up than the most portable of watercolor paints and bring along the best mark-marking abilities of the brush pen world as well!

I think they’re a decent place to start, too, if you’re intimidated by real watercolors. At $3.50 a pop for singles, ~$10 for sets of 5, and ~$30 for the full set of 20, they’re much, much cheaper than all artist-grade watercolors, haha.

About the author

Kiri is an artist, writer, and (brush) pen enthusiast in Seattle with over 12 years of convention vending experience and an inclination towards verbosity.