This review is by Kalina Wilson, who can also be found at geminica.com.
It can be hard to find a good brown pen for sketching. While there are a lot of beautiful brown fountain pen inks, they aren't waterproof (with perhaps one or two rare exceptions). When buying a disposable brown pen, it can be hard to predict the color - they range from rusty orange to ashy sepia, and the color on the label or even the pen cap is often no clue to the tone of the ink.
While my collection is by no means exhaustive, this examination includes several of the most common and most recommended brown pen options.
The Candidates
Visual Comparison
In the line tests above, I pressed harder for the bottom three lines - you can see it clearly in the case of the Pigma Micron 05 Sepia. Note that some pens showed no variation based on pressure.
Like many Pen Addict readers, I'm a big fan of the Pilot Hi-Tec-C despite it seeming to be waterproof only on certain papers. At least when it runs, it runs in an attractive way which is usable for art. Note that the almost purplish hue of the Hi-Tec-C brown turns to something like burnt sienna when wet. I love these colors, though of course since it isn't waterproof I often don't choose it for sketching. Also see Pen Addict's Hi-Tec-C review for a writing sample in blue-black.
The Zebra Sarasa had some conspicuous problems while I was making the comparison chart above - it wasn't giving a consistent line. Since Pen Addict's reviews show good consistency with this pen, it may have been a rare glitch. I went through several test pages before it worked itself out, but now that it has I like this pen a lot and it allows for more line variation than most of the other options. I drew the more distant towers here lightly to imply distance - it's subtle but you can see the difference.
The Zebra Sarasa also does very well with water - I'd say it's totally waterproof. The "tea brown" color is nice and rich. All in all, a very good pen for sketching.
The Uni-Ball Signo DX in Brown Black is very consistent, has good ink flow, and is also almost but not entirely waterproof. On some papers, a little surface ink can pick up when the ink is still relatively fresh; you can see a slight cast here as I went over it with a waterbrush. The line isn't pressure sensitive at all, but like I said... consistent. I really like this one as a writing pen, actually. Without pressure sensitivity or a particularly rich tone it's not my favorite for sketching but is a fine pen albeit with some body issues (I agree with Pen Addict's assessment).
I had trouble with the Copic Multiliner in sepia. It's very pale, and the tone isn't strong or beautiful enough for me to want to use it for adding color. I really want to like it, since the Copic Multiliner is built to last - metal body, replacable tip, refillable - what's not to love? The Pen Addict agrees. This sepia (which is far from what I would call sepia) is the weak link in their collection, and I look forward to reviewing some of their other colors here soon - I've enjoyed those much more.
The Pigma Micron in brown performed very well though I've only found it in their 05 size, which is larger than I'd like, and I prefer less of a yellow cast. Still, totally waterproof and a good pen.
The Pigma Micron in sepia is much darker, but it's a tone I found very visually pleasant. It's a shame that once again I only had a larger tip (05) available for testing. See Pen Addict's thoughts on the smaller 03 size.
The Final Verdict
If it were even halfway waterproof, the Hi-Tec-C would have made it to the top due to its lovely purple-leaning tone and versatile line. Instead it is relegated to "special use" but can't be a primary tool. The Pigma Micron in sepia serves well as a warmer substitute to a black line. As a truly brown pen, the nice rich tone of the tea brown Zarasa won me over - that's the pen I'm grabbing when I'm laying down a brown line with some watercolors and want the line to sing.