I’m reviewing the newly issued Sailor Souboku pigmented blue-black ink. I believe Sailor has now removed the hyphen, so I’ve written it as Souboku.
I started writing with a Lamy M nib, but found Souboku looked more saturated with my Parker 45 cursive italic nib. It’s a much more traditional shade of blue-black than Seiboku, and dried into a quite sombre blue-grey/black
Souboku has medium saturation and wasn’t so saturated that I couldn’t see any shading. It has some shading but not as much as Seiboku. Like Seiboku it can also occasionally exhibit some red sheen with wetter flowing nibs, especially on Tomoe River paper.
Flow was reasonably good, though felt dry. Lubrication across the page was smooth, but gave me more feedback with the same nibs that I had used for Seiboku. Lines were all crisp with no signs of spread or feathering.
Souboku didn’t suffer from any hard starts or non-starts when I put the uncapped pen down to do swab tests, dry times and water resistance.
It dried within 18-20 seconds on the Clairefontaine Triomphe paper and didn’t smear after it was dry.
It exhibited show through and bleed through on my cheap Banner writing pad.
I didn’t experience any clogging in my pens and saw no “crud” on the nib, but I didn’t leave this ink in my pens for a long period of time.
Clean-up out of my pens and converters took much longer than normal, even longer than Seiboku, and I used warm water with a drop of liquid detergent added.
However, it washed off of my hands with one wash.
I noticed that Souboku forms globules inside the sample vial and the converter whereas Seiboku coats the insides of both and covers them completely. Shaking Souboku simply makes more globules. Therefore, I would recommend not shaking pens that have converters filled with this ink, as it’s much more likely to get air bubbles down into the feed.
Another difference that I spotted between the two inks was when I was cleaning the pens in a sink of soapy water. Souboku cleaned off of the nib just while the section was lying in the water, but Seiboku had to physically be wiped off the nib before the nib came clean.
Souboku is waterproof, even under running water. However it caused small “spread” marks when I brushed through the water with a cotton bud.
Available in Sailor 50ml glass bottles from several sources worldwide.