A while ago I did a sample swab with a pen friend, and Bungubox 4B was one of the samples I got in the swap. 4B stands for the four B's in BunguBox Blue Black. You can find this ink at Vanness Pens.
4B is a dark blue black.
In large swabs the ink has a beautiful coppery sheen.
Let's take a look at how the ink behaves on fountain pen friendly papers: Rhodia, Tomoe River, and Leuchtturm.
Dry time: 15 seconds. This ink has a great dry time for how wet the flow is.
Water resistance: Medium-some of the ink washed away but you would probably still be able to read it.
Feathering: Low-the ink feathered a little bit in the flex nib on Rhodia, I think mainly because the ink is so wet.
Show through: Medium
On 20 pound copy paper the ink behaved well, no issues that I noticed.
I used a Pilot 912 with an FA nib then switched to a medium Pelikan M800 Renaissance Brown on Tomoe River paper. The ink had a lovely wet flow.
I really like the flow of this ink, but the ink does have a slight chemical smell.
Overall, I really like this ink. It's an interesting color, dries fast, and has some interesting sheen. Give it a try, you might love it.
Disclaimer: I got this ink through a sample swap, and all photos and opinions are my own. There are no affiliate links on this page.