I've been wanting to add a document stable brown to my collection of ink. I plan to use it mainly for line art in Ink & Wash sketches in place of Carbon Black. Just so I have some variation.
A week or so ago I sent off for the following sample inks:
In addition, I ordered a random sample, and was sent Robert Oster Brandy ink.
I set up the ink vials in a test tube tray. Using watercolour artist trading card sheets, I swatched and labeled each one. After showing them to the folks in the studio zoom, someone suggested I include some crosshatching with each of them.
I taped the watercolour paper swatches in my Ink Journal, p 68.

Ink swatches on watercolour ATC paper.
You can see some crosshatching tests to determine how dark or light it will be with the associated ink.
I also made swatches on the cream Leuchtterm paper:




