(Susan M. Pigott is a fountain pen collector, pen and paperholic, photographer, and professor. You can find more from Susan on her blog Scribalishess.)
Montblanc Toffee Brown is a gorgeous brown ink with lots of character. It comes in a hefty Montblanc bottle with the MB star on the cap.
Some describe the bottle as a shoe shape. I honestly don't see a shoe–if it is a shoe, it's a clunky one. I just assumed that the shape was practical: you have a smaller reservoir when the ink runs low. But that will take a while. This bottle holds 60ml of ink.
The ink flows well, has no detectable odor, and no negative qualities that I could find. When compared with my two other brown inks (Iroshizuku Yama-guri and Tsukushi), Toffee had shades of green and pink in it. Yama-guri is more of a black-brown, and Tsukushi is a reddish-brown. Toffee is what I would call a golden-brown, though it does have pink/red tones.
Montblanc Toffee is now the standard ink for my M800 Tortoise with its triple broad oblique nib. Oh. My. Gosh. Just look at that shading! It has gradations from dark brown to toffee (thus the name).
The ink is not waterproof. Its dry times depend on the width of your nib, but the ink seems to be pretty wet. With this kind of shading, though, I don't mind waiting for the ink to dry.
I never thought I'd be a "brown ink person" (I gravitate towards blues). But I also tend to be a little OCD about inks matching my pens and vice versa. So, for my brown pens, I use brown inks. Toffee Brown has replaced the Iroshizukus at least for my broad nib. The color and shading are simply outstanding. But for my finer nibs, I still like Yama-guri and Tsukushi. I guess I just need to buy more brown pens!