Birmingham Pen Company is a small family-run business that makes fountain pens and fountain pen inks. While the company started with making fountain pens, it seemed their focus is now on inks.
Boysenberry is from the Swift Formula collection where the inks were designed to be wetter than average and performs well in a wide variety of fountain pens. This ink is a medium purple with shading and no sheen.
The ink has a very wet flow. Due to the wetness of the ink, it will perform well on some papers and worse on others. I think the ink will be more suitable in the finer nibs. On Leuchtturm1917 paper, there is hardly any shading and no sheen. I would avoid this ink and paper combination because there is a lot of feathering and bleedthrough.
This is written with a TWSBI ECO-T medium nib.
Disclaimer: This ink was purchased by me and all opinions/photos are my own. This post was not sponsored.