Calluna was born basically by accident.
When I needed a little break from creating Museo I was simply fiddling around a bit to see if maybe a full slab serif would be something to have a look at. The first thing I did, of course, was to put slab serifs on the stems of Museo. When I did, something nice took place. Slab-serifs with an instructions! I ended up utilizing the idea for something I constantly wanted to do: making a rather serious text face. The goal was to make a text font, however one with adequate interesting details.
In the end it all boiled down to discovering the balance in a typeface in between toughness to function as a text face text and having enough refinement to look excellent as screen font.