That’s right – colour!
Ladt week, at the Hirschsprung Collection in Copenhagen, a shocking discovery was made! Take a look, bottom right:
Pink! A pink room! By Hammershoi!!!
The label says ‘Interior in Louis XVI style. From the artist’s home, 1897. In that year, the Hammershois moved into a newly built apartment, Aahuset in Aaboulevard, Copenhagen, where, presumably this was painted.
Interestingly, when Hammershoi moved into Strandgard 30, he insisted on having the walls repainted to the muted palette that he became most associated with.
This definitely needs more investigation!