The paintings of life in archipelago painted in bright colours were Collin's final breakthrough as an artist.Collin became a member of group of artists led by Tyko Sallinen.
The group took later the name November Group.
In middle of 1910-decade the group started to use more ascetic palettes, and the colour scale of Collin was the most minimal of them all.
He only used a few dark shades.After 1921 Collin gradually abandoned his gray and brown palette by adding more bright colours.
When he became older, his style became more realistic.Collin is known for his paintings of people.
Many of these illustrate literature, such as Aleksis Kivi's Seven Brothers or Cervantes' Don Quijote.
He portrayed factory workers and farmhands as faceless representatives of their social class.Collin was given an honorary title of professor in 1953.
He received the Swedish Prince Eugen Medal in 1957.