[1] After his political career Hörhammer was one of the leading art gallerists in Finland.

He worked at the Swedish-language newspapers Arbetaren, Social-Demokraten and Arbetet and published the monthly Folktribunen.

[1] In 1915, Hörhammer was sentenced for six months of lèse-majesté for an article published in Arbetaren in November 1910.

[3] After his prison term, Hörhammer left politics and became an art dealer.

He was the chairman of Finnish Chess Federation and FIDE awarded arbiter.