[1][2] From 1939 to 1940 Dumas Oroño studied at the National Institute of Fine Arts [es] in Montevideo, thanks to a scholarship from the Municipality of Tacuarembó for winning the Departmental Artists' Contest.

He was among the organizers of the Show for Liberties held in 1984 by the Uruguay Association of Bank Employees [es] (AEBU), towards the end of the 1973–1985 civic-military dictatorship.

[3] In 1959 he invited other artists from the Torres-García Workshop to create a mural gallery in the Liceo Manuel Rosé [es] building in Las Piedras, a work that remained there until 1964.

[3] Of communist ideology,[6] during Uruguay's full civic-military dictatorship, Oroño organized activities such as "cultural Saturdays" for students and neighbors, held in his own workshop in 1980 with the presence of José Pedro Díaz and Víctor Manuel Leites [es], among others.

In 1984 he also contributed to "La peña de los viernes" at the Casa del Autor Nacional, days in which several Uruguayan authors participated.