In 1892, Söderman started as manager of Kone ja Silta, which during his leadership grew the largest engineering company of Finland.

His parents were sawmill operator Karl Söderman, whose roots were in Kronoby, and Margaretha née Lybeck.

Soon after his birth the family moved to Pori[1][2] and onward to Kaunissaari[1] in Porvoo,[1][2] where the father became property manager of August Eklöf's steam sawmill.

[1][2] He funded his studies by doing drawing work and giving private lessons,[1] and participated in student organisational activities.

The widow Pauline Stenberg offered the company to Edvin Bergroth, who refused, as he had recently started as technical manager in Nobel Brothers in Baku.

In 1894 orders to Russia reached 1.1 million marks, which formed 80% of the total sales; in the following year the Russian orders were already 1.6 million marks, which made Kone ja Silta the biggest Engineering company of Finland in terms of gross value added.

[1] Dependency on the Russian market created problems when political tensions between the Russian Empire and Grand Duchy of Finland culminated in 1902: a political committee in Russia suggested that Finland shall be treated as foreign country in tariff policy which would mean high toll fees for Finnish products.

Finnish engineering companies became concerned and wrote a common letter which Karl Söderman and John Eager, manager of W:m Crichton & C:o delivered together to Vladimir Kovalevsky in Ministry of Finance.

The top year was in 1905, when the company benefited from increased orders due to the Russo-Japanese War; the GVA reached 6.2 million marks.

[2] He founded a common pension fund for Kone ja Silta blue and white collar workers and strove for creating a national accident and health insurance system.