Orion has over 1000 managerial personnel in Espoo, Turku, Hanko, Kuopio and Oulu.
The next company that will be hit is the Neste Oil group, followed by Gasum Oyj and Oy Aga Ab.
Managerial staff within the sector do not have their own separate labour agreement, as do other employee groups.
The Federation of Professional and Managerial Staff (YTN) and the Chemical Industry Federation of Finland (KT) met for talks Monday evening, but were unable to reach agreement on averting the strike. Negotiations may possibily resume on at the weekend.