SDS Studio™Definition: The summation method classifies a mixture by adding up the concentrations of its classified ingredients and comparing the sum with the CLP thresholds of each hazard class.
Example for skin irritation: if Skin Irrit. 2 ingredients plus ten times the Skin Corr. 1 ingredients reach 10 %, the mixture is H315. Environmental hazards add up ingredients weighted by their M-factors.
Not every class is additive. Sensitisers, CMRs and STOT are classified when a single ingredient exceeds its own limit.