Liquid formulation comprises at least 3-iodopropargyl butyl carbamate (IPBC), n-octylisothiazolinone (NOIT) and a solvent (A) exhibiting a boiling point of >= 250[deg] C based on the standard pressure and containing at least two functional groups comprising ether, ester or amide or alcohol groups, where the formulation is substantially free of a solvent (B) that exhibits a boiling point of less than 250[deg] C. Independent claims are included for: (1) a technical material obtained by treating the technical materials with the formulation and (2) protecting the technical materials against the attack of and/or destruction by microorganisms, comprising contacting the diluted or undiluted formulation to the micro-organism or its habitat.
