Abstract: A fibrous material, such as fiberglass insulation, is treated to minimize the generation of static electricity when subjected to agitation, such as by sawing, chopping, blowing, etc. during manufacturing, handling and/or installation, by applying an anti-static composition onto a mat of the material during the manufacturing process. The anti-static composition preferably is an aqueous solution containing an active anti-static agent including a nonflammable glycol humectant and two water soluble quaternary ammonium compounds, one serving as the primary anti-static ingredient and the other serving as a corrosion inhibitor and stabilizer. The anti-static composition is sprayed onto the surface of the mat as it travels through the cooling zone and the cooling air drawn through the mat causes the anti-static agent to penetrate through substantially the entire thickness of the mat.