Abstract: Paper sheets, such as for use as the cover sheet of gypsum wallboard and the like, are rendered mildew-resistant by adding to the paper at the calende calender rolls an aqueous dispersion containing a heavy metal salt of quinolinolate, a paper coating binder and a colloidal suspending agent. A particularly preferred aqueous dispersion contains about 5-40% of a 30% active copper-8-quinolinolate paste concentrate; about 3-30% of a wax binder, preferably about 5-60% of an about 50% active wax emulsion such as of PARACOL 404 R; and a small amount of a generally non-thickening colloidal suspending agent preferably a xanthan gum.