The invention concerns a method of repairing manufacturing flaws in porous separator strips for storage batteries, whereby a repair material is applied deliberately to the flaw in-line during separator production such that the flaw is sealed, or whereby the flaw is heated at points in-line and thereby welded. Resins and/or polymers, dispersed in a dispersing agent, polymerizable materials and hot melts are suitable in particular as repair materials. Ultra-sound is preferably used for welding.