The present invention relates to a process for manufacturing thermal and/or acoustic insulation products based on mineral wool, especially on rock wool or glass wool, bound by a sizing composition based on a thermosetting resin, in particular of resol type, which aims to limit the emissions of formaldehyde.The method is characterized in that it comprises a step that consists in applying a composition of an agent capable of reacting with formaldehyde, chosen from compounds having active methylene(s), to the insulation product, after the thermosetting resin has crosslinked.Another subject of the present invention is the device for carrying out the aforementioned process and the insulating products based on mineral fibers that are obtained.