Styrene-acrylic resin solution in water emulsion. The product is characterized by a blue coloring, quick drying of the film, excellent penetration, adhesion to the substrate and absence of surface stickiness. PRIMERGUM is used to glue to the substrate the non-woven synthetic fiber fabric ARMO 100, used as a reinforcement when waterproofing with IDROGUM o FYBRO HP. PRIMERGUM can be used as fixative to the substrate without the use of mesh for very irregular surfaces which do not require the application of a reinforcement.