One-component primer based on polyurethane resins in an organic solvent. Recommended for the preparation of substrates made of cement and anhydrite screeds and concrete before the application of polyurethane, polyurethane-silane and epoxy-polyurethane adhesives (e.g. BONIPUR PARKIET 2k, BONIPUR PARKIET 1k, BONIPOX PARKIET 2k ECO and BONIPOX PARKIET 2k). The preparation penetrates deep into the primed substrate, strengthens it, while binding the remains of dusts and micro-dusts. Primer can be used on heated substrates.