Laybond Universal Primer RWS083B This product comes in 5 litre bottles and is used by floorlayers to seal and prepare the sub surface of the floor before laying the screed. This primer provides the best adhesion to the floor for the screed and if applied to surface provides greater grip for any adhesive being used. This is a product that should be used if you are giving any long term warranty on the work. Be a professional fitter. Laybond Bostick universal primer may be mixed 2 parts water to 1 part primer to form a key to the surface for adhesive tapes or other adhesives.