had a small area of wall bricked up then covered with a cement mortar and a finish of plaster. Just a ready mix type I think, and it was dry in 2-3 days. I then coated it with a general primer with a view to coating it with emulsion. The primer has given a sheen like finish which the emulsio just runs off...what next???
lat42, There should be no need to use a special primer on this new finished plastered surface and do not use undercoat as recommended by stonyboy, as the wall has had a backing coat of sand and cement this wall will be alkaline by nature and this will saponify the oil in the undercoat and will lead to problems later. If as you say you have used an all purpose primer then this should be okay but don’t use emulsion straight on top, after rubbing down, use a coat of water based acrylic primer which will adhere better than emulsion and is more flexible you should be able to emulsion directly on top of this.