Re-skimming old plaster repair: first with sand+cement or just finishing coat

Sometimes it's a 'filter' Bianco. Someone who is determined will do it anyway, regardless of the naysayers. I will always try and encourage someone to have a go...although certain tasks take a bit more effort. Plastering isn't the hardest...but there are many variables and although there is an almost romantic notion that with a new trowel and a couple of bags of plaster...everyone will marvel at my beautiful flat wall, the reality for many is severe frustration when the finish comes out looking like the bay of biscay. From the initial pic of the ops flat, there was some nice period features that you could compromise by messing it up. I can plaster, but I don't always do it myself as sometimes it's better to leverage your time getting someone else to do it. Just my opinion..and he hasn't come back so far with 'I'm gonna do it regardless attitude'...hope he does

 

Is that lime plaster? If so, you want to repair with lime ideally. Gypsum repairs will probably crack and move away from the original lime in time. You also should look into using the right materials to keep the property "breathing" as it was designed to. Old houses are built so differently to modern buildings and really need old style repairs to stop future problems from creeping up. damp, cracks etc

On the bright side, lime gives you a lot longer to work with than modern gypsum plasters so it's better for the beginner!