Plaster repair is a process that’s typically done by plasterers. It involves removing the existing problem plaster, then applying new layers of plaster over it to create an even surface and cover any discoloration or stains left behind. There are some DIY options you can try if your ceiling isn’t too damaged; however, they may not work for a large section of the plastered surface and you’ll need to have your plaster repaired by professionals if that’s the case.