Is plaster better than drywall compound for skim coating? Before I saw that show about using plaster, I was planning on using the dry wall compound to skim coat the walls in the room we're going to be working on. What are the advantages and disadvantages of plaster and drywall compound for skim coats? Do you have to water down the plaster like I've read you do for the drywall compound? I'm planning on painting the walls a dark green so want to get the surface as smooth as posssible. Thanks for the help.