My house is around 60 years old and has plaster walls and ceilings. Many seams in the plaster are visible. The seams are sunken in. I was hoping to be able to skim a coat of compound over the seams to fill them in, but I've never done anything like this with plaster. The walls and ceilings are painted with latex paint. Can this be done? If so, is there a special compound that I should use?