I recently purchased an old 1930's farmhouse that has plaster and lathe throughout. I love old stuff and am trying to just work with the plaster. We've removed the wallpaper and I'm down to just the plaster, which is rather inconsistent and wavy along the wall. There have been doorways over the years that have been filled in or moved, so the wall changes there and the patch job is a litte...well, a lot uneven. What steps need to be taken prior to painting with a latex paint? There are patches of what looks to be a cement product on the wall currently which must have patched areas when the wall was prepped for wallpaper in 1963 (walls are signed). Is there a sort of compound like for drywall? A heavy-build primer that will fill in some of the small cracks? Any suggestions would be appreciated.

Drywall compound will work. I would skim coat the walls with a broad trowell to flatten it out a little. If you have large cracks, reinforce them with some mesh tape before you skim coat. I would not depend on a high build primer to fill cracks. Part of owning an old lathe and plaster home is a tolerence for less than perfect walls. Short of drywalling over it, lots of elbow grease and patience is the route to flattening out the walls.

Thanks Maintenance 6. I appreciate your response. I am in no way trying to get the perfect wall...I think that would be darn near impossible, but I would like to do the best I can to make it nice. I will try the mesh tape and skim coat. And, then just a standard primer?