Now that the old oil tank has finally been removed, I'm starting to think about fixing up the walls in the basement. Today, it's a bit like an Eastern bloc warning down there. The walls are cast, and you can clearly see where each board in the form has been, with differences up to perhaps 10 mm. Does anyone know how to go about getting them ready for painting? I'm considering trying to apply plaster (plaster mix in a bag that mixes with water) but maybe that's too difficult if you haven't done it before? Other methods?
Plastering is not easy, but it can go really fast for someone who knows how!
If it's concrete, some masons usually prime with concrete water or concrete slurry as a base if it's a hard concrete wall. Then they throw/sling the plaster (which must have the right consistency) and afterwards, they smooth it out when the plaster has dried "just right" and it's considered "good to go" when it "feels right," meaning quite a bit of experience is beneficial. The mason I hired managed 12 m2 in 3 hours! but that was after I had cleared away all the loose material beforehand.
If it's concrete, some masons usually prime with concrete water or concrete slurry as a base if it's a hard concrete wall. Then they throw/sling the plaster (which must have the right consistency) and afterwards, they smooth it out when the plaster has dried "just right" and it's considered "good to go" when it "feels right," meaning quite a bit of experience is beneficial. The mason I hired managed 12 m2 in 3 hours! but that was after I had cleared away all the loose material beforehand.
I have done some plastering for my own sake, and as Lymmeln says, it takes time for those who don't know how. I have more patience than money 
I would have made sure to remove paint, etc., and then asked for a quote from a company for the work. A long straightedge is good to have if you don't plan to put any strips to pull off after.
I would have made sure to remove paint, etc., and then asked for a quote from a company for the work. A long straightedge is good to have if you don't plan to put any strips to pull off after.