New answers tagged plaster
Just use the plain cement. Mix water and cement and it should be half solid
You had it right with "skim over the top and sand flat". The only thing you want to do is scuff the paint gently with sandpaper to help the joint compound bite.
Before you attempt to repair it, make sure that the cause of the ice dam has been fixed. You may need to insulate the ceiling, and/or add a styrofoam vent baffle to the inside of the roof to prevent that area from getting too warm. Ice and water shield installed on the roof probably would have also prevented this from happening. The repair will depend on ...
Often, people talk about “old-fashioned horse-hair plaster,” but the binding agent in old plaster walls was more commonly cattle hair. -searshomes.org I am reasonably sure it's not asbestos.
In the end we called a plasterer and got it re-skimmed due to the surface being very poor (lots of the plaster came off in the paper removal process). Thanks for everyone's help, maybe it will help future DIY'ers.
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