We had noticed paint alligatoring in the bathroom so we stripped this down and then we applied a 'skim coat'. BUT, the skim coat turned out to be this:
unipro Universal skim coat which is a floor patch. We bought the wrong type of skim coat. So can we paint over this directly or do we need to sand it down and put on a plaster or joint compound skim coat? Would a good primer such as Kilz or Zinsser?
Once it has cured you should be alright surfacing it and putting on a good latex bonding primer. I would use Benjamin Moore Fresh Start or MAB Superbond. You could also use an alcohol based masonry and concrete primer but I don't think you need to. Do not use an oil-based primer on a concrete surface though. The alkalai in the material will react unfavorably with it.