Uneven ceiling

[soparklion11]

Someone re-taped and mudded some seams in my ceiling. But they're somewhat uneven - they look like speed humps when natural light hits them on an angle. There are no cracks in the ceiling.

Can I feather joint compound onto the painted ceiling? It is standard flat white ceiling paint. Would I need to sand it or prime it for the joint compound to bond to the paint?

Alternatively, can I just caulk the low points? I did something similar to a wall crack that kept opening over and over - my foundation has carbon fiber straps to limit flexion/contraction but they still move a bit each year. Yes, I've done a ton with exterior water control. Most of my neighbor's have the same issue.

 

[bud16415]

You can take a wide mud knife and feather out new mud right over what you have. It will stick fine. Then sand with a flat sander pad on a long broom handle. Then paint.

 

[joecaption]

Could be lots of different issues going on.
5/8 drywall was not used, so there's always going to be high and low areas.
To narrow a knife was used.
Improper sanding was done so the edges where not feathered out.
Any repairs needed to be primed and the whole ceiling also would need repainting at least one coat to get it to match.
Hard to say without being there or at least a picture.