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					Originally Posted by automaton 3  I've done boatloads of this work.  Lightly sand around the joints  on the painted surfaces first to promote adhesion.  Don't use hot mud,  it sets up fast and is a pain to sand. The general purpose mud is easier  to work with. If you buy it pre-mixed it you'll need to thin it down  slightly.  
 The paper tape has to have a thin  layer of mud behind it before application, then another thin layer over  top as your starter coat.  In our dry climate I tend to apply the tape  wet or pre-coated with mud to promote good adhesion.  Then add thin layers and feather the  edges (you should apply differential pressure on the knife to feather-  some really good youtube videos on this).
 
 Keep  in mind the goal is to create a very gradual hill over the seam so it  become imperceptible, and not to try to make it flat.  Do not over-sand.  Get a very bright light and  hold it cross-ways to your seams.  Anything noticeable will show up  after paint.
 
 Another tip.  If you happen to  get bubbles or lifting in the paper it won't disappear with more layers of mud,  that part of the tape probably has to be cut out and re-done.
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lots of good information thank you! I was thinking of using hot mud to pre fill the bigger gaps and just trying to leave almost nothing on the flat section like scrapping it all off except the gaps and regular mud for the rest. Seems like a lot of videos recommend this but not sure if its unnecessary.