cracked corner joint

[Walin]

1) As I was removing corner joint tapes, I noticed that many cracks that I had repaired before reappeared on corner joints (corners with or without corner joint tapes). I had been repairing these cracks for about 3-4 times already. What should I do to rectify this problem?
2) For corners without any corner joint tapes, do I need to remove the cement/filler so I can put corner joint tapes on.
I am really frustrated as no decorators/builders were interested in this small job.
Can I have some advice please? Thank you.

 

[PrenticeBoyofDerry]

Yes rake out the joint so you can then fitting the corner tape, for larger cracks/gaps it is advisable to overlay the first tape with a second one, this will help reinforce the bond.
The tape can then be either plastered and feathered out to existing walls or easyfill (this requires two or three application and sanding down after each application has dried).

 

[Walin]

Thanks. I will do that.

 

[Walin]

After I removed the corner tape:-
a) one side shows the plaster board with paper and a thin layer of filler on top, I tried to remove the filler so the surface is flat. Is that enough or do I have to
remove all the grey filler above the plaster board paper? How can I do it faster? At the moment I am using filler knife.
b) one side looks grey, I tried to remove it but it's difficult as it's a very thin layer with paper underneath it. It sounded and looked like a plaster board to me.
However, it looks different from the other plaster board. I do not think I can remove the grey layer.
Why I am asking this is because the instruction for product use on the easy fill packet mentioned "Not to apply over a previous air coat material"? Can I apply easy fill on top.

Can you please let me know whether my steps of putting on mesh corner tape is correct:-
1) Use joint filler to fill all the gaps between joints to provide perfect joint surfaces before putting on corner tapes;
2) Put on corner tapes on all the joints with the help of a filling knife; For wider gaps, use two layers of tape;
3) Apply 1st layer of easy fill on top and sand down once it is dried;
4) Apply 1 or 2 more applications if necessary and repeat the same process:
5) Job done

Thank you for your advice. Hope others can benefit as well as more and more people will be living in flats.