I did mine by 1.) taping the corners 2.) apply the second coat one angle at a time 3.) used a sanding sponge I bought at Home Depot. The sponge has a sharp 90º edge that makes a very nice and sharp corner. I would suggest wearing cotton gloves when using the sponge. After using one for a day non stop, I had raw fingers.
Agree with MikeKy55. The corner trowels are junk in my opinion. And final sanding with a sponge (go ahead and sand with a pole sander first) will make for a great job. And he's correct about the gloves if you have a lot to sand. I've had my fingers bleeding before after "hand sanding" a big house (300 sheets or more). Years ago when I went to get fingerprinted for a concealed carry permit, the lady asked what kind of work I did because it took 2 or 3 tries to get a decent print of my right thumb, index and third fingers. Years of sanding without gloves had kind of worn them off.....
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