This story covers finishing drywall butt joints with three-coat system.
The long edges of drywall sheets are tapered. Two tapered edges together form a depression, which makes it possible to create a flat mud joint. The short edges of drywall sheets are not tapered; they meet at a butt joint.
Butt joints are more challenging to finish because they require that you build a slight, gradual mound to hide the joint. To make the mound subtle enough to go unnoticed, you must feather the joint compound over a wide area.
The same fiberglass mesh tape and similar techniques for applying mud are used for butt joints and tapered edges.
Apply the second coat of compound to the vertical butt seam after you've completed the second coat on the horizontal tapered seams, as shown in Step 2. That way, you'll do a better job of blending the intersection.
To minimize the difficulties of concealing butt joints, consider using a back blocking technique when hanging the drywall.