Finishing out drywall, also known as taping, involves applying multiple coats of wet joint compound over the seams. Each application must dry completely before you apply subsequent coats. Some types of joint compound dry more quickly than others do, but they require special care when applying. All-purpose joint compound, frequently used for each application, dries in a couple of hours on a hot day, but in cool, humid weather, it can take days to dry.
Raise the Temperature
Turn on the furnace, if possible. If not, put space heaters in the just-taped room to raise the temperature. In the same way a clothes dryer dries a load more quickly on "Hot" than on "Cool," so does warm air speed up the drying time for joint compound.
Move the Air
Open a window to let in a breeze and to let out the high humidity level in the taped room. As the joint compound dries, the moisture in it gradually evaporates, raising the humidity level in the room. When the air in the room is humid, drying takes longer. In addition to opening a window, put a fan in the room to circulate the air.
The first coat of joint compound is the thickest, because you have to use enough mud to fill the joints and cover the screw dimples. This coat takes the longest to dry. Make each subsequent coat, however, very thin. Not only do thin coats dry more quickly, they reduce the risk of indentations and future cracking. As joint compound dries, it shrinks. Multiple thin coats offer a smoother surface.
Use Hot Mud
Fast-drying joint compound, called "hot mud" by the pros, dries very quickly, but take precautions to keep it from drying before you finish applying it. When using hot mud, mix up only enough to fill your mud pan once. When you've used that up, wash the mud pan and your trowel before mixing more compound. A little bit of residual dried compound can act as a catalyst to set a new batch of compound within minutes.