There are two varieties of joint compound or mud available in the market - powdered and premixed. Between the two, premixed mud is preferred and recommended by many users. Mixing the compound is very crucial, and the consistency of it should neither be too stiff, nor too loose.Stiff cement will be tough to apply on the joints, whereas a loose mix cannot be scooped with a trowel. During the mixing process, do not whip it too much as it will catch air, causing bubbles to form when applied between the joints.