What is the primary purpose of joint compound when used with joint tape?

The primary purpose of joint compound used in conjunction with joint tape is to conceal the joints between drywall panels. When drywall is installed, the panels are typically not perfectly aligned, and there are seams where they meet. Applying joint compound over these seams, along with joint tape, smooths over these connections and creates a seamless appearance. This process is essential for achieving a smooth, even surface that can be painted or finished without showing any visible lines or imperfections from the panel joints.

The joint compound serves as a filler, while the joint tape provides reinforcement to prevent cracks and ensure a durable bond as the compound dries and hardens. This combination is fundamental in drywall finishing, as it helps create a polished look for interior walls.