Apply the end of a roll of painter’s tape to the bottom corner of the archway where the wall meets the edge of the archway frame. The edge of the tape should be flush with the frame. The wall next to the frame shouldn’t be visible and no part of the archway should be covered by the tape.
Press the tape against the wall with your fingers.
Extend the tape no more than 3 feet up the wall. It is easier to work in small sections. Press the tape against the wall with your fingers.
Continue applying the tape up the wall next to the archway until you reach the top corner where the archway begins to curve.
Press and hold your fingers against the tape. Follow the curve of the arch and extend the tape up the wall. Slide your fingers on the wall along the edge of the archway to keep the seam tight.
Continue applying tape on the wall above the curve of the archway until you cover the entire top edge.
Extend the tape down the wall on the opposite side of the archway in segments no more than 3 feet long. Press the tape firmly against the wall along the entire perimeter.
Cut the tape with scissors when you reach the bottom corner.