Joint ridging, also called beading, is a uniform, fine line deformation occurring at gypsum board joints. It is usually caused by compression of the edges or ends of the finished and decorated gypsum board resulting from the edges or ends being forced together from exposure to alternating periods of high and low temperature and humidity extremes due to thermal or hygrometric expansion. In order to permit the gypsum board system to stabilize, it is recommended that repairs not begin until the affected building has gone through at least one complete heating/cooling cycle. Repairs should only be undertaken in a warm, dry environment. Lightly sand the ridge down taking care not to damage the embedded joint reinforcing tape. Fill the surface over the joint with topping or all purpose compound, feathering as wide asnecessary to create an essentially flat surface. Allow compound to dry for at least 24 hoursbefore proceeding. After the compound is dry, it may be lightly sanded to feather the edges andremove any remaining trowel marks. Examine the sanded joint to etermine whether or not theridge has been eliminated. If the examination indicates that the ridge has not been adequatelyconcealed, additional feathering coats of joint compound may be required. Allow each coat ofjoint compound to dry at least 24 hours before sanding. The repaired joint should be painted with a coat of drywall primer and allowed to dry thoroughly prior to the application of final decoration.