Spray the area surrounding the tear in the leather or vinyl surface with household cleaner (vinyl) or leather cleaner (leather). Wipe the area clean with a soft cloth, using slow, circular motions to avoid worsening the tear . Repeat this procedure, first using only distilled alcohol on the edge of a soft cloth to wipe the area surrounding the tear.
Cut a rectangular outline through the edges of the tear, using the blade of a utility knife and a straightedge. Manually peel off the cut pieces of vinyl or leather . Dispose of these cut pieces in the trash. Measure the dimensions of the outline with a tape measure.
Apply the leather-based adhesive from the leather and vinyl plastic repair kit along the inside of the leather tear. Heat the adhesive with a hair dryer, setting on "High" for a minute to turn the adhesive tacky. If you are repairing a vinyl tear, ignore these steps.
Cut a patch -- vinyl or leather -- taken from the kit, using the dimensions of the outline. Use a straightedge and a utility knife to do this.
Apply the adhesive to one side of the patch. Line up the patch over the tear. Place the patch down on the tear. Press the patch against the tear.
Hold the patch down for two minutes so the adhesive can take hold. Place a heavy object such as a clothes iron on the patch to keep it pressed against the tear. Leave the heavy object on the patch for the amount of time specified in the adhesive's instructions to let the adhesive set. Remove the heavy object once this time has expired.