Silicon sealant is used as a traditional jointing method for cast iron gutters. The sealant should be spread evenly within the gutter socket, applying additional sealant around the jointing hole. Place the gutter spigot into the socket and compress both sections using an M6 x 25 corrosion resistant mushroom headed bolt, ensuring that the bolt head is on the inside of the gutter.The washer and nut should be lightly tightened from the underside of the gutter to allow excess sealant to be removed. Take care not to overtighten bolts as this could damage the gutter.