I'm going to show you how I replaced a cast Iron closet flange using lead wool and oakum. The Lead wool gets packed into the joint rather ten melting and pouring it in. Much safer this way. " Use protective Gloves when handling The Lead wool." This particular flange was about 1" below the finished floor and required at least 3 wax seals to set the toilet. I'm going to raise the flange flush to the finished floor. Normally the top end of the cast iron closet bend would also be flush with the floor. A standard cast iron flange has only 2" of depth. For this job I used an extended hub Flange. There are other methods of installing a new flange onto a cast Iron closet bend. There are products that use a neoprene seal and just bolt on but I have had my share of replacing those so called easy fixes. This is not an easy fix but it will not come loose if done right.