An improved method and apparatus for by-product coke oven operation wherein the problems of pollution caused by gases leaking through coke oven doors during the coking cycle are eliminated by providing a door having a passage for the injection of a special material to serve as a positive seal between the door and the jamb of the oven to plug the crevices through which gases escape. The material injected possesses fludized properties during injection in order to fill the space between the door and jamb and upon the baking thereof it solidifies and hardens with a glazed-like surface in order to make possible the removal of this material after the completion of the coking cycle without the necessity of cleaning the door and jamb. In preventing gases from escaping the coke oven the pollution problem is eliminated and the following advantages ensue: A. No fires occur at the doors, the outside framework is thus protected. B. No air is infilterated into the oven thereby minimizing carbon deposits. C. The oven walls near the doors remain warmer during the coking cycle. D. The brick work near the oven doors is not subjected to excessive cooling thereby minimizing maintenance on oven ends. E. Warpage of door jambs on high ovens is minimized. The improved method and apparatus is adaptable to existing facilities without difficulty and without stopping productivity.