Abstract: A blade for cutting a groove in ductboard and forming a corresponding scrap strip of ductboard. The blade includes two blade portions depending from a support member such as a hand tool with a sled for engaging the ductboard. Each of the blade portions includes an inner end which engages the other inner end to partially fix the blades relative to each other and partially restrict the blades from spreading which may be caused by the horizontal grain of ductboard.

Abstract: A method and an apparatus are provided for removing halogenated polyphenyl materials from used or waste oil supplies. Waste or used lube stock is subjected to rerefining procedures in order to remove many of the impurities found in such waste or used stocks. The rerefined stock which is contaminated with halogenated polyphenyls is continuously pumped under pressure and mixed with highly pressurized hydrogen gas which is heated to a relatively low temperature and passed through a bed of catalyst in order to promote a reaction that forms a hydrogen halide and a polynuclear aromatic material that does not exhibit the environmental and health hazards of a halogenated polyphenyl material such as PCB's.