TO FORGE.--Gently warm the steel to remove any chill is particularly desirable in the winter. Then heat slowly and carefully to a scaling heat, that is a lemon heat (1,800 deg.-2,000 deg.F.), and forge uniformly. Reheat the tool for further forging directly the steel begins to stiffen under the hammer. Under no circumstances forge the steel when the temperature falls below a dark lemon to an orange color: about 1,700 deg.F. Reheat as often as is necessary to finish forging the tool to shape. Allow the tool to cool after forging by burying the tool in dry ashes or lime. Do not place on the damp ground or in a draught of air. The heating for forging should be done preferably in a pipe or muffle furnace, but if this is not convenient use a good clean fire with plenty of fuel between the blast pipe and the tool. Never allow the tool to soak after the desired forging heat has been reached. Do not heat the tool further back than is necessary to shape the tool, but give the tool sufficient heat. See that the back of the tool is flatly dressed to provide proper support under the nose of the tool. HARDENING.--Slowly reheat the cutting edge of the tool to a cherry red, 1,400 deg.F., then force the blast so as to raise the temperature quickly to a full white heat, 2,200 deg.-2,250 deg.F., that is, until the tool starts to sweat at the cutting face. Cool the point of the tool in a dry air blast or preferably in oil; further cool in oil, keeping the tool moving until the tool has become black hot. To remove hardening strains reheat the tool to from 500 deg. to 1,100 deg.F. Cool in oil or atmosphere. This second heat treatment adds to the toughness of the tool and therefore to its life. GRINDING.--Grind tools to remove all scale. Use a quick cutting, dry, abrasive wheel. If using a wet wheel, be sure to use plenty of water. Do not under any circumstances force the tool against the wheel so as to draw the color, as this is likely to set up checks on the surface of the tool to its detriment. The Firth-Sterling Steel Company say: INSTEAD OF PRINTING ANY RULES ON THE HARDENING AND TEMPERING OF FIRTH-STERLING STEELS WE WISH TO SAY TO OUR CUSTOMERS: TRUST THE STEEL TO THE SKILL AND THE JUDGEMENT OF YOUR TOOLSMITH AND TOOL TEMPERER. The steel workers of today know by personal experience and by inheritance all the standard rules and theories on forging, hardening and tempering of all fine tool steels. They know the importance of slow, uniform heating, and the danger of overheating some steels, and underheating others. The tempering of tools and dies is a science taught by heat, muscle and brains. The tool temperer is the man to hold responsible for results. The tempering of tools has been his life work. He may find suggestions on the following pages interesting, but we are always ready to trust the treatment of our steels to the experienced man at the fire. HEAT TREATMENT OF LATHE, PLANER AND SIMILAR TOOLS