Proceed to heat the oven as follows: Free the grate of ashes and clinkers, then put the wood (which should be thoroughly dry) in the furnace; then put some paper in the furnace and light it; then open the damper and the draft door. When using coal for fuel, put some dry wood in the furnace, then put coal on it and light it, then draw the damper and open the bottom draft door. Now watch your fire, adding fresh fuel. When about one-third of the fuel is burned, fill the furnace with as much fuel as it will hold, then close the door; continue this process about three times. When the last furnace of fuel has burned down about one-half, close the damper partly (to prevent the heat from escaping through the open flue) and as the fire continues to burn down, continue closing the damper, and when the fire has burned down completely, close the damper entirely and shut the bottom draft door. The oven should be fired at least one hour before you begin baking in it, to allow the heat to moderate and to become evenly distributed throughout the oven, producing what is known to the trade as a ground heat. If you bake in a freshly heated oven your goods will scorch on the outside and remain doughy inside. Some goods require a very quick oven, but the first heat in a fresh oven (providing the oven has been properly heated) is almost too hot for any class of goods. If you are compelled to bake in a freshly heated oven, open the damper and allow the oven door to remain open while baking, thus allowing a portion of the excessive heat to pass into the flue. This first heat is called flash heat, because it is not a lasting heat. An oven may be overheated or underheated to a degree as to render it unfit for service. Bakers should be very careful about heating their ovens. Little fuel can be used and excellent results obtained, providing the one who does the firing knows how to fire an oven. Follow our directions very carefully when firing ovens. If you have too much heat in your oven you can remedy that by drawing the dampers and leaving the oven door open. But if you have an underheated oven you will find that the only remedy is to build more fire. This is wasteful extravagance, though sometimes it is difficult to avoid, especially when you have damp or green wood. There is also a flash heat in an underheated oven, but it is not intense, nor does it last very long.

On the other hand, if the bottom draft and furnace doors are not air tight, though you have them closed and have the dampers open, and only a moderate breeze is blowing, the fire will burn briskly. If you want the fire to die, close the damper and the bottom draft door. When you close the damper and the bottom draft door you shut off the supply completely, or the life of fire, then it dies. Chimneys should be built to tower above the roofs of adjoining buildings, so that the air currents can pass over them unobstructed.

We have shown above that it is necessary to supply fire with air to create combustion, so we will now show what is understood by combustion.

Combustion is defined: “To burn, or burning. The process by which bodies combine with oxygen and are thus seemingly destroyed. Oxygen exists uncombined in the atmosphere to the extent of 22 per cent. by volume and more than 23 per cent. by weight.” The fact that air (and plenty of it) is absolutely necessary to produce combustion, seems foreign to most people who fire ovens, etc. These people poke a fire and give it draft as a matter of fact, but do not know why. All highly flammable material, such as pitch tar, resin, pine wood, paper, coal oil, gasolene, etc., and even gas will not burn unless mixed with a certain per cent. of air or oxygen, and all so-called inflammable (fire proof) material, such as mineral wood, prepared felt, asbestos, iron, steel, etc., can be entirely consumed by fire if subject to sufficient blast. Under ordinary conditions, so-called fire-proof material will not burn, but throw them into a blast furnace—one equipped with a powerful blower—and watch the results. In a short space of time you will find nothing left to indicate that such material had been thrown into the furnace.

The above illustration is given simply to show what a necessary factor air is to produce combustion even in a limited degree. Not only is air necessary to produce combustion, but the more air or draft you give a fire the more perfect the combustion, and the more perfect the combustion, the greater the heat it produces, and the greater the heat produced, the less fuel is required. Air is less expensive than either wood or coal; bear this in mind and profit by it. You have learned the necessity of using the poker frequently, and you have learned what is meant by draft and combustion. Now be guided by what you have learned.

It is not necessary to go into detail about the construction of continuous baking ovens, nor of the firing of these ovens. The builders of such ovens will furnish you the necessary information when you get ready to purchase such an oven. Enough is said when we say that more fuel is required to heat a continuous baking oven than furnace ovens, because the fire does not get inside of the oven proper (the baking chamber), but encircles it. The heat must pass through the brick before it enters the baking chamber. For this reason more fuel is required to heat the oven. But after you have the required temperature in your oven, and begin to bake in it, but little fuel is required to keep it at the regular temperature during the baking period.

Proceed to fire continuous baking ovens same as you would furnace ovens, and when you have the temperature in the oven as required, close the damper partly and the bottom draft entirely, and put on fuel only when necessary, that is when the temperature begins to fall during the baking period. When the temperature begins to fall, open the bottom draft and also the damper and poke the fire frequently. It is not absolutely necessary to keep up the fire after your oven has the required temperature, unless your work requires it. In large bake shops where large batches of bread are baked continuously, it is absolutely necessary to keep up the fire, but in small shops this is not necessary unless a larger variety of goods are made; in that case it would be best to keep up a low fire.

Preparing Ovens for the Baking Process.

This applies to furnace ovens only, because the fire enters the baking chamber. The flames as they circulate around the oven carry with them more or less ashes, and scatter them over the hearth. This necessitates cleaning the oven before it can be used, especially when baking bread on the hearth. A mop or “swab” is used for this purpose. This mop or “swab” consists of a long pole, on the end of which a cloth or gunny sack is fastened. An old peel handle may be used for this purpose or you can purchase a swab pole from any supply house. Proceed to swab the oven as follows: Dip the cloth into a vessel of clean water and get it thoroughly wet, then put it into the oven and push it back as far as possible and let the pole rest on the hearth, then take hold of the pole with both hands and bear down on it so as to raise the cloth slightly to allow it to whirl around freely, then draw it out about 1½ feet with a rotary motion; then push it back again; do this quickly. By pushing the pole forward and drawing it back with the rotary motion, you cause the cloth to whirl around and throw the ashes or dust forward towards the oven door. Continue this process, beginning at the back of the oven and working forward to the oven door, then take out the swab and put it on the rack; then take a broom and sweep out the dust or ashes.

While swabbing the oven you raise considerable dust, therefore it is necessary that the damper should be open to allow the dust to pass into the flue. Usually while swabbing the oven the atmosphere in the oven is thick with dust and if the damper were closed this dust would settle on the hearth; but by keeping the damper open during this period most of the dust is drawn into the flue. When the atmosphere in the oven is clear (free from dust), close the damper and the oven door. Your oven is now ready for the baking process, but I would advise you not to bake in the oven immediately after it has been heated, unless it is absolutely necessary, because the first heat in an oven is usually intense.