Fire Management in a Coal Forge

by Albin Drzewianowski

OK, we have built our coal forge and now we are ready to light off the first fire.

Fire Tools: You will need certain tools to manage the fire.

• Forge Poker: - The poker should have a blade to allow you to push and pull coal onto the fire. I use two: one is the one we teach in the Blacksmithing-101 class and has a pointed blade with a goose neck; The other has the end of the poker flattened into a blade or spatula shape and just has a gentle curve to it. It is this 2nd one that I find most useful.
• Spike poker: - It is handy to have another poker which is just a long tapered rod, so that you can poke down to the bottom of the fire pot and open up where the air comes into the fire without really disturbing the fire very much.
• Drip Can: - A soup can on the end of a handle for watering the fire. (Be very very careful in watering the fire, it is very easy to crack your cast iron forge or fire pot.) Use the drip can to gently water down the outside edges of the fire to keep it from getting to large. You don't want to drown the fire.
• Coal Shovel: - Get (or make) a good sturdy one. Many of the small fireplace/firestove shovels that are sold are fine for removing ash from the fireplace, but do not stand up to use around the forge. You may have noticed that some of the shovels in the School have been bent and otherwise mutilated, those are the ones I am referring to.
• Pick-up Tongs: - A very light duty pair of tongs with long reins and very long thin bits. I consider these as part of my forge tool set. (They are not used to hold steel while hammering.) Use them to pick out pieces of clinker, adjust coke to critical locations, and most importantly, to fish out that small piece of steel that has slipped down toward the bottom of the fire pot.

First Fire:

Since this is the very first fire, let's assume that all you have is fresh coal, also known as green coal. Start a small fire with newspapers and kindling. Once the kindling catches, slowly increase the air supply. Next slowly add the green coal to the outside edges of the fire. Gradually work the coal in. If you take your time, you will not create a terrible amount of coal smoke. You always want to have flame coming out of the fire. The flame consumes/burns the smoke and you will have less smoke. This first fire is going to take a good 30-45 minutes to get to the point where you can forge. You want to end up with about a 3-4 inch high mound of coke in the center with a supply of green coal around the perimeter. In your fire, the green coal will be converted into coke - a clean burning carbon fuel. In the coking process, the volatile impurities go up in the smoke, the tars and oils present in the will burn off and you will be left with the coke.

Subsequent Fires:

For future fires you take the coke left from the previous fire and use that to start your next fire. I have found that it is worth the time to sift the remains from the previous fires to remove the ash. Also, pick out any clinker you see. I don't sift, each time I start a fire, but about every 2nd or 3rd time. For sifting, I took a small bucket and cut out the bottom and replaced with 3/8" hardware cloth. That size seems to work well. If the hardware cloth is too large, good coke falls through. Start your fire using the coke like you did your first fire. With a supply of coke, you can get the fire going just using newspaper. Most beginners have problems starting a fire with newspapers, because they don't use enough. I like to roll up the newspapers into a tight tube and then tie into a knot. I usually use at least 4-5 knots. Again, get the newspapers lit off, start the air, very gentle, slowly add the coke on top of the burning newspapers. Slowly increase the air supply as the fire gets going. Once you start to see the coke glowing orange add green coal around the outer perimeter and slowly work it in.

Managing the Fire While Working:

At all times you want to have a mound of burning coke to stick your steel into. As a general rule you should be able to stick you piece of steel into the fire horizontally and have a good 2-3 inches of coke above the steel. You will never get to forging temperature if you just lay the steel on top of the fire. Always add fresh coal to the outside and let it work its way toward the center. If you simply dump the green coal on top of the fire you will immediately generate a great deal of smoke. On my forge, I like to pile the green coal at the back of the fire, because it is easier to pull the coal to the edges, than to try and push it in place. You should be touching your fire tools every 2 to 3 heats: rebuilding the mound pulling green coal in from the edges. I like to use my spatula shaped forge poker to push down the inside edges of the fire pot and that helps to heap up the coke and add green coal to the bottom sides of the firepot. The coal shovel is also useful in pulling the coke up into a mound. A common mistake for beginners is to let the fire burn into a depressed hollow. Your steel will never get hot under those circumstances.

Putting out the Fire:

When done forging, I take my forge shovel and shovel the burning coals out of the firepot onto the tabletop of the forge (my forge table is large enough to allow me to do this), right next to the firepot. Then, using the drip can, I carefully water down the burning coals, making sure that no water falls onto the cast iron of the firepot. In the past I have seen references that letting the fire go out in the firepot leads to extra wear and tear on the firepot due to the acidity of the coal. This is especially true if you water down the coals in the firepot to help put out the fire. Make sure the embers from the fire are completely out before leaving the smithy.

-- RebStaup - 25 Jan 2008