I’ve tried a lot of methods to start a fire, my favoured is simply a sheet of news paper and charcoal. They produce a clean fire quickly. Everything should be self explanatory, except perhaps F: drier lint is useful, but smelly if you happen to have a hairy family =P: A wind and sun screen is useful when the fire is in it’s infancy.
Here you can see a close up of coal, coke, and charcoal respectively.
N: When using an electric blower controlling the air flow can be done in many ways. I use a shop vac directed to a T fitting. On the side of the fitting, opposite from the opening and going toward the forge, I’ve fitted a ball valve to allow excess air to be channelled to a side draft style hood/chimney.
O: Additional air can be vented from the ash dump as well by sliding it open a bit.
Before a new day’s hearth can be lit: sifting the ashes must be done, removing occasional bits of clinker. I toss the coke into one bucket and more questionable sifted shovels go into a bucket of water. The coke floats, and the ash clinker and coal sinks.
First a ring of coke is made at the bottom of the firepot. Some charcoal is present.
A little more charcoal is added. Charcoal or dried wood tender will ignite much easier than coke. If wood is used do so sparingly. I don’t know that you can’t weld in a fire with burning wood, but I do know it takes up hearth space and doesn’t burn as hot as the coked coal will.
A single sheet of newspaper is lit and placed in the center of the hearth. Many people will use lots of paper or ball up coke/coal fines into the paper. I’ve tried many methods; this is what works for me. Although a separate wood fire is always nice to steal burning coals from.
Some larger chunks of charcoal are quickly added while the air supply is on very low. I would use less kindling, just enough to catch fire before the paper burns out. The kindling or charcoal only need to burn long enough for the coke to catch.
The key at this point is not suffocating the fire. The blower is still on but you may find too much air causes smouldering kindling that won’t catch. Once again charcoal or even charred wood is much more forgiving. This bamboo charcoal burns hot but quickly. I use it to supplement my coal more than primary forging, so I added more than necessary.
Some coked coal is added.
When you are sure the coke has caught pile more on. The blower is blowing lightly. If you used kindling you can even carefully pull out the burning wood and seal it in an airtight container, or extinguish it some other way. This will make for an easier fire next time.
Remember that floating coke, now is a perfect time to layer it on. This will buy the coal a little time to cook. You may increase the air some, but you don’t need a lot of air yet. Just enough to keep things going.
Pile your wet coal around the center of the hearth/firepot. I snapped this picture right after the wet coke lit, just before cutting the blower off.
A handful of mostly uncoked coal (from the bottom of the water bucket) was then placed on top. Then a small scoop of wet coal was added. (This picture didn’t turn out well and I failed to notice at the time.)
The coal has heated up around the hearth and begun to melt and stick together as it’s coking. You can make a small entrance with your rake. Within this cave you’ll be able to keep an eye on your steel and see the color of it while still surrounding it with heat from almost every direction. The fire pot is 3 inches deep and the mound is about 5-6 inches above the forge table. Note – the fire is about at welding temperature.
This is the fire after welding. You can see it’s beginning to burn hollow– there isn’t enough burning coke inside the cave. While enough fuel is present inside this cave to work, use less air and water to allow coking to catch up. A hollow fire is a result of not enough coal coking because you’re keeping it too wet, or too much air being introduced. Too much air and not enough burning coke will cool your fire and create scale.
I use a ladle that’s easily held with my tongs to avoid steam. I can’t tell you when exactly you need to sprinkle the fire and surrounding coal with water, but the idea is to keep the fire from migrating out of the firepot (generally whenever you see large sooty flames). If the perimeter of the firepot becomes well coked it may need to be watered until it’s time to be slid inwards. Occasionally, after the blower is stopped, the coking coal atop the fire will ignite and go out as soon as the blower is cut on again. That is often a good sign to add more coal. I believe it also means the burning coke just below the top of the mound is consuming excess atmosphere from around the fire. This post is about building and maintaining a coal fire. Forging completely with coke is an entirely different animal. Heat cokes coal. Coal will burn, and it’ll stay aflame simply from atmospheric air. Coke needs more air introduced or blown towards it to stay lit. I know of no reason to burn coal other than to create a supply of coke and help maintain the shape of certain types of fire.
It’s time to sprinkle some water on the fire.
Time to add more fuel.
If heat becomes a problem then clinker build up could be the source. Clinker can be prevented from blocking the air orifice by firepot design, installed clinker breakers or simply by pulling it all out in one large sticky clump with your fire rake. To the left you can see clinker and flux from lots of welding. The middle and right are two different types of clinker from seperate coal sources.
I’ve found this sort of fire useful to heat several inches of steel. In this particular fire I forge welded a small hook out of 6 inches of half-inch square. Then finished working out the edge of a knife with a seven-inch blade.
I use many different types of fires and I am by no means an expert. Working odd bends and unusual shape or sizes without destroying a coal fire is difficult for me. It’s easier when extra coked coal is on hand, but coke still has to be raked back or added. Time must be spent waiting for the fire to get back up to temperature once burning coke is displaced. Proper fire management is one of the most basic skills anyone wanting to learn blacksmithing should know. I’ve had to teach myself most of these skills but I’ve by no means done it without the advice of others. I’ve not seen a good step-by-step pictorial on the subject so hopefully some may find this helpful. I plan to post a similar post over at Iforgeiron.com. It has been asked about an awful lot lately and I know many people like me are unable to attend classes. Around here, even at the events I’ve been able to attend, gas forges have been prominent or coal fires were started early and maintained irregularly and without discussion.