Coal and it's smoke

[Black Maple Forge]

My coal is very smokey at first (it doesn't get too much better), but cokes well and gets to welding heat in around 10-20 minutes (depending on air blast).

This leads to my question. What does it say about your coal if it has black smoke coming from it's flames? Can it burn as clean as charcoal, or is the smoke supposed to be there?

[keykeeper]

The coal I burn will smoke black sometimes, but mostly that cool yellow/green smoke when the volatiles are burning off. That is usually from well soaked coal.

Sometimes when I'm tending the fire, I'll knock a little too much dry green coal into the heart of the fire by accident, I'll get some really black smoke from the tar burning out (Looks like tar when its burning anyway), but that usually clears up quickly.

Once I have a nice fire with plenty of coked up coal, I get next to no smoke at all.

[Glenn]

The smoke from soft coal is the volitals being burned off while the coal is making coke. To get rid of most of the smoke, punch a hole in the top of the coal to form a volcano and ignite the smoke. See the second photo.

The black smoke from the fire usually means you try to burn the coal too fast. Use more coal and build a bigger fire, let it form a fireball of coals.

You can use coal with little smoke but it takes maintaining the fire to burn at optimum combustion.

[UnicornForge]

You can reduce the smoke by adding coal on the sides of the fire, and gradually moving the coal inwards so that it burns off the volatiles and cokes as it moves inwards. Massive amounts of smoke result by not properly maintaining the fire, letting the fire burn uncontrolled and then dumping green coal into the center of the fire.

[keykeeper]

Exactly what I was trying to say, Glenn. Hmmm...those photos look vaguely familiar to me...he he

[UnicornForge]

I would be really nice if someone was to post the ultimate detailed explanation, with photos, of how to properly manage a coal fire so that smoke is minimized. I am pretty sure that my brief explanation is not sufficient.

For years I knew the theory, but it all did not come together until I was working a coal fire at a Damascus/paternwelding knifemaking course, and I started maintaining a proper fire by moving the coke walls inwards as the center burned out, moved the coal inwards from the sides, added new coal only at the outer edges, and used water to control the burn outside the forge welding area. To survive the course this was the only way to keep the fire at forge-welding quality and temperature all day. On one hand I felt stupid for doing it the wrong way for so long, on the other hand I was glad that I finally understood how to maintain a forge-welding fire that allowed me to do in about an hour that would have, in the past, taken me days to accomplish with a coal fire.

[Black Maple Forge]

Thanks for the help! I'll try the coal again later and see how it goes!

[Glenn]

Unicorn, the short and simple

Build a fire from sticks, pine cones, newspaper etc and add coal slowly. The better the fire from sticks etc the more heat it produces. When you start adding coal a little at a time, it will catch easier and the fire will burn most of the smoke. Add more and more coal as the fire catches. The sticks will burn out and the coal/coke forms a fire ball. Add more coal keeping a hole in the top for the flame to escape and burn the smoke. Poke the fire down so there is no hollow space as the fuel burns out. Add more coal and build the fire ball to the size you need to heat the metal you are using.

Now comes the maintenance part. Add about a generous amount of coal to the circumference of the fire, or close to the fire on the forge table. As the fire ball consumes the fuel, the coal next to the fire ball is transformed to coke. This transformation drives the volitals from the coal (smoke) and the fire burns the smoke. The reason for the fire always being able to get through the coal much like a volcano is to ignite and burn the smoke.

As the fire ball burns, you drag coke into the fire to replace the fuel burned. You then drag coal into the fire to be transformed into coke. Then you need to shovel more coal on to the circumference of the fire to have a supply to draw from as needed. Think of it as an assembly line in progress, all moving closer and closer to the fire ball. With a little practice you can maintain a constant size and heat in the fire ball.



The fireball, coke, and coal should form a mound above the fire pot. The sweet spot is about 1/2 to 2/3 up from the bottom of the fire ball.

[ThomasPowers]

Unfortunately the "ultimate description" would probably be longer than the Encyclopedia Britannica as each forge and each type of coal and each type of fire needs different handling to get the best from it.

The fires I used in OH using sewal seam nut coal are quite different from the Colorado coal fines I get out here. Both can work but you have to learn different methods to get the best from them.

[rmcpb]

Once started my fire is virtually smoke free, unless I get carried away and put some green coal on the fire. The most smoke is generated when starting the fire. To help prevent this I always have a coke up at the end of each session so I have a lot of coked coal to start the fire with next time. Then its a matter of getting a bright wood fire going then adding the coked coal around it in a volcano shape and away it goes.

I have found that you can never have too much coked coal on hand and often use it as a exercise for the boys even if we are not forging. They light the fire, get it going , have a play then coke for all they are worth.