Best Fuel for a Blacksmith Forge

Learn the difference between wood-burning forges and coal-burning forges to figure out which will be your best bet for blacksmithing.

  • Wood-fired forges burn cleaner than forges that require coal.
    Photo by Whitlox Homestead

I want to start blacksmithing. What’s the difference between wood-burning forges and coal-burning forges? And can you really get a wood-fired forge hot enough to blacksmith?

We’re hobbyists, but we own both wood-burning and coal-burning blacksmith forges on our homestead. We started by building a coal-burning forge out of a brake drum to begin blacksmithing, and we now use a commercially built wood-burning forge. We say “commercially built,” but really it’s handmade by a small homeschooling, farming family in Oregon called Whitlox Homestead. Personally, we enjoy using the wood-burning forge much more for a number of reasons, although coal has benefits as well.

Coal and propane are the most typical fuels used in blacksmith forges. On the East Coast, coal is readily available and therefore more affordable than on the West Coast. Coal burns more efficiently and hotter than wood. Because of its efficiency, the volume of coal needed is substantially less, too. In an hour, you’ll burn through approximately a cantaloupe-sized piece of coal versus a 5-gallon bucket of wood scraps.

When coal is burned, tars, oils, and gases burn off, and what remains is pure carbon — called “coal” or “coke.” Unfortunately, when we burn coal, we breathe in acrid smoke, our faces and clothes are blackened, and we enjoy the experience less than when we use clean-burning wood. Obviously, we could mitigate some of these negatives with proper air ventilation, but, as hobbyists, we couldn’t justify the investment of time and money.

In contrast, when we burn wood, it results in wood charcoal and continues to burn until it turns to ash. It’s the wood charcoal that supplies the intense heat needed to weld. Wood tends to burn cleaner and results in wood ash, which, unlike coal ash, has beneficial uses in the garden and orchard. Wood also comes from a renewable resource that we have on our property, and it’s inexpensive to obtain — we always have an abundance of wood scraps that are perfect for our blacksmith forge. It’s best to use dry wood that hasn’t been treated. Softwoods become charcoal quicker than hardwoods do, and they produce less ash. Remember, the smaller the piece of wood, the faster it will become charcoal, and the more heat it will produce. Too small, though, and you’ll need to reload wood more frequently. Try to use fairly uniform pieces that are about 3 inches on each side or use sticks that are about 2 by 6 inches.

Our wood-burning forge has a V-shape that forces the charcoal and heat to one area, which saves us from having to pull more fuel into the center of the forge, as we’d have to do with a coal-burning forge. This saves time and effort and produces a more even heat. This easy method of fire management keeps the fire from spreading, which produces the concentrated heat that’s needed to blacksmith. A concentrated fire makes airflow easier to regulate. Remember that more air can get a fire going, but it can also put it out or produce cool spots.

9/23/2021 4:27:52 AM

Actually having leftover coke is completely normal and a natural product of a forge fire that has been snuffed at the end of working. Coke is often removed and set aside as desirable "pre-cleaned" fuel for forge welding sessions. You can actually buy coke outright but it is a little more expensive per pound than raw coal. Also, clean or not a raw coal fire will always smell like burning petroleum due to the tars burning out of the coal as it becomes coke. I actually started blacksmithing on the farm with a wood forge ~40 years ago, mostly shaping horseshoes but occasionally other things. These days I prefer gas forges, I have close neighbors who are tolerant of hammer noise; I don't want to add smoke to the mix. Oh last thing where wood and gas have an advantage: no clinkers, the little balls of fused silica glass from impurities in the coal that eventually have to be chipped out after they start clogging up your tuyere...

9/22/2021 8:37:19 PM

From all I have read about blacksmithing if you are left with coke in your coal forge then you are doing something wrong. The coke is what actually produces the hot fire needed tor metal work. The coal around the fire turns to coke as it is moved towards the heat and then burns as it is moved into the fire leaving ash and cinders. A proper fire will produce little smoke although some is unavoidable..

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