Coal Forge vs. Propane Forge

by Albin Drzewianowski

In order to blacksmith, you basically need 3 things: heat, anvil and hammer. Let's address how you are going to heat up your steel. Generally speaking, you have 2 options: coal or propane gas. The ideal blacksmith shop would have both. Each type of forge has positive and negative features.

I have to admit, I am biased toward the coal forge. Overall, I think it is more versatile. However, it has one really major negative feature - COAL SMOKE. Many blacksmiths, due to their circumstances, neighbors, etc, can not be generating coal smoke in their home forges. (We will discuss how to minimize coal smoke when we talk about fire management in a future installment.) Also, if you are forging inside, you must have a chimney. So if you are going to use coal, you need to deal with the smoke issue. When you situate your blacksmith shop, take into consideration, if possible, which way the prevailing winds blow. Will the smoke be blown toward your neighbor's house?? If you forge in your driveway or patio, which way will the smoke blow?? Remember, the smoke contains soot which can precipitate out down wind.

When you build your blacksmith shop, if you use a coal forge you will need a chimney. It should be, at a minimum, 10" round, 12" is better, or the equivalent if square or rectangular. In my opinion, 8" stovepipe just will not handle the amount of smoke generated when starting up the fire or when adding fresh coal to the fire. Some people add a blower to the chimney to help exhaust the smoke. Just remember, that coal smoke is quite corrosive and if you put a fan or blower inside the stove pipe, it probably won't last. You need to mount the blower out side the pipe and direct the output from the blower into the chimney to push or pull the smoke along. Having a good draft in the chimney is critical to successfully dealing with the smoke from your forge.

The positive features of a coal forge:

• You can fit pretty much any size piece of metal into the fire.
• You can get a localized heat.
• It is easier to forge weld (in my opinion).
• You have less scaling compared to a propane forge.
• Adds less heat to your shop in the summertime, as compared to a gas forge.

The negative features:

• If you are not careful, you can easily burn up your work.
• It is difficult to have multiple pieces in the fire at the same time, for example when making keychains, you want to have a half dozen or so in the fire at the same time.
• Tends to be dirty/sooty. You get more dirty and your shop is more dirty.
• Can be difficult to obtain good blacksmithing coal.
• Coal takes up more storage space.
• Takes longer to get the fire going.
• A little more of a fire danger since this is an open flame.

Pretty much all of the above applies to using commercial coke vs. coal. There are a few differences. With coke you still need a chimney, but the smoke is not objectionable, the way coal smoke is. You will need to have a steady flow of air into the fire, or the fire goes out. Forging with coke if you use a bellows or hand crank blower is problematic. Coke burns hotter, this can be both a positive and a negative feature. You need a heavier/thicker fire pot. Coke burns cleaner, preferable for forge welding. Commercial coke in a good size for blacksmithing is even more difficult to locate than good blacksmithing coal.

Now, looking at the propane forge. Positive features:

• The propane forge is more convenient.
• Don't need a chimney when used indoors.
• It fires up quickly and you can be ready to forge in as little as 5 minutes. *Can be set so that your work does not burn up.
• You can have a lot of blanks in the forge at the same time; very handy when making multiples of small items, like hooks or keychains.
• Propane is readily available pretty much everywhere.
• Adds more heat to the shop in the winter time.
• Overall cleaner.
• Don't need the storage space you would need for coal.
• More portable.

Negative features of a propane forge:

• Limited to the sized of the forge box, can be difficult to get large or assembled pieces into the Forge.
• Can't get a localized heat, generally the entire piece is heated up. Need to use tongs more than when working with coal.
• More difficult to weld.
• If used inside, there is a greater danger from carbon monoxide.
• The steel scales more. Some say that the scale from a propane forge is more difficult to get off than the scale from a coal forge.
• Adds more heat to the shop in the summer time.
• Unless you build it yourself, probably more expensive to purchase.

The positives and negatives of propane gas apply pretty much to natural gas with the following differences.

• Natural gas does not burn quite as hot as propane.
• You will need to run pipe from where the natural gas comes into your property to your blacksmithing area. Does not have the portability that propane as.
• Sometimes residential natural gas service is at too low a pressure.
• Some blacksmiths have had hassles with the local gas company over pressure and regulators.

Each blacksmith has to look at his/her own circumstances and weigh the pluses and minuses and determine what will work best.

-- RebStaup - 25 Jan 2008