Gas vs Coal Forge -Which One Is Better for Blacksmithing?

Choosing the right forge is one of the most important decisions when it comes to blacksmithing. It is the heart of every workshop. A lot of people are interested in which type of forge is the best for their work. You may hear that most of the well-known metal masterpieces in the past are made in the coal forge, therefore it has to be better. Well, not necessarily. A lot of these sayings come from more of a traditional blacksmith.

On the other side, new generations are saying that gas forge is the best option. As always, truth is somewhere in the middle. There is no simple and clear answer when it comes to this topic, so in this article, we decided to cover the main differences between the two and also their pros and cons. Let’s settle this once and for all.

Gas Forge

Gas forge or propane forge, however, you want to call it, is becoming more and more popular nowadays, and for a very good reason. For everyone who is just getting started with blacksmithing, learning about forging, heat-treating, tempering, steel choice, etc. can be challenging. Adding to the fact that you should learn proper coal fire management is quite overwhelming for most beginners.

A gas forge (affiliate link) is extremely easy to use and light. All you have to do is turn on the burner, and gas tank and it is ready for work. This is yet another advantage over coal forge because, with coal-fueled forges, you have to wait quite a time to achieve the high enough temperatures required for forging.

A lot of people believe that propane forges cannot achieve welding temperatures, and people saying that include some experienced smiths. While this can be the case for the improperly installed forges, the ones which are properly installed can easily forge weld. Proper installation means that the burner is properly designed, the forge contains enough burners, the volume of the chamber is big enough, etc.

Should You Use Propane or Natural Gas for Blacksmithing?

The two most popular fuel choices are propane and natural gas. Propane has been shown to achieve higher temperatures than natural gas due to its energy content. Propane contains nearly twice as much energy as natural gas. One cubic foot of propane contains 2,516 BTUs while natural gas contains only 1,030 BTUs. As you can see, this is twice as much, and that makes a noticeable difference when it comes to forging.  

Keep in mind that using a gas forge in the summer can be challenging because it radiates a lot more heat than a coal forge. In the summer, we avoid using a gas forge as much as possible because working in such conditions is often unbearable.

Except for burning hotter, propane also burns less volume per hour than natural gas. So, in 1 hour 100,000 BTU propane forge burns around 40 cubic feet, while a natural gas forge burns 100 cubic feet in an hour. As you can see, it is a big difference.

In regards to safety measures, natural gas is lighter than propane, so it dissipates more quickly in the air than propane. However, this does not mean that you should not wear a respirator when working with natural gas. Both of them require the same safety measures.

Gas forges require proper ventilation as they can easily be sources of carbon monoxide poisoning. With proper ventilation, a carbon monoxide detector is also necessary as a safety precaution.

In terms of environmental issues, there are no significant differences between propane and natural gas as both of them are clean burning. Natural gas is considered a greenhouse gas but burns clean like propane. The reality is that there is little distinction in their environmental pollution as both are eco-friendly fuels.

Both are burning cleaner than any other fossil fuels because their harmful emissions like carbon dioxide, carbon monoxide, and nitrous oxides are much lower.

If you had to choose between propane and natural gas, we would recommend you choose propane. It achieves higher temperatures and burns less volume per hour.

Another thing to keep in mind, and probably one of the most important social factors for a lot of blacksmiths, is the friendly nature of gas forge with your family and neighbors. Unlike coal, gas does not produce smoke. Now imagine a nice, warm Sunday morning. You and your family are chilling in your backyard. All of sudden, acrid coal smoke is drifting in through your open windows. You know exactly where it comes from. It is your neighbor’s blacksmith and his coal forge. With coal, all your neighbors will be alarmed about your work.

With gas forge, there is no such problem. In fact, nobody would even know what you are doing. This, of course, is not an issue unless you are living outside the city where nobody is around you, so whenever there are neighbors around, we would suggest using a gas forge.

As far as availability is concerned, gas is easily available compared to coal. You can get propane at a lot of places, including local hardware stores, larger grocery stores, big-box homes, etc. In contrast, blacksmithing coal is getting harder and harder to find because of numerous mine closings due to Federal regulation.

As more and more new smiths are starting to use gas, I believe that in the near future, gas will entirely replace coal as a blacksmithing fuel due to economical and practical reasons.

Is It Better to Replace or Refill Your Propane Tank?

Once you run out of gas, you can either refill or change the empty tank for a full one.

Refilling a Propane Tank

If you are more likely to rely on your own procedures like maintenance and checking the leaks rather than somebody else, refilling your gas tank is a better option for you. It is also noticeably cheaper than replacing it with a new one. You may also realize that you can get more propane when refilling by yourself because, in a lot of exchange vendors, it is a policy to not fill the tank entirely.

Keep in mind that your gas tank should be not older than 5 years as some refill stations may refuse to refill it. Because of that, it would be a good idea to recertify your gas tank to extend its lifespan.

Exchanging a Propane Tank

On the other hand, if you want a faster and more convenient option then exchanging a propane tank is a better solution. It is far easier to find an exchange station than a refill station. With this option, you are guaranteed that the tank is properly leak-tested, cleaned, and has printed safety information and guidance.

Before finalizing an exchange, you should pay attention to the weight of the tank. Namely, tanks can vary in their empty tare weight (TW). So you should always look for ones with the lowest tare weight. Another important factor is the condition of the tank. Make sure that a new tank is not corroded or expired.

If you are planning to use propane forge, we would recommend you get at least a 100lb tank which is 24 gallons of propane. With bigger tanks, you get more discounts. Ambient temperature is one more important determinant of propane. Just because propane is within the tank, it doesn’t mean it is unprotected. The optimal environmental temperature for propane is 60 degrees Fahrenheit (15°C).

With higher temperatures, the tank gauge reading goes up. The propane weight is still the same but its molecules have just become more spread out. The opposite happens when temperatures are lower. The volume of propane has decreased because of its greater density at lower temperatures. When working with gas forge, make sure to keep tank pressure up as the tank can stop working properly.

In order to maintain an ideal temperature, one of the best and most effective ways is to use Propane Tank Heater. It easily transfers heat to the tank, which in turn raises the BTU of the propane. It will also save you a lot of time from frequent tank refills. Although not necessary in the summertime, during winter it is definitely worth using.

To properly gauge the economy between coal and gas you should consider a lot more than just fuel cost. For example, with a gas forge, you can start working the moment you light off the forge whereas, with a coal forge, you spend a lot of time tending the fire. The cost of time is more precious than money. Also, with a gas forge, you can make a lot more pieces per hour, which makes your production work significantly effective compared to a coal forge.

How to Insulate a Gas Forge?

When building a propane forge, there are 3 main options in terms of inside insulation:

  • Hard Concrete Fire Bricks
  • Ceramic Fire Bricks
  • Kaowool

Hard Concrete Fire Bricks are good options up to 3000 degrees Fahrenheit (1648°C). They are difficult to cut, so you will have to use something like a grinder with a masonry cut-off wheel, otherwise, it won’t work. You can order them online or buy them at your local fireplace stores. The average price per piece is around $2.50, which makes it the cheapest insulating option. Concrete Fire Bricks don’t reflect heat back into the forge but rather they absorb it, so in terms of efficiency, this is the least efficient option.

Ceramic Fire Bricks are very soft and light. You can easily cut them with any woodworking tool. They are good up to 2600 degrees Fahrenheit (1426°C). You can mostly find them at your local pottery stores or buy them online. The average price per piece is around $6. They can achieve higher temperatures due to reflecting heat into the forge and using less fuel.

Kaowool is a soft ceramic blanket material that can be easily cut with a utility knife. It is good up to 2600 degrees Fahrenheit (1426°C). The texture of kaowool is very similar to fiberglass insulation. Coating of kaowool is necessary because heated kaowool releases its dust particles which can be extremely dangerous to your health. It is by far the most expensive insulating option. In order to achieve welding temperatures, it is recommended to use kaowol as an insulator due to its highest efficiency.

PROS of the Gas Forge

  • Quick and easy to light
  • Burns clean
  • Easy to operate
  • Excellent for production work
  • Easily available and simple to make
  • More suitable for beginners
  • Portable
  • Neighbor-friendly

CONS of the Gas Forge

  • Quite noisy
  • Versatility
  • Hard to get localized heat
  • Radiates a lot of heat in the room

Coal Forge

Without any doubt, you can say that coal is a historical blacksmithing fuel. All historical masterpieces made from metal have been made in coal. If you like blacksmithing because of its traditional aspects, like the mystique of burning coal and playing with the fire, you may want to use coal forge instead.

Compared to a gas forge, it is a lot harder to properly manage due to a lot of reasons. Different types of coal require different fire control and management. Lighting coal can sometimes be complicated, especially for a beginner blacksmith without much experience. This is also the reason why a lot of the blacksmithing classes teach fire management before anything else.

Today, good blacksmithing coal is getting more and more difficult to find. It is also more expensive than using gas as fuel. The biggest advantage of coal forge is its versatility. You can forge basically any items of all sizes, mostly without any limitations. With coal forge (affiliate link), you can also get good localized heat whereas with gas forge it is not possible. It is also much easier to achieve welding temperatures due to higher burning.

They also require much more attention to the fire, so you can only light the fire and leave. You have to constantly be close and add air as necessary.

There are a lot different types of coal, but 2 of them are mostly used in blacksmithing. These are anthracite coal and bituminous coal. Coals’ quality is determined by a lot of factors. Some of which are volatile matter, calorific value, carbon content, sulfur content, etc.

When working with any type of forge it is extremely important to keep safety precautions. When burning, some coal has a tendency to pop out from the fire so be sure to wear safety glasses. Especially when you stand near the forge.

For everyone just starting out in blacksmithing, we would recommend you get around 50lb of coal. Beginners typically spend more coal than experienced smiths because of improper fire management. Also, make sure to have a well-designed chimney and ventilation for proper and safe work. In case coal is not available for you, you can experiment with charcoal.

In terms of forge construction costs, coal is the clear winner. To build a simple and cheap coal forge, all you need is some red bricks, a pipe, and an old hairdryer.

To see how to make the simplest and cheapest coal forge, see The Easiest Way To Build a Blacksmithing Forge.

However, the amount of saved money realized in fuel costs makes the gas forge superior in the long term.

PROS of the Coal Forge

  • Super-versatile
  • Easy to acquire intense localized heat
  • Burns hotter
  • Produce less noise
  • Easy to make

CONS of the Coal Forge

  • Produces smoke
  • Dirty
  • Requires more expertise for proper work
  • Potential problems with neighbors
  • Environmental issue

Final Thoughts

So what’s the best type of forge? As you can see, there is no simple answer. It really depends on the type of projects you want to work on, the availability of the fuel, the skill set you are trying to achieve, etc. If you are a beginner and cannot wait to start hammering hot metal, a gas forge is way easier to learn. Also, if you are interested in making smaller pieces of metal such as knives, horseshoes, etc., then a gas forge is the ideal choice.

On the other hand, if you like the tradition of blacksmithing, or you want to make larger projects then a coal forge is the one to go for.

Leave a Reply