When working in the blacksmith trade, one of the most important factors to consider is having the correct amount of heat for the tools you’ll be making. You may wonder, though, about the amount of heat a forge gives off.
Blacksmith forges can reach 3,500℉ (1,977℃) if you’re using a coal forge. However, the temperature varies based on the fuel, type of forge, and metal you work with. Not all forge welding projects require such a high temperature, nor does all types of fuel reach this heat.
The following information in this article will discuss a few topics related to this question, such as which temperature is required for forge welding, which fuel works for high temperature, and the amount of heat required for forging different types of metal.
Which Fuel Burns Hotter for a Forge Fire?
Wood, coal, and propane are typically the most popular choices for a forge fire.
Though all are viable choices for a forge, it is important to analyze the positives and negatives of all 3 forms of fuel to determine which you will use in the process of forge welding.
| Forge Type | Temperature (Fahrenheit) | Temperature (Celsius) |
| Coal Forge | 3,500℉ | 1,977℃ |
| Propane Forge | 2,300℉ | 1,260℃ |
| Wood Forge | 1,148℉ | 620℃ |
Wood Forge
Wood burns up to about 1,148℉ (620℃). This is not nearly as hot as the coal forge, but it’s still hot enough to melt some types of metal.
The burning of wood produces wood charcoal, which continues to burn until it’s reduced to ash. The charcoal is what causes the amount of intense heat required to weld.
A benefit to the way that wood burns is that it does not produce as much acrid smoke as other fuels, such as coal.
Furthermore, wood ash can be recycled for other means, unlike coal ash, which is rendered useless after burning.
When burning with wood, it is best to use smaller pieces: about 3 inches (7.62 cm) on each side or sticks that are 2×6 inches (5.08 x 15.24 cm).
Using smaller pieces causes the wood to charcoal quicker, which will produce more heat. This is particularly useful when forging with metals that hold a higher melting point, a consideration that will be discussed in more detail towards the end of this article.
However, the best results come from using hardwood that hasn’t been treated. Softwoods, unfortunately, burn at a faster rate, turn to charcoal quicker, and ultimately produce less ash.
Coal Forge
As stated at the outset of this article, coal burns the hottest at approximately 3,500℉ (1,977℃).
A large benefit to using coal is that it burns hotter than wood. Due to its level of efficiency, you would not need to use nearly as much coal as with wood. For example, a melon size amount of coal would burn within an hour, as opposed to a 5 gallon (18.9 liters) amount of wood.
However, when we burn coal, acrid smoke is produced at a high amount. It would be breathed in, cause blackening on your face and clothes, and ultimately create a less enjoyable welding experience.
If you are a blacksmith by trade, this is an issue that could be easily rectified with proper air ventilation.
If, however, you are a hobbyist or forge part-time, the amount of money required for such ventilation may not be worthwhile, depending on your level of usage of your forge.
Propane Forge
A particular issue with burning a coal fire is that the heat can often be difficult to control.
With propane, however, it is as simple as turning an on and off switch to ensure balanced heat. With this automatic system, propane is not prevented from reaching the heat required for forge welding.
Propane burns at about 2,300℉ (1,260℃), which is below coal but hotter than wood.
However, like coal, propane requires ventilation in order to be safe to use. If your forge is not properly ventilated, the burning propane can result in carbon monoxide poisoning, which is a risk that should not be treated lightly.
Coal fires will generally burn hotter than either wood or propane. Despite it’s intense heat though, a blacksmith who works as a hobbyist would be at a higher benefit to burning wood, due to the expense required to ventilate a forge both for coal and propane.
Wood is also the safest option in general, as the smoke it produces is not as harmful as coal or propane. However, the fuel and forge you decide to use will depend on the metal that you will be working with.
What Temperature is Required for Forge Welding?
Deciding on which fuel to use for your forge will largely depend on the type of metal that you work with. Every metal holds a different melting point and therefore requires different levels of heat in welding.
If you are a blacksmith by trade, you may work with various forms of metal that require varying levels of heat. It is, therefore, reasonable to consider using different fuel for different metals.
If, however, you are a hobbyist, you may only work with one type of metal, so it’s easier for your choice of fuel to be based solely on that metal.
Melting Point of Metal
The most common metals used in forge welding are iron, steel, and their adjacent counterparts. The melting points of each metal are as follows:
| Metal | Melting Point (Fahrenheit) | Melting Point (Celsius) |
| Stainless Steel | 2,750℉ | 1,510℃ |
| Carbon Steel | 2,500℉ – 2,800℉ | 1,371℃ – 1,540℃ |
| Cast Iron | 2,060℉ – 2,200℉ | 1,127℃ – 1,204℃ |
| Wrought Iron | 2,700℉ – 2,900℉ | 1,482℃ – 1,593℃ |
It is important to note that when forging steel, your forging temperature should generally be lower than your metals melting point.
When a metal is brought to it’s forging temperature, you are able to shape and mold it without the causation of cracks in the metal.
Iron has a low melting point, so this is most necessary for steel, or other metals with a similar melting point.
The forging temperature for these same metals are as follows:
- Carbon steel forging point- 2,246℉ (1,230℃)
- Stainless steel forging point- 2,003℉ (1,095℃)
Therefore, the fuel and heat required for your forge will depend on the metals that you regularly work with.
For metals with a low melting point such as iron, wood is an ideal form of fuel. For metals with higher melting points such as steel, using coal or propane would be a reasonable choice for your weld.
It is, of course, possible to weld these metals with all the above-mentioned fuels, but for a high-quality weld, it is best to choose a fuel more useful for the specifications of your metals melting point.
Conclusion
When using coal, the hottest form of fuel, your forge may reach up to 3,500℉ (1,977℃).
Temperatures will vary, however, depending on the fuel available to you. If you have decent ventilation in your workspace, coal, and propane are ideal sources of fuel.
However, if you do not have access to proper ventilation, you may have to settle for a lower temperature burn in the form of a wood-burning forge.
When deciding which fuel you will use, it is important to take into consideration the types of metals you will be working with, as their forge and melting point will determine the level of heat required from your fire.
Proper selection of your forge by taking these variables into account will not only guarantee the proper quality of your forged pieces but offer you further enjoyment in your practice of forge welding. Also, don’t forget to take into account the price of blacksmith forges.
Thanks for reading and have fun with your future projects!
Cheers, tools owners!
