Blacksmith Gas Forge Basics
A Gas Forge May Be The Solution For Your Work Shop
The modern blacksmith may use either a solid fuel forge such as a coal forge or a gas forge The coal forge is still the most versatile, but a propane gas forge is the most convenient. Gas forges run at a bit over 2000 degrees Fahrenheit, which is certainly enough to do general forging.
The propane forge is actually an insulated box of various sizes and shape, that have one or more burners in the top or the side. The burners may be atmospheric or have an electric blower attached to them. The chamber holds the heat to heat the bar, and the burner provides the heat. Of course with a propane gas forge you are limited by what you can fit in the box.
The insulation in a blacksmith gas forge is a high temperature ceramic fiber. Trade names are Kaowool, Durablanket, or Fiberfax. This insulation allows the high temperature inside the gas forge but anticipates the outer shell from deteriorating. Hard or soft firebrick can also be used to lock the heat in the forge chamber.
In some blacksmith gas forges the insulation material is a castible refractory. This is more like a concrete that you mix up and shape to your gas forge chamber. This is more of a heat shield than an actual insulator. This type of gas forge will take a while to heat up. The refractory acts as a heat sink until it has soaked up enough heat that it reaches an equilibrium between the high temperature inside and the loss to the environment.
The refractory is more durable than the common fiber insulation, but you sacrifice thermal efficiency. It is also much heavier than the Kaowool insulation. The castable is much less flexible than the fiber insulation as well. This means that it will crack with repeated heatings. This may not be a problem as the pieces usually do not fall out.
The option of a gas forge is a great bonus to the modern blacksmith. For those that want a quick heat source with minimal maintenance, such as hobby blacksmiths it is ideal. Many professional blacksmiths make their living with a propane forge, and only use a coal forge occasionally.
The small size of a propane forge means that it can be quite portable. Many hobby smiths will easily move a propane forge out into the driveway, or just outside a shed for use. They are ideal for hammer ins as well.
Gas Forges are able to be purchased from many supplies or a blacksmith can make its own gas forge with only a few basic tools of a welder, drill press, and metal cutter.
I have been using a gas forge as my primary heat source for over 10 years now. I still use the coal forge, but the gas is so much cleaner. Both have their places and if your shop is big enough I would suggest having both available.