Why wet your Coal?
It all comes down to volatility.
In the USA bituminous coal is divided into high-volatile, medium volatile, and low volatile groups. Metallurgical grade Blacksmithing Coal would fall into the low-volatile group. The higher the volatile rating the more the coal fire will propagate or spread. Lower volatile coal SHOULD coke without moisture being added. Herein lies the rub.. Adding water does several things that work against us.
- In order to get the heat the water must be driven out. The BTU's that would normally be used to heat your material now must be used to drive the water back out first during which time some of the fuel is being consumed as well. Efficiency is gone.
- What happens when cold water hits a hot surface..... Stress. There is no way of judging what stresses are happening when we add water to our coal. Many of us have spent some amount of funds on a firepot, firebrick, refractory or other cement. Should we than shock with water causing fatigue? The thicker the cast iron firepot the more it can handle this shock but if we use a better grade of coal we can avoid much of this.
Another issue we have is in the misuse of the name "Blacksmithing Coal." In order to fit this classification it must be metallugical grade bituminous and contain less than 25% volatile matter. Does yours?
Next up: Why Fluctuate your forge air?