Charcoal is typically made by compressing and slowly burning compounds that have a naturally high concentration of carbon, then cooling, packaging, and forming the material that remains. In general the result is a black, ashy solid that can be used for a number of different things, though it’s perhaps most popular in food grilling. The end product provides even heating and virtually no smoke. It is generally pretty inexpensive to make, too, which means that it's relatively affordable in most place. The material is usually created in bulk in massive furnaces and drying ovens, then shaped, molded, and packaged for sale. Manufacturers who make briquettes out of “specialty” materials or who infuse scents or oils may charge more, but the basic product is usually very economical on account of how simple it is to produce.
Drying and Heat
Charcoal literally goes through a trial-by-fire process, which makes it, in turn, a substance that can be burned to deliver steady, reliable, and long-lasting heat. Charring is the first step to this process, and is usually the one that takes the longest. Manufacturers start with carbon-rich materials that can burn down to an ash. Almost everything that has life on earth can be considered “carbon based,” but substances can vary dramatically when it comes to their concentration levels. The best choices for this process are usually wood, but might also include fruit pits, nut shells, or other plant products. Specialty manufacturers will often use certain kinds of wood, like hickory or slow-burning hardwoods, but in general any sort of solid wood will work.
The first thing that needs to happen is that these materials need to be dried. This usually happens in dedicated humidors or other closed chambers where the relative humidity can be manipulated to nearly zero. Then, they are moved to ovens where they’re subjected to an extreme heat of around 840° to 950°F (450° to 510°C). This is accomplished by placing the materials either in a kiln or a continuously-fed furnace called a “retort.”
Importance of Even Burning
Even though the burning period here is slow, manufacturers often need to help it be even, too. Unless the material is somehow stirred or rotated, it runs the risk of charring on one side before it’s even really smoldered on the other. This can lead to a lot of waste, and can also make the end product less predictable and consistent in terms of how it burns. In order to avoid these consequences, burning carbon is usually fed through a furnace with multiple hearths. Mechanical arms might also stir things periodically to ensure even burning.
Cooling Period
It’s also important for the finished product to cool before it is shaped or packaged. The ovens are typically so hot that allowing the charcoal to cool on its own can take days. Most manufacturers start by spraying everything down with cold water once it’s done in the furnace. They are usually left to dry in temperature-controlled rooms or chambers with regulated humidity.
Shaping and Packaging
While the cooled and blackened product at the end of this process is technically charcoal, it isn’t usually recognizable to consumers until it has been shaped. Most producers form their products into a briquette shape, which often resembles a puffed square or small pillow. To make these, the char is usually mixed with small amounts of binding agent, typically wheat or some other starch. The mixture is then dropped into a press or mold that cuts it into standard briquette shapes, which then go through a dryer to seal and set their form. Sometimes the char is also pressed into longer log-like shapes, which is more common for use in industrial-grade barbecues or grills.
After the material is shaped and cooled, the briquettes are bagged and sent off to store shelves, industrial plants, and other destinations. Bags are usually made of reinforced paper in order to help the product avoid moisture and stay ventilated. Under ideal conditions, it will last almost indefinitely and it doesn’t really expire or lost its efficacy.