The Zen Of Charcoal: How Charcoal Is Made And How Charcoal Works

"Why is it that one careless match can start a forest fire, but it takes a whole box to start a grill?" Anonymous

By Meathead

What's the best form of charcoal? Hardwood lump charcoal? Charcoal briquets? Wood embers? Extruded charcoal?

A lot of cooks swear by one fuel or another, but I'm here to tell you, it is much ado about little. The quality of the raw food is far more important. The seasonings are far more important. And without a doubt, getting meat off at the right internal temp is far far more important (see my meat temperature guide). You can spend a lot on expensive charcoal. Save your money and get a good thermometer (see my buying guide to thermometers).

The secret to successful cooking is controlling variables, the most important of which is heat. Our goal is to get a fuel that burns consistently from cook to cook.

Cut to the chase

We'll talk about the issues in a minute, but here's the bottom line: Harry Soo of Slap Yo Daddy BBQ, one of the top 10 competition teams year in and year out once told me "I buy whatever is on sale." Mike Wozniak of Quau, the 2010 KCBS Team of the Year and winner of scores of championships told me "I cook on whatever brand the competition sponsor is giving away for free. Charcoal is for heat, not flavor." Let's find out why.

Making charcoal

Charcoal is mostly pure carbon, called char, made by cooking wood in a low oxygen environment, a process that can take days and burns off volatile compounds such as water, methane, hydrogen, and tar. In commercial processing, the burning takes place in large concrete or steel silos with very little oxygen, and stops before it all turns to ash. The process leaves black lumps and powder, about 25% of the original weight, that packs more potential energy per ounce than raw wood. Char burns steady, hot, and produces less smoke and fewer dangerous vapors.

When ignited, the carbon in charcoal combines with oxygen and forms carbon dioxide, carbon monoxide, water, other gases, and significant quantities of energy.

The process of making charcoal is ancient, with archaeological evidence of charcoal production going back about 30,000 years. Making charcoal is still practiced at home in third world economies such as Haiti. Below is a fascinating 10 minute video of how to make charcoal briquets from agricultural waste by Amy Smith of D-Lab at MIT. She uses spent corn stalks and an old oil drum.

Because charcoal burns hotter, cleaner, and more evenly than wood, it was used by smelters for melting iron ore in blast furnaces, and blacksmiths who formed and shaped steel.

Commercial production was first done in pits covered with dirt by specially trained craftsmen called colliers. Below is Part 1 a great video sequence by Van Wagner about how colliers made hardwood charcoal in Pennsylvania from the 1600s to the mid 1800s, and how you can do it yourself if you are so inclined. Click here for Part 2, Part 3, and Part 4.

Hardwood lump charcoal

Hardwood lump is the next best thing to cooking with hardwood and it is fashionable for the same reasons that "organic" food is fashionable. It has this aura of being more natural. There are more than 75 brands and some are even varietal: Cherry, mesquite, coconut shell, and tamarind.

Hardwood lump charcoal is made from hardwood scrap and sawdust from from saw mills and from from flooring, furniture, and building materials manufacturers. Branches, twigs, blocks, trim, and other scraps are carbonized. The result is lumps that are irregular in size, often looking like limbs and lumber. Often they are carbonized to different degrees because there are so many different size lumps. Some brands, usually imported, are made by compressing sawdust into "logs" and extruding them under pressure, then carbonizing them and cutting them into uniform briquets.

Lump leaves little ash since there are no binders as in briquets. The big disadvantage is that lump is harder to find, more expensive than briquets, burns out more quickly, varies in BTUs (heat output) per pound (and thus, per cook), varies in wood type from bag to bag, varies in flavor from bag to bag, and often bags of lump contain a lot of useless carbon dust from improper filtering in the factory and rough handling in the stores. It is not uncommon to find rocks, metal pieces, and other foreign objects from the lumber operations where the wood is gathered. All this makes me fear that some of the wood could be chemically treated lumber. The process is not government regulated or supervised. Lump tends to produce more smoke flavor because large pieces may not be fully carbonized, but I prefer to get smoke by adding the wood of my choice. For definitive ratings and reviews of lump charcoal, visit Doug Hanthorn's website, a.k.a. the Naked Whiz.

Barbecue mythology says lump burns hotter than briquets, but the folks at Cooks Illustrated have found this to be a myth. They took two typical six quart chimneys and filled one with lump and one with briquets. They fitted two identical grills with seven digital thermometer probes each, and learned that by volume, not weight, and volume is how most of us measure charcoal, especially if we use a chimney, the two burned about the same for about 30 minutes, but after that the briquets held heat longer and the lump turned to ash faster. They repeated the test 11 times. Of course this only matters if you are seeking high heat. You can reduce the temp by reducing the amount of charcoal or the amount of oxygen.

Perhaps the idea that lump burns hotter came from the fact that there is more airflow through the pieces because of their irregular shape. The more air, the hotter it burns. This is really a factor when the charcoal is piled high as in a kamado grill. On the flip side of the coin, lump can produce more charcoal powder and crumbs which can fill the gaps between chunks and stifle airflow and make the fire burn cold. Remember air is fuel as much as is the charcoal, so I recommend that you discard the dust at the bottom of the bag.

Another myth is that lump has more flavor. Not if it is properly made. If all the wood is completely carbonized, converted to char, the flavor will be no different from other charcoal. But often lump is not properly carbonized. Often some of the larger chunks still have cellulose, lignin, and other wood components left in them, and when they burn they give off a flavor. This can be a pleasant addition to your food, but it isn't controllable. You don't know from one meal to the next what you're getting. Top pitmasters prefer to control this by burning pure charcoal and then adding wood of their choice to produce the quantity and quality of smoke they prefer.

Oh yes, there is one other factor a reader pointed out: The bags are lighter and easier to handle.

Charcoal briquets

Patented in 1897 by Ellsworth Zwoyer, the briquet really took off when, in the 1920s, Henry Ford, in collaboration with Thomas Edison and EB Kingsford, made lots of them from sawdust and wood scraps from Ford's Detroit auto plants. Cars were made in part of wood in those days. So Ford not only brought the world affordable cars, he created an industry that made backyard barbecue easy.

The company was later sold, and today Kingsford, a division of Chlorox, converts more than one million tons of wood scraps into briquets a year. There are five plants in the US. I visited the one in Belle, MO.

Kingsford briquets begin as sawdust and chips from mixed woods from timber mills in the Missouri countryside. Kingsford claims their mills don't make treated lumber and they are inspected by Kingsford quality control people to make sure there is not too much softwood. The sawdust arrives by truck and piled up in a mountain range that is inventoried by aerial photo. Moisture level is about 50%. A bulldozer pushes it into a conveyor that separates large chunks and foreign matter like rock.

The sawdust arrives in a conveyor (A) and then enters a huge rotating barrel (B) for tumble drying that takes the moisture down to about 35%.

Then it goes into special ovens called retorts (C). This is where the magic happens. With little air in the retort, the wood burns down to char, and comes out at about 25% of the weight that went in. The process drives off a lot of combustible gases which are used to generate energy for running part of the plant. Talk about a green industry: Using the waste (sawdust) of a renewable energy source (trees), and using energy generated by the charring process to run part of the manufacturing operation.

Once the char is cooked it is crushed and mixed with small amounts of anthracite coal (almost pure carbon), mineral charcoal, starch, sodium nitrate, limestone, borax, and sawdust. The additives act as binders, improve ignition, promote steady burning, and make manufacturing more efficient.

The slurry is then molded into their pillow shape with the K shaped channels that allow airflow during the burn. In the photo at right strips of the pillows are coming off a roller onto a conveyor belt. They are then dried, bagged, stacked, and shipped. The Belle plant runs 24/7 and produces an average of 550 tons per day. That's more than 61,000 of the 18 pound bags from this one plant per day!

Briquets typically produce more ash than hardwood lump since they contain more non-combustible materials. Some cooks complain about these additives, but there's a lot to be said for a fuel source that is rock solid consistent from bag to bag. Here's a really useful rule of thumb: There are about 16 Kingsford briquets in a quart, and 64 in a gallon. A Weber chimney holds about 5 quarts, or about 80 briquets. That's a known quantity of BTUs. There are too many variables in outdoor cooking, and having a reliable steady heat source is crucial.

Some folks say they can taste the additives in their food. I can't, and in a previous career I was a pretty well known wine taster and won several competitions. Self-igniting Match-Light charcoal, which has mineral spirits added to promote ignition, is a different story. Kingsford and government regulators say it is safe if you follow instructions, but I think they can taint the food. I don't use the stuff and I don't recommend it. Charcoal is easy to light with chimneys and I highly recommend them. Click the link to see how easy they are.

In 2008 Kingsford introduced a new line called Competition Briquets in a brown bag. Kingsford claims they are made with only char, starch as a binder, and a bit of borax to help it release from the manufacturing presses. Compared to the regular Kingsford Blue Bag briquets, they ignite slightly faster, burn slightly hotter, and produce less ash. Burn time is about the same. My friend, John Dawson, a.k.a. PatioDaddio, did a comparison test of regular Kingsford and Kingsford Competition. It is worth a read. Sensitive palates say Competition tastes better. Problem is they cost almost twice as much as the standard blue bag briqs which are frequently on sale, often 2 for 1 in spring.

There are other good charcoals out there. I like Royal Oak, and Duraflame Real Hardwood Briquets. Wicked Good 100% All Natural Hardwood briquets are made from just char and starch. Alas they are not widely available.

New products

There have been a few new charcoal substitutes introduced in the past few years. I have only tried one, called Lokii, and I am unimpressed.

Lokii is made in China and advertised as an "all-natural product." It is a giant seven cornered briquet about 5" wide and 2" thick. It comes in a plastic bag that is a pain to get open. As soon as it is opened I smelled something like solvent, despite the manufacturer's all-natural claims. The top is made of a different material than the bottom, and you must light the top. It is slow to ignite and then the fire creeps across the surface. V-e-r-y-s-l-o-w-l-y. I lit one, and the surface was all white by the time I successfully got the second lit. The first one was at full heat, well over 400°F, in about 25 minutes, while the second one was still smelly and incomplete. When I tried to move the first one with tongs it fell apart. I never got a good hot fire for cooking two ribeyes and dinner was an hour late while I went back to lighting regular charcoal.

I have since learned that these are used widely in rural areas in small coffee-can sized grills where the disks fill much of the interior, and the food they cook is usually in a pot on top. This makes a lot more sense.

In Asia coconut wood, ground to sawdust is often compressed and extruded in 3" logs, then carbonized, and cut into briquets. Several brands are trying to crack the US market. They seemed to work just fine in my limited tests.

So which is better?

Charcoal is for heat, not flavor. If you want flavor, it will come from vaporized drippings, laden with fats, sugars, and proteins, or from wood thrown on the coals. Watch the superb closeup slowmo video at right from the food scientists at ChefSteps.

I use Kingsford Sure Fire (blue bag) briquets for most cooking because I have a good feel for how many briqs will produce the desired temps in my cookers, because they remain constant from bag to bag, because I know they are at peak temp when they ash over (lump does not ash over), and because stores often place them on sale. I switch to Kingsford Competition for steaks, when I want max heat. I never buy Match-Light or any accelerant impregnated charcoal. Neither do I buy their charcoal with wood chips impregnated. I prefer to control the amount of wood by adding it manually. Briquets do create more ash which insulate the glowing coals and cool them a bit, but that makes them last longer.

Why don't I use lump? Because no two bags are the same, and within the bags the amount of carbonization from skinny twigs to thick chunks vary. That means some chunks will produce more smoke and even undesirable compounds.

Briqs give me consistency as well as better temp and flavor control and I'm all about control when I cook.

Bottom line

Some folks make waaaaay too much of charcoal. The quality of the raw food, seasoning, sauce, cooking temp, and serving temp faaaaar outweigh the impact of charcoal on outcome.

My best advice? Eliminate this variable. Pick one consistent brand of briquet, learn it, and stick with it for a year until you have all the other variables under control.

This page was revised 5/24/2013