Guest Blog - Charcoal - Rockwood Charcoal

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Cooking at high temperatures requires good technique and some knowledge about charcoal.. I went to Jonathan Heslop - The Founder of Rockwood Charcoal for an education about charcoal. Jonathan has spent a great deal of time learning the details of charcoal - here are his answers to my 5 questions:

1 – What would make some charcoal better than others for high temperature cooking?

When rating lump charcoals against each other, all factors are directly tied to the percentage of carbonization (thus BTU/#.) For the highest possible temperatures, the higher the carbonization needs to be--which means more time in the kiln and more time to cool.

Charcoal is made by taking wood, then trying to burn out all the non-carbon extra compounds ...the water, tars, liquors, and other volatile organic compounds (VOCs) that produce smoke, ash, and blue flames. All of these compounds occupy the pores of the wood, like water in a sponge. During pyrolosis (kilning), these are all burned out making an extremely porous piece of charcoal. The higher the carbonization, the more surface area INSIDE the charcoal that the oxygen can reach. Firewood and briquettes have to burn from the outside in, whereas properly carbonized lump charcoal is mostly burning on the inside! Imagine trying to burn a newspaper--it will not burn very well, or hot, if it's rolled-up tight; however, if you crumble up every piece and stack them in a pile, it will be a mass inferno because of all the surface area the oxygen can now get to. Getting the airinside the charcoal's pores is what results in the hottest fire.

2 – I used a charcoal brand with huge chunks, but it wouldn't get as hot - why??

That's because it probably was not completely was charred wood (not quite charcoal yet.)   Water is heavier than carbon, and since charcoal is sold by weight, yields go up if you can cut a few days off the kiln and use less wood in the process; however, it is disingenuous to place the word "charcoal" on the bag.  True charcoal is light and brittle because all the compounds making wood fiber has been burned out of it--you can break apart by hand.  During sorting, bagging, palletization, and transport, it's going to break down.  If you still have HUGE chunks of charcoal after those processes, then you either had a bag that was VERY well nested and handled, or that piece isn't quite charcoal yet (i.e. it has wood fiber holding it together.)  That means the oxygen has fewer places to enter that chunk of charcoal, plus it's going to smoke and produce more ash as the volatiles are burned out.

I thought it was because there is less surface area in large pieces.

Forget about the outer surface area on any chunk of charcoal, because it's minimal in the grand scheme of things.  Properly carbonized charcoal (80%+ carbon) is going to have a total surface area of at least 250m2/g.  That means a golf ball sized chunk is going to have the surface area the size of a tennis court!  This is why properly carbonized charcoal can get so much hotter than wood--the oxygen is accessing all that surface area INSIDE of it.  This is also why charcoal is used for water filters, detoxification, and all kinds of medical uses--just like a dry sponge, it has tons of surface area for its small size and light weight.

3 – Why does some charcoal throw sparks?

Sparks and the pops are usually from moisture or the volatile organic compounds (VOCs).  When you hear the "pop!" it means water or VOCs just boiled inside a small cavity and blew out a little spot.  If that includes some of that VOC or charcoal dust, then it will burn fairly rapidly once it hits the heat and that's a spark.  Again, higher carbonization, means less water and VOCs, thus less sparks and pops.  There is always going to be some residual VOCs and moisture (the moisture the charcoal absorbs from the humidity in the atmosphere), so it's not uncommon to see an increased amount of sparks or flames on start up.  But after 10-15 minutes, they should be greatly reduced.

4 – Do different kinds of wood make the same quality of charcoal? Or - Sometimes you see sticks or actual boards - is that an indication that the charcoal is from a torn down building?

There are two parts to this answer: Just like cuts of beef, wood is quite different between species and must be kilned differently.  The final product is the most important part, so what you start with has to be fairly consistent.  Imagine trying to cook 120 tons of brisket and a tenderloin at the same temp for the same amount of time in a 6000 cubic foot smoker--there is no way it would work!  So, you have to start out with fairly consistent woods and hope for the best.  We are blessed in Missouri to have the nation's best supply of hardwoods and oak, hickory, maple, cherry, and pecan and they all burn about the same.  If we were to introduce a soft wood or an extremely hard wood like walnut into that mix, then it's not going to kiln evenly.  Undercarbonized pieces can produce some undesirable smoke--especially if it's something bitter like walnut.  So, if you start with consistent species with a consistent moisture content, and you use the same methods and kilns every time, then you're going to be setting yourself up for hopefully the most consistent lump charcoal that mother nature and fire will allow you to have.  Much like smoking a brisket where the "cow drives the cook", the same holds true with the wood deciding how it's going to kiln.  

The other factor is the actual source of the wood. Any charcoal manufacturer in the U.S. is going to be using slabs or other wood from mills.  Since it takes six pounds of wood to make one pound of lump charcoal, it's cost prohibitive and environmentally irresponsible to harvest a tree to just make charcoal.  Slabs are cut by a huge circular saw, so that means you will see 90 degree angles in the bag; but that doesn't mean it's "lumber".  There's a big difference between mill scrap and construction scrap.  Some cheap brands that have plywood, tongue & groove, molding, etc, are using construction scrap--which hopefully doesn't include treated woods, resins, etc (but since resins come from trees, unfortunately they can still claim it's "all-natural".)  Just about any charcoal you get from southern Missouri and northern Arkansas (the Mark Twain and Ozark National Forests), is going to be primarily oak, with some hickory, pecan, maybe some cherry or maple.  It's whatever is coming out of the wood mills that day that was too knotty, warped, or short to be sold as hardwood lumber to flooring, cabinets, furniture, pallet, and other companies sourcing rough-cut hardwood lumber.  In the end, with 80%+ carbonization, you'll never be able to tell the difference those woods.  Now if it's mesquite or a South or Central American wood, that's another story--you can definitely smell the difference in those.

4a – What are the differences with the non-domestic lump charcoals being imported to the U.S.?  

The charcoals coming from South and Central America are a "mixed bag" (pardon the pun.)  Some boast "huge, heavy & dense chunks", but if it's properly carbonized, it should NOT be heavy, nor dense.  In the end, everything living is carbon; carbon is going to be constant in its weight, BTU/#, etc since it's an element.  The only thing that can change is what's still in that charcoal--and if it's heavy and dense, they are selling you water, volatiles, and wood fiber, not charcoal.  A lot of those trees are from the walnut and cashew family, or other extremely hard nut woods which not only makes them difficult to carbonize all the way through, but also very bitter if they didn't get all the volatiles out of it.  Kudos to the companies that do have the technique to properly carbonize that stuff.  I doubt that process would be possible in the U.S. due to how we kiln (they do not follow our EPA, DNR, OSHA, etc. regulations) 

Any lump charcoal is the U.S. is going to be made from wood that would otherwise be discarded by the mill--the logging companies harvesting it are regulated by their state's DNR on where and what they have to replant.  At any U.S. charcoal plant, all smoke coming off kilns is fired to at least 1500F to burn out any particulate, and the dust has to be collected.  That dust, and the fines (small bits of charcoal) that get sorted out prior to bagging, are used for making briquettes most of the time.  We try to sell most of them for use in agricultural soil amendments and animal feed--hopefully getting as much of it buried back in the earth to offset carbon impact from what we are burning on the BBQ side of the business.  It is truly about the most green product you can find because it is zero waste.  You will only find this much regulation and attention to the environment in U.S., Canada, and European charcoal production.  Unfortunately, those three make up 5-10% of the world's charcoal production......most is produced in South America and Africa where very little regulation exists or is enforced when it comes to clear cutting forests, the emissions, and the safety & well being of the workers that produce it.  There was a heartbreaking documentary produced in the early 2000's called "The Charcoal People" that covered the deforestation, pollution, and horrific working conditions of charcoal production in Brazil.  Just search for it on YouTube, or use this direct link:

5 – If I want to have pizza without any smoke taste. What do I do?

If you're cooking with charcoal there's always going to be some smoke taste; in order to minimize it, start with a highly carbonized charcoal.  If you cannot break the charcoal apart by hand, it still has wood fiber in it, and wood fiber makes smoke.  Next, start with a full firebox of charcoal and let it burn for 15-30 minutes until the smoke turns to clear.  You're probably already doing this to heat the stone(s) up, but just make sure it has the time to cook out any remaining volatiles in the charcoal.  If you have to add charcoal mid-cook, give it another 10-15 minutes until you don't see any more smoke.  Finally, make sure you start with a clean kamado, oven, or grill.  If you're at 700F+ for 30-40 minutes and you're still seeing smoke, it's very likely it is residual fat and oil from previous cooks smoking, not the charcoal.  That grease produces an acrid smoke smell, very different from any wood smoke smell.  Be proactive--use a drip pan with fatty cuts of meat and regularly do a clean burn to minimize the gunk.

Bonus Quesiton- What is your favorite pizza 

Margherita, Neapolitan style......keep it simple, so you can taste the light wood smoke from the charcoal.

You can learn more about charcoal at his website -

Thanks for the education!