Now you've considered fuels, the next aspect of a barbecue is the materials it is made from. All barbecues need to be heat resistant so the materials in them need to be "heat/fire proof" and there are quite a few. However, while there are wide variety of materials, I'm going to outline the most popular types. So lets look at the properties of each. Starting with the simplest, Earth.
Earth:
Soil, sand, gravel, and rocks all start off as magma, cool down, then over time are physically or chemically broken down into small pieces, sometimes re-assembled into new forms of stone once again by more heat and pressure, or sedimentation, then are broken back down into soil once again by chemical reactions or physical forces. The one thing you can be sure of, that your typical soil is more than able to handle the few hundred degrees that fire and barbecues need to deal with.
Originally, I guess the simplest form of outdoor barbecue is the "fire pit". Whether that's on a sandy beach, or soil, putting a fire in a hole allows the flames to be protected from wind, and also allows the fire to heat the surrounding earth. Tribes have used pits this way for thousands of years. Then often cooked their food over the fire directly, or by "baking" the food by covering it with "hot" earth. Of course, make sure you remember where you buried your food by marking it! Also, please note that hot sand/soil is not visibly different to cooler parts, so please be careful when mixing fire and sand in particular.
These days, most people think of earthen barbecues as "Earth ovens", sometimes called "Earthen ovens" which are made up of the kinds of dirt often used to make "mud huts" from. These range from mud, clay, and a mixture of mud/clay/straw called "Adobe". (No not the Photoshop people). Earth ovens are becoming very trendy with the more "eco friendly" people. The great thing about this is it can be very cheap to make, they work very well. You can shape them into really creative designs, and it's a great activity for the budding sculptors in your household. I've seen them shaped into three-dimensional sculptures of dragons, lady beetles, or if you prefer a simpler approach, domes and arches. You can make them tiny enough for a few loaves of bread or a pizza, or large enough for a bakery. However, if you're going down this route, I suggest starting small and then working your way up.
The downsides to Earth ovens is that that eventually, the oven will crack from the constant heating/cooling and need rebuilding or replacing. Also they need to be fully protected from the rain, so a comprehensive roof is another requirement. Some people have opted for just covering them in tarpaulins, but this requires the oven to be cool when the tarp is on it... and if there are leaks or any seepage, then your oven is at risk.
Aside from the aesthetics of the outside decorations, earth ovens come in a variety of designs. Some have a lower fire box with a chimney and an upper oven compartment. Others just have an oven space, and you preheat the oven by lighting a fire inside the oven itself, letting it heat the entire oven, then smother the fire, and allow the stored heat in the walls to radiate and bake your goods. I've even seen one with multiple parts, including an oven, and then an open fire pit in a solid adobe bench so you can cook "low and slow" in the oven, then sear it over open coals to get that delicious "bark" (the brown bits) afterwards.... or reverse that by searing first... if you prefer.
The really amazing thing about earth ovens is that you can simply crush up your old oven, re-soak it in water, then rebuild the oven over and over again. (I'd recommend renewing the straw if you use adobe). There's literally zero waste, and the entire thing is biodegradable. Get sick of it entirely, break it up and shove it onto the garden and water it in for some new soil.
Let's move onto the most common, metals such as steel, iron, and aluminium.
Metal:
Metals have long been used around fire. Many of them have a very high melting point, and can be shaped into pretty much anything we want. A barbecue can literally be as simple as a metal plate over a fire or almost a work of art, beautiful in design, and amazing in cooking capability. Some even have chained pulley systems to enable the chef to put the food closer/further away from the fire/hot coals to provide some temperature control. Others use adjustable air vents to do something similar. Some even use both methods. It's really no wonder why most modern barbecues available commercially are made largely, or even nearly entirely, of metal.
Whether you have a recently "sanitized by fire" hot plate that was formerly a rusty plough disk you found laying about in a field.... an ever popular "kettle" style of barbecue, or a full blown stainless steel outdoor kitchen with twelve burners, a couple of side burners, a rotisserie large enough to spit an entire cow on, and a huge stainless steel lid to smoke it all with.... chances are that your barbecue will have at least some form of metal somewhere.
Most barbecues are either powder-coated steel, or stainless steel. Metal is durable, it is difficult to break, it's relatively light, and if you look after it, can last years. If you're looking for a light-weight, durable, and portable barbecue, it's hard to beat metal. The price of barbecues made of metal run the full gamut from dirt-cheap (or even free) to many thousands of dollars.
The barbecue itself may have different parts made of differing metals. Even if your lid and frame is made of stainless steel, other metal parts may also include iron, such as "griddles", and firebox dividers, hot plates (that need to be "seasoned" like woks). Iron is a particularly heavy metal, but it has some amazing heat conduction and almost in a league of its own when it comes to searing things. However it is extremely prone to rust, and requires regular seasoning and other maintenance in order to make it last. Aluminium is also often used in frames, stands, or and trolleys, and other places away from the heat because Aluminium is an excellent heat conductor that makes it harder to maintain a stable temperature... and it's relatively low melting point.
Metal barbecues are almost completely impervious to most liquids and even gases, so they don't normally absorb the sort of fumes that can be created in a barbecue. So you can (although not recommended) light your Weber kettle with any type of fire lighter you like, the fumes will probably just vent. However, you can't do that with the ceramic, brick, or concrete equivalents, as they are porous, and certain fumes permanently embed themselves into the barbecue and impart awful flavours to foods cooked in them afterwards.
Metals also have the advantage of being resistant to impacts. Sure you can dent the lid, scratch some paint, and the barbecue will be fine. Even if it breaks, you can simply grind back to the metal, and weld cracks back together, or simply weld a new piece to "bandage" the gap. You certainly cannot do that with the ceramic barbecues, as they're likely to crack and be utterly destroyed. You can't simply glue a ceramic barbecue together again and expect it to handle the expansion and contraction of repeated heating/cooling cycles.
The down sides to metal are usually three fold:
- Metals generally have high heat conductivity, and are often used in thin sheets. As such, they often have very poor heat retention. In short, sheet metal acts like a heat sink, taking heat away from where it's needed. As such a metal barbecue needs more fuel to maintain temperatures. We're starting to see insulated models, that look like kamados (discussed below) but this still doesn't have the heat retention and even radiant heating of ceramic/earth/stone models.
- Rust. Rust and/or corrosion are the enemy of most metals. The number of rusty barbecues that end up tossed when they could simply be cleaned up is quite astonishing. Rust need not be the end of a barbecue's life. There are plenty of sites out there showing you how to clean up a rusty barbecue.
- Metal requires protection. Some parts that come in contact with food and/or deal with higher temperatures are coated in an air-tight coating like ceramic or enamel. If you manage to chip or remove the coating, the underlying metal will likely rust. Some protective coatings can be repaired, while others (such as ceramic coated heating grilles) cannot. Other parts (such as those forming the trolley carrying the barbecue) may be painted, or anodized or even galvanized, but these parts aren't often used in the hotter parts or in places they're likely to come in contact with food.
Metal cooking surfaces...
Metals have a place, but everyone has their idea of what the "ideal" metal is... especially when it comes to cooking surfaces. Some people prefer stainless steel for the easier cleaning that it provides. Others prefer ceramic coatings for their non-stick qualities. Some people actually prefer unprotected iron, and choose to season it with oils and fats to give it a non-stick surface.. and to get the flavours that only a seasoned iron plate imparts. I've used all three in differing barbecues, and I think each can be used to great effect.
Brick/Concrete:
I learned from my stone work skills course, that in the Australian Capital Territory, as long as you don't make anything over 1m high, and not load bearing, you do not need to seek approval of qualified people to build a simple brick or concrete wall. (Although, I strongly recommend that you read up on it first) Using this fact means you can build a barbecue yourself without breaching the law. However, please double check that with the local authorities if you plan to go ahead. Some people build a brick wall up to that height, then put an earth oven on top... or you can install a commercial barbecue or even an entire outdoor kitchen. Just make sure you build it with accurate dimensions if you go this way.
Sacrificing portability for a very low maintenance barbecue...
Somewhat like earth in heat retention, but without the sensitivity to rain, and quite unlike the metal models with their propensity to rust, are the brick and concrete barbecues. These aren't normally available in the shop, and certainly aren't usually considered "portable". However, with some DIY skills, you can build these from recycled building materials for very little cost. A former neighbour decided that wood was an easy way to fuel his barbecue (he used the off-cuts from his wood working business) found a guy with an excess of bricks and a couple of bags of cement, and off he went, building his custom barbecue complete with industrial grating for a grill, and a solid steel hot plate. A few weekends later, he was firing it up on his first cook. It was a substantial improvement over our old humble barbecue.
My neighbour didn't build a brick oven style barbecue though, so if you go down the "brick oven" track there's a few things you should know.
This type of barbecue, because of the large amount of material involved has fantastic heat retention. However, it takes a lot of fuel, or a long time, to heat it all up. Once you get them going however, you can cook for a surprisingly long time... even after the fuel has run out.
Variations on this theme include cubic or rectangular prism shapes. Also brick arches and domes, (often made in a similar way to the earth ovens mentioned above). Some even have shiny kitchen tiles (intentionally shattered) embedded an outer layer of concrete, arranged in mosaics for a fancy look. Some have in-built "rocket stoves" to get as much heat generated as possible. However, if you go this way, know that it is a very clean burning method, so if you want smoke, you'll need to add it in some other way. So fancy models might include side fire pits where the smoke is piped into and through the main chamber for smoking purposes. That you way have an efficient heat source, with the option to add smoke.
If you're going to go this way to build an outdoor oven I highly recommend having the food on some sort of rack or raised platform so you can get your tools underneath, or have the smoothest possible oven floor/shelf so you can easily slide your food in and out.
Ceramics:
Not quite earth, and not quite brick, are the ceramic barbecues. While they have far better heat retention than metal, they're also more portable than permanent fixtures. However, that's a relative statement, because they're heavy, very fragile, and really aren't designed to be taken places.... although I know people who have done this for major events.
A popular example is the Japanese style of barbecue, called a "Kamado". It is effectively, a ceramic version of the kettle barbecue. Only... it came out a few thousand years before the kettle barbecue. Aside from it's significantly heavier, and more fragile material, the Kamado maintains temperatures more reliably, operates on a fraction of the fuel, and can be easily dismantled for cleaning, or just set to incinerate to clean everything up in the barbecue... then all you need to do is simply sweep out the ash... once it is well and truly cooled down of course. :-)
The Japanese may have designed the Kamado, but the Americans have taken it to a whole new level. American companies such as "Big Green Egg", "Kamado Joe", and "Primo" are just a few. Ironically, it's now easier to get an American-made Kamado than it is a Japanese one.
Many of them are circular in shape, and come in sizes like mid-sized to large-sized flower pots, although some (like my Primo Oval XL) are more like an oval or simply massive egg-shaped flower pots.
Kamados are held together using tensioned metal bands and a metallic spring-loaded hinge to make opening the heavy lid easier. It's important that you regularly check the bands and hinges for loose bolts and gently tighten them up as the heating/cooling/movement vibrations can loosen them. If you don't, you may find that the lid flops off entirely and smashes on the ground. No warranty will cover that, and you'll need a new kamado.
So we've covered dirt/earth, metals, brick and concrete, and ceramics. That covers most barbecues. Still with me? If so, well done.