Bad Smoke

 
I am not sure of the physics, but it seems to me when the lump bed is struggling to ignite adjoining pieces of carbonized wood the 'bad smoke' is an issue. When the lump bed is hot the adjoining pieces of lump will ignite without producing the 'bad smoke'

As for how long it will take, sometimes when I use alcohol to light I get only a minute or two of 'bad smoke'. Using starter cubes, oil and paper towel for some reason 'bad smoke' lasts longer.

I use my had to know when the egg is ready. I put my had over the top vent for a short while and smell the aroma in my hand. If the aroma is acrid (bad smoke) I wait a little longer. If the aroma is pleasant the egg is ready. Sometimes there is more physical smoke and sometimes the smoke is very light or almost no visible smoke. The lower the dome temperature will usually have more physical smoke present.

GG

great analogy. Makes sense..

I am not sure how much different charred wood (lump) would burn as compared to wood, but as for wood...

The smoke is what actually burns and why the flash backs are so 'exciting'.

Here is a link that explains the physics.

What is fire?.

GG

Oh boy, I hope you're ready for this one.... Just remember, you asked for it. Heheheee.

The “bad smoke” is really volatile organic compounds, sometimes referred to as VOC’s. VOC’s are organic compounds that easily become vapors or gases, in this case when heat and charcoal is involved, but the gasses that come off other things like paint thinner, glue or cleaning solvents are also VOC’s.

If you’ve ever thrown any foreign thing into the bed of coals at a campfire or your fireplace (like a paper plate, a Styrofoam cup etc., the smoke you see for a few minutes are either VOC’s, or hydrocarbons. Even a new piece of wood tossed into a bed of coals smokes for a while until it gets up to temp. (Along these lines, many competition cooks using stick burning pits pre-warm wood [or charcoal] on top of their firebox before adding it to their cooking fire, you’ll understand this better in a minute).

So, back to your question…. Charcoal has some residual organic compounds, dust, dirt, and other foreign materials on it, and most likely in it. When you first light it you have a good heat source (propane or MapPro torch, starter cubes or gels, and in some cases lighter fluid), but usually we light charcoal in one spot for a barbecue fire, or 3 or 4 spots for a grilling fire. The VOC’s in those areas are immediately released, and while the fire is still taking root in the lit areas, the other charcoal in the cooker is warming up too. As it warms, it releases some VOC’s as well. In 20 or 30 minutes, the lit areas have become established, and the unlit charcoal has warmed and released some of it’s VOC’s. I often plan on 45 minutes to an hour for my fire to get where I want it. The color of the smoke coming from your top vent has changed from “white, thick and smelly” to “grey, thin and woodsy”. Later on it will turn to “blue, very thin, and fragrant”.



Part 2 of your question.... Since the fire moves slowly during a long cook, by the time it reaches new lump in your firebox, that new lump is better prepared for combustion than say a piece of lump from the bag. It’s the same if you have some flavor wood splits buried in within the lump, it’s also pre-warmed and ready for the fire when it reaches it.

Bonus Answer.... Now, the one thing you didn't ask about….,but I’m going to mention because I’m on a roll this morning, is particulate. In the early stages of a fire the smoke will contain particulate (think soot). You see this all the time in a fire place, it’s just harder to see in a barbecue pit. While the fire is becoming established, and you are getting your vent settings set correctly, this soot is carried by the smoke. If food goes on too early it can collect some particulate because particulates likes to attach to the surface of cool food. This is most noticeable on chicken because it has such a light skin. If chicken goes on too early, you can actually see fine spots and a premature darkening (like within the first 5 minutes), this coating will result in a bitter taste to your food. Try tossing a chicken wing on right after starting your fire, in 5 minutes when you remove it the dark color on the skin can be wiped off with a paper towel.

So, watch your top vent. If it's puffin' white, it ain't right. If it's blowin' blue, it's good for Q.

My theory: to get a good fire, you need airflow; fire needs oxygen. Burning produces carbon dioxide, which is heavier than air (air is mostly nitrogen, which weighs 28, and oxygen, which weighs 32; CO2 weighs 44).

If you don't have good airflow, the CO2 does not properly escape, thus smothering the fire as it is trying to light, which causes hot hydrocarbons which should burn to vaporize instead, producing bad smoke.

(the smoke a candle gives off after putting it out is actually vaporized wax (hot hydrocarbons that want to burn)... have fun... you can actually re-light a burned out candle by holding a match to the smoke... anyway, i digress...)

my first bge lighting, i didn't know what i was doing. shortly after lighting, i kept the bottom vents pretty wide open, but virtually shut the top. Bad airflow, nasty smoke... not so great day 1 with the bge.

so, i think an important way to avoid bad smoke is to keep the top open as much as possible, particularly when early in the lighting. get that airflow going.