Here’s a summary of my knowledge pertaining to smoke rings. There’s a good chance that I’ll get some of the facts wrong because I’m just going on memory and most of this info is based on internet research which could have been bad.
Pink meat (i.e. ham, smoke ring) is a result of a chemical interaction between nitrogen compounds and myoglobin found in muscle tissue.
Nitrogen compounds (gaseous) are generated by burning organic matter.
Specific bacteria on the surface of you meat have the ability to convert the nitrogen compounds (nitrate?) in the gas released by burning organics into nitrogen compounds (nitrite?) that will react with the myoglobin, possibly through some metabolic process. Since the bacteria are living, to get a smoke ring, you need to be feeding the bugs nitrogen, and the bugs need to be in the “unsafe” zone (40*-140*). You’ll see it often stated that smoke ring formation stops at 140*, this would be a result of baking your bacteria. Surface meat temps are key, because that’s were the bugs are doing the nitrogen conversion, so don’t be fooled by a <140 * internal, thinking your smoke ring is still forming.
As far as I know the reaction only occurs at the surface, nothing penetrates (i.e. “smoke”) the meat to create the deep ring. The depth of the ring is often mentioned as being produced by “chain reactions” that start at the surface and proceed into the meat. This part is a little unclear to me, but I try to think of it as the nitrogen compounds are converted at the surface and they are what diffuse into the meat, not smoke. Therefore, depth of the ring depends on how much nitrogen gets on your meat, how much is converted by the bacteria, and how much diffuses down before the meat starts pushing back. This last part is my conclusion, so consider that before taking it as fact.
I deliberately was nonspecific about terms like smoke and never mention wood. It appears that, while being capable of producing flavorful (aromatic) compounds, burning wood is not good at producing nitrogen compounds. Ask anyone who runs an electric smoker and they’ll tell you that wood chips alone do not produce a smoke ring. You’ll find it common for people to recommend burning a bit of charcoal on the hot plate along with wood, if they want a ring.
I’ve found that I even get more of a ring when I use briquettes as opposed to lump. I supposed this could be due to what is added to the briquettes to make them, or possible due to the lower temp that briquettes burn at. And I’d be willing to bet you could get an even better ring if you used coal (acid rain, or nitric acid, comes from coal plants). The key here, is to realize that wood smoke will lay a thin layer of flavorful aromatics on your meat, but the bulk of your fuel will be the nitrogen source.
I can’t say that I’ve done much in the way of applying this knowledge to create a better ring. I do put my meat on cold, I usually put it on the wsm after it has preheated somewhat (hopefully enough to avoid creosote condensation), and I usually go for a long, controlled ramp up in temp. Like Larry, I value flavor first, but I do keep an eye out for other controllable variables.
