The smoke ring has become synonymous with well smoked meat, the reality is you don't even need smoke to create a smoke ring.
Now we all eat with our eyes, so if you didn't see a nice pink ring on a slice of brisket it would probably cause you to ask if the pit master was too busy smoking something else. And to be honest it would be pretty hard to smoke a brisket and not get a smoke ring, but you can definitely affect how big of a smoke ring you will get in several ways. So let's look at the science of a smoke ring to understand it a little more.
As a lot of BBQ nerds probably already know the smoke ring is nothing more than the outside of the meat getting pickled by the nitric oxide (NO) and carbon monoxide (CO) in the smoke. So this is really a reaction of the meat with the gasses in smoke, not the actual smoke particles that impart smoke flavor. Therefore the size of the smoke ring has no real bearing on the actual amount of smoke flavor you will get in that bite of brisket. You can even fake a smoke ring by using curing salts, see hot dogs, ham, and corned beef.
Now I can't imagine a restaurant actually doing this because, why bother when the smoke ring will form all on its own. I could imagine a contestant doing this at a BBQ competition if they were really desperate for a thick smoke ring. Which is why the smoke ring is not supposed to be a factor when judging. But let's face it, a smoke ring is part of the visual appeal and if it isn't there it just won't look right.
So for you home smokers a couple tips on ensure a nice thick smoke ring:
1) Wet Surface - Any moisture, whether it is a mop or baste or spritzing will help pull in these gasses(remember it is gasses not smoke) and pickle the outside of the meat. The more you baste/mop/spritz the better.
2) Brine Your Meat - Similar to mopping your meat, the salt in the brine will force the meat to retain extra moisture. This then adds to the smoke ring creation.
3) Don't Cake on the Dry Rub - Anything that can block the NO and CO from the surface of the meat can hinder smoke ring formation.
4) Wait on Wrapping - If you plan on wrapping your meat, make sure to wait as long as you can to keep the gasses in contact to form the smoke ring.
5) Trim the Fat - Now I would never suggest your trim all the fat, because it helps with moisture retention. The thinner you trim the fat the more smoke ring formation you will get. Fat is permeable and you can get a smoke ring under the fat cap, but you have to keep it very thin, like under 1/4 of an inch.
6) Go Low and Slow not Hot and Fast - While you can smoke an excellent brisket hot and fast, you will reduce the total amount of time the smoke ring has to form.
7) Curing Salt - Yes this will work too, but honestly, if you have to resort to this you should ask yourself what you are doing with your life.
So while a smoke ring is no guarantee of great BBQ, we eat with our eyes. So it definitely helps with the mind games of thinking the food will be good. Happy Smoking!