Originally Posted by Skip
Wow thank for that insight. I always wondered why it burned my food. lol
Funny I think I can speak to this not because of BBQ experience but work experience. I am a quality control specialist for an asphalt production facility. The quote around here is, "If you can't move air you can't make asphalt". The production facility is a big vacuum cleaner. Air is forced through the system to drag the heavy moistened air out of the chamber. The heavier the production and the greater the moisture the harder it is to create heat in the aggregate (sand and stone). Each aggregate particle has surface and internal moisture. The surface moisture leaves quickly while more therms and time are required to push the moisture from the micro fractures. During this process the stone will not heat above boiling point. I think the same thing goes for meat in a cooker. The barrier Zilla speaks of is that internal moisture being driven off. Now to speak to the full or empty chamber. When it has rained and we try to push the maximum ton per hour through the plant it gets choked out because there is too much moisture in the air. The air flow slows and stalls in some places. Since hot air rises the heat from the flame is pulled past these heavy pockets of moistened air and right out the stack. The hot air follows the path of least resistence and bypasses the heavy air. This then chokes down the flame because the moisture now changes the oxygen content for combustion. A pit works very similar. If the meat in the box is producing a heavy air pocket in the cooker then the heat will follow the path of least resistance and bypass the heavy air which will sit around the meat. Just my humble opinion.
While i don't fully understand the physics i can accept the analogy and have always agreed that there is more moisture in a fully loaded pit then a lightly loaded pit. are you describing a situation where there is reduced airflow in the proximity of the meat because of heavy air in the proximity? after a rain is the problem that the aggregate is wet or that relative humidity has increased or both. is one of the remedies to this to increase airflow and temperature/or fuel burned to maintain a constant temperature. so if you have a moist environment either from multiple birskets or from humidity introduced by a water pan, shouldn't the brisket your cooking behave the same way? this still doesn't explain how a foil wrapped brisket is analogus to a brisket cooked in a full cooker.