Have you ever seen Thin Blue Smoke - The highly desired color and amount of smoke coming out of the exhaust of a smoker. The thin blue smoke denotes a clean burn. A clean burn denotes great BBQ! No impurities!
Here is my explanation of what i am trying to convey: Wood does not burn directly. Rather, when heat is applied it first undergoes a process of thermal degradation called pyrolysis in which the wood breaks down into a mixture of volatiles and solid carbonaceous char. The cellulose and hemicellulose form mainly volatiles while the lignin mainly forms the char. Exactly what products are formed by each depends upon the temperature, heating rate, particle size, and any catalysts that might be present. The solid char remains in place. What goes up with the volatiles are a gas fraction (carbon monoxide and dioxide, some hydrocarbons, and elemental hydrogen), a condensed fraction (water, aldehydes, acids, ketones, and alcohols), and -- here we go! -- a tar fraction (sugar residues from the breakdown of cellulose, furan derivatives, phenolic compounds, and -- pay attention here -- airborne particles of tar and charred material which form the smoke. If oxygen is present and the temperature is sufficiently high, burning of the volatiles occurs. When temperatures are too low or when there is insufficient oxygen for complete combustion of the volatiles, smoldering occurs. This is characterized by smoking, the emission of unoxidized pyrolysis products. (This is the awful tasting stuff, creosote, that will give barbecue a bitter taste. (IE BBQ Exchange! ) If the temperature is high enough and sufficient oxygen is present, then flaming combustion occurs with less smoking and more complete oxidation of the pyrolysis products. Further pyrolysis of volatiles during flaming combustion may cause char particles (soot) to form. The remaining lignin char burns in the presence of oxygen in glowing combustion. These are my beloved coals that yield the thin blue smoke that makes great barbecue! And, that's why it is so important to preburn the wood to coals."
Conclusion:Thin Blue Smoke good , White smoke Bad!
Sincerely the BBQ Snob!
