About Incense Stick

[gaurav]

I wonder why the incense stick does not give fragrance when its on fire, but does so when smouldering only. Any clues / answers?

Regards,

[scr4]

I would guess that when it is smouldering, the heated incense near the burning spot releases the fragrant, volatile gas into the air. When it’s burning, all the volatile gas is, well, burned.

[gaurav]

Well, am no Professor of Physics, but in my opnion smouldering and burning would create near same temperatures. And if that temperature is enough for burning, which would be combining oxygen with the volatile fumes so as to not give the fragrance, then that certainly can also happen when the stick is smouldering.

[Samson]

scr4 pretty much nailed it.

I could not find anything specifically about incense, but I think we can look at burning wood for an example.

According to How Stuff Works :

When the wood reaches about 300 degrees Fahrenheit (150 degrees Celsius), the heat decomposes some of the cellulose material that makes up the wood… Some of the decomposed material is released as volatile gases. We know these gases as smoke. Smoke is compounds of hydrogen, carbon and oxygen.

and

When the volatile gases are hot enough (about 500 degrees F (260 degrees C) for wood), the compound molecules break apart, and the atoms recombine with the oxygen to form water, carbon dioxide and other products. In other words, they burn.

So, in wood, smoke is formed around 300F and fire starts around 500F. I would think the smouldering incense is closer to the 300F end allowing the scented smoke to enter the air. Once the true fire starts any scent in the smoke is destroyed in the chemical reactions in the flame itself.