INCENSE BURNING vs. HEATING INCENSE
Overtime we've come to embrace the term incense burning. It's made its way into our everyday vernacular. We use it on a regular basis whenever we talk about incense and yet this term can be very misleading. This so called "burning" activity is actually better described as "smoldering" or in some applications even "heating."
Yes, it's true that we do light combustible incense (direct burning method) with a direct flame (i.e. a match or lighter). But once the tip is glowing the flame should be blown out and the incense allowed to slowly smolder.
If the flame is not extinguished the incense will burn up quickly and much of the intended fragrance will be lost. When an incense slowly smolders, its aromatic ingredients gently heat up and release their delicate fragrant "notes" into the air. When burning incense the scent is actually being released from the area just below the glowing tip.
You may have noticed that the smell just after the flame is extinguished is not as full bodied as it is after the incense has smoldered for a few moments. That's because the fast burning flame has destroyed much of the incenses intended aroma.
Non-combustible incense (indirect burning method) is never meant to come in direct contact with fire. It's placed on or near a heat source (e.g. charcoal ) so it can gently smolder or just heat up as it slowly releases its fragrance.