Do Bubbles Indicate the Quality of Oud?

Many circulate the belief that the appearance of bubbles on the surface of oud when heated is a conclusive proof of its quality and richness in resin. The truth is more precise than that: bubbles indicate the presence of a liquid substance that vaporizes, but they do not on their own distinguish between natural resin and an added oil. In this article we correct this common belief with fairness.

Why do bubbles appear in the first place?

When a piece of oud is heated, the liquid and volatile substances within the wood expand and come out toward the surface, forming small, shiny bubbles. The bubble is, in essence, a sign of the presence of a liquid that vaporizes with heat. And this liquid may be the natural fragrant resin formed in the wood, which is a praiseworthy thing.

But the problem is that the liquid itself may be an added oil in which the piece was soaked to raise its weight or feign richness, or even trapped moisture. All of these give bubbles on heating. So the bubble tells you that there is a liquid, not what this liquid is nor where it came from.

Why is it not conclusive proof?

Because it does not distinguish the source. A poor piece saturated with a cheap oil may bubble more abundantly than an excellent natural piece. Indeed, excessive bubbling may be a sign of suspicion, not reassurance, since it sometimes suggests an artificial soaking rather than a natural saturation. And so taking the bubble alone as a criterion is a common error.

The most genuine judgment comes from the accompanying scent, not from the bubble itself: is what rises a natural, evolving, clean oud scent, or a sharp, alien oily note that collapses quickly? As we showed in the gentle heating article, a gentle heat exposes the added oil by its scent, and the bubble is merely an accompanying phenomenon read in the context of the scent, not in isolation from it.

How do you read bubbles wisely?

Consider the bubble a secondary indicator added to the indicators, not a replacement for them. Notice it, but always link it to the scent, the weight, and the cross-section: a piece that bubbles moderately, gives off a natural, evolving scent, and confirms its richness by weight and color is more trustworthy than a piece that bubbles abundantly while its scent is faintly oily.

And with this we add bubbles to the list of "indicators that are misread" when taken alone. And in the following article we take up another common belief of this kind: does thick smoke indicate quality?