What Is Agarwood? The Structure of the Resin-Saturated Wood and Its Forms

When we speak of oud, we often begin from its form closest to the eye and the hand: the wood. But what is agarwood specifically? And why is a part of the trunk a precious agarwood while the rest of it is an ordinary wood with no aromatic value? In this article we focus on the wood itself: its structure, how it is saturated with the resin, the difference between its dark rich regions and its light regions, and the forms in which it reaches you. And it is an axis of the complete guide to oud, and it complements our introductory article what is oud?, which defines the aromatic material in its general form.

1. What is agarwood?

Agarwood is the wood saturated with the aromatic resin inside the trees of the two genera Aquilaria and Gyrinops. For not all the wood of these trees is agarwood; rather it is specifically that section of the tissue of the trunk in which the resin accumulated until its color, its weight, and its scent changed. In a concise phrase: agarwood is the woody tissue that embraced the resin so it became a carrier of it.

And to clarify the difference, imagine the trunk of the tree cut crosswise: you will mostly see a light-colored, light-weight wood filling most of the section, interspersed with darker and heavier regions or veins that are the sites of the concentration of the resin. Those dark regions are the precious agarwood, whereas the light wood surrounding them is the ordinary tree wood that is not counted as oud even if it is from the same tree.

It is important to distinguish here between the wood and the resin without confusing between them: the resin is the dark aromatic material that the tree secretes, whereas agarwood is the woody tissue that was saturated with this resin. The two are inseparable in a single piece, but they are not one thing; for the resin is the source of the value, and the wood is the vessel that carries it and displays it. And we devote to the resin itself an independent axis in this guide for whoever wants to expand into its nature and the chemistry of its formation.

And when we say "agarwood" we are referring to the solid form capable of being burned or carved or ground, distinguishing it from oud oil, which is the aromatic oil extracted from this wood by distillation. For both return to the same material, but this article is concerned with the wood in its solid form specifically, since it is what the buyer sees and touches mostly in the market.

2. How ordinary wood transforms into agarwood

Agarwood is not born as oud, but begins as an ordinary light wood then transforms. And the essential driver of this transformation is the injury: a wound in the trunk, or a break, or the entry of a fungal infection into the internal tissue. Then the tree reacts defensively so it begins to secrete the aromatic resin around the site of the injury, which paves the way for the neighboring wood to be saturated with it gradually.

This saturation does not happen all at once, but extends over the course of long years that may lengthen or shorten according to the tree and its conditions. And with the passage of time the resin penetrates into the woody tissue, so its weight grows heavy and its color darkens and its scent deepens, until the pale light wood transforms into a dark, dense, aromatic material which is agarwood. So oud, then, is the yield of injury and time together, not the product of an ordinary natural growth.

And we content ourselves here with this summarized picture because the mechanism of formation in detail — the types of injury, the role of the fungi, and how it is induced in the farms — is an independent axis in this guide that we detail in the article how oud forms. Likewise the historical transformation from gathering wild oud to cultivating it affected the abundance of this wood and the manner of its production, which we addressed in from wild oud to the farms.

And the practical conclusion is that what makes the value of agarwood is not the age of the tree alone, nor the size of the trunk, but the amount of resin with which the wood was saturated and the length of the period in which it accumulated. And for this reason the pieces of agarwood vary a great variance even within a single tree, according to their nearness to the sites of the injury and the density of the resin in them.

And it is well to remember that this transformation is a slow process of uncertain result: for not every injury leads to an abundant resination, and little resin may form that does not suffice to transform the wood into an oud of value to mention. This amount of uncertainty at the source is an authentic part of the nature of agarwood, and it is what explains why it remains a scant material however the means of cultivation develop, and why what is offered of it varies in abundance and quality from one season to another.

3. The structure of agarwood: the rich against the light

If you look at a piece of agarwood up close, you will mostly not find it a single homogeneous color, but a mixture of dark regions rich in resin and others lighter, less saturated. This contrast is the essence of the structure of agarwood: the resin does not distribute equally in the tissue, so there arises something like veins, lines, and dark spots that intersperse a lighter background.

The dark rich regions: they are where the resin concentrated densely, so the wood in them became heavier in weight and deeper in color — inclining to the dark brown or what approaches blackness sometimes. And these regions are the heart of the value of the piece, since from them comes the density of the scent and its persistence upon heating. The light regions: they are where the resin diminished or was absent, so the wood remained closer to its original state: lighter in color, lighter in weight, and weaker in scent.

And because the resin is heavier than the bare wood, the weight became an approximate — not decisive — indicator of the richness of the piece in resin: the more the saturation increases, the more the weight increases relative to the size. And upon this very principle rested the idea of "sinking oud" which sinks in water for the excess of its density, and it is a historical tale connecting the density and the density of the resin that we addressed in the tale of sinking oud. But one ought to beware of generalization; for the weight and the color are two indicators to be taken as a guide and a decisive judgment is not built upon them alone, since a dark color can be manufactured or an apparent weight increased by dishonest means.

And this structural variance — between the rich and the light within a single piece — is what explains why the price of agarwood differs a wide difference even between two pieces from the same source. For the piece dominated by the dark high-density regions is not like the piece dominated by the light wood, even if they resemble each other in size. As for the details of the appearance of natural agarwood — its colors, its veins, and how you read them — it is an independent axis we devote in the article "the appearance of natural agarwood."

4. The forms of agarwood

Agarwood reaches the consumer in several forms, differing in size and use but all of them the same wood in different guises:

The whole pieces: relatively large blocks or pieces of the resinated wood, and they are the closest to the natural image of oud, acquired by some enthusiasts for display or for burning on occasions, and smaller pieces may be carved from them. You find them within the natural oud collection.

The broken pieces and chips: small and medium pieces broken from the wood, prepared for direct burning on the coal or the electric burner for daily or special burning. And they are among the most traded forms of agarwood for the ease of their use, and you find them in the oud chips collection.

The filings and the powder: the wood ground or filed into fine granules or powder, used in burning and the making of blends and made bukhoor. And you find it in the oud powder collection.

And the practical rule is to choose the form according to your intended use, not the reverse: for whoever wants an easy daily burning, the chips and the broken pieces suit him, and whoever acquires for display or occasions may prefer the whole pieces, and whoever makes blends needs the powder. And there is no "best" form absolutely, but a form more suitable for your need and your manner of use.

5. Agarwood against ordinary wood

The difference between agarwood and ordinary wood is not a difference in the type of the tree alone, but in what is inside the wood of resin. For the ordinary wood — whether from the Aquilaria tree itself before it becomes resinated, or from any other tree — is a light, light-weight wood almost without an aromatic scent. As for agarwood, it is that wood when it is saturated with the resin so it gains the color, the weight, and the scent. The resin, then, is the dividing line: no oud without resin, whatever the source of the wood.

And for this reason it is not valid to judge a piece to be agarwood merely because it is dark in color or heavy, for an ordinary wood may be dyed or treated to appear so. The real standard is the presence of the resin actually in the tissue, which appears upon heating when the deep, stable scent that the dyed wood does not give is emitted.

And there is another difference worthy of attention: agarwood does not burn as the ordinary firewood burns, blazing quickly, but rather reacts with the heat a slow reaction that melts the resin in it and releases its scent without a noisy flame. This behavior upon heating is among the clearest things that distinguish the wood saturated with the resin from the bare wood. And this detailed comparison — with its practical signs and methods of distinguishing — we devote in an independent axis of the guide titled "the difference between oud and ordinary tree wood," and we content ourselves here with establishing the principle.

6. How agarwood looks and smells

In a quick glance, the color of agarwood ranges between the light brown and the dark brown and what approaches blackness in its regions richest in resin, with dark veins and lines interspersing a lighter background. And its texture inclines to hardness and density in the rich pieces, and may leave a perceptible resinous trace. This is a summarized picture only; as for the detail of the appearance — the colors, the veins, and how you read them with your eye — it is an independent axis we devote in the article "the appearance of natural agarwood."

As for the scent, agarwood in its cold state may be relatively faint in trace, but it reveals its layers upon heating or burning: then a deep, complex scent is emitted that varies from one piece to another and from one origin to another. And we avoid here describing the scent a decisive description, because it is an individual experience difficult to reduce into words, and your nose is a truer judge upon it than any written description. And we devote to the scent of oud and the description of its layers an independent axis in this guide. And for whoever wants to be reassured about how we examine the wood and evaluate it, we clarify that on the quality-control page.

7. How you verify authentic agarwood

After we have known what agarwood is and how its structure forms, the practical question for the buyer remains: how do you become reassured that what is in your hands is a real agarwood? The answer rests upon indicators taken as a guide together, not upon a single decisive sign:

The apparent trace of the resin: search for the veins and the dark non-homogeneous regions that indicate the saturation of the wood with the resin, not for a flat homogeneous dark color that may be artificial. The weight against the size: the piece rich in resin is heavier than its light counterpart, and the weight is an approximate indicator of the density even if it is not a sole proof. The scent upon heating: authentic agarwood, the layers of its scent appear and persist when it is heated, and the senses are a truer judge than the commercial name.

And added to that is the transparency of the origin and the grade: for the serious seller mentions to you from where the wood came and which grade it is, and does not content himself with loose phrases. And it is useful that you understand how the grades of oud are classified, since it did not historically know a unified global system of grading, which we detailed in the history of oud grading. And we arrange our wood in a ladder of five grades extending from the daily grade to the collectors' grade of high density, so that every searcher finds what suits his need and his budget.

And the honest advice remains that you begin with the experience before the commitment: the scent and the density, a name does not describe them nor a picture, and for this reason the best thing to begin with is a small sample by which you test the wood yourself, which we make possible on the samples page within the sample kits collection. And beware the impossible price; for high-density agarwood is not sold at trifling prices, and the exaggerated cheapness is a sign of warning, not an opportunity.

Read also

For a wider deepening, begin from the complete guide to oud which gathers all the axes of the subject in one place, then look at our introductory article what is oud? to understand the aromatic material in its general form. And we are working on devoting independent articles to interconnected axes such as: how does oud form?, and the difference between oud and ordinary tree wood, and the appearance of natural agarwood — we add the links of what remains here successively whenever it is completed.