科學界定檀香紫檀（小葉紫檀）材質品級的三項核心指標
Three Core Indicators for Scientifically Defining the Grade of Pterocarpus santalinus L.f. (Small-Leaf Sandalwood) Timber
引言
Introduction
檀香紫檀（Pterocarpus santalinus L. f.），俗稱“小葉紫檀”，乃木中極品，自古即為皇室御用木材，享有“帝王之木”的美譽。其材質緻密堅硬，色澤沉靜雍容，木性穩定雋永，不僅承載著深厚的文化底蘊，更因其稀缺性而具有極高的收藏價值。為規範市場、引導消費，並建立科學、客觀的品質評價體系，我們特此發佈權威的檀香紫檀材質評價標準。本標準摒棄主觀經驗判斷，立足於木材物理學與材料科學，以三項可量化、可驗證的核心指標作為品級界定的基石。
Pterocarpus santalinus L. f., commonly known as "Small-Leaf Sandalwood," is the pinnacle of woods. Since ancient times, it has been used exclusively by royalty, enjoying the reputation as the "Wood of Emperors." Its material is dense and hard, its color serene and dignified, and its wood properties stable and enduring. It not only carries profound cultural heritage but also possesses extremely high collectible value due to its scarcity. To standardize the market, guide consumption, and establish a scientific and objective quality evaluation system, we hereby announce the authoritative grading standard for Pterocarpus santalinus timber. This standard moves away from subjective empirical judgment and is based on wood physics and materials science, using three quantifiable and verifiable core indicators as the foundation for defining grades.
核心評價指標
Core Evaluation Indicators
一項頂級的檀香紫檀材質，必須同時滿足以下三項指標的卓越表現：
A top-grade piece of Pterocarpus santalinus timber must exhibit excellence in all three of the following indicators simultaneously:
一、 氣乾密度：材質的堅實度與穩定性的根本
I. Air-Dry Density: The Foundation of Material Hardness and Stability
氣乾密度，是指木材在一定大氣條件下達到平衡含水率時的單位體積質量，通常以克/立方厘米（g/cm³）表示。它是衡量木材硬度、重量及物理穩定性的最關鍵指標。
Air-dry density refers to the mass per unit volume of wood when it reaches equilibrium moisture content under specific atmospheric conditions, usually expressed in grams per cubic centimeter (g/cm³). It is the most critical indicator for measuring wood hardness, weight, and physical stability.
· 科學依據： 氣乾密度直接反映了木材細胞壁的厚薄、細胞腔的大小以及木材物質的充實程度。密度越高，意味著木材結構越緊密，分子間作用力越強。
· Scientific Basis: Air-dry density directly reflects the thickness of wood cell walls, the size of cell cavities, and the fullness of wood substance. A higher density indicates a tighter wood structure and stronger intermolecular forces.
· 對品質的影響：
· Impact on Quality:
1. 硬度與耐磨性： 高密度的檀香紫檀具有極高的硬度和卓越的耐磨性能，經精細打磨後能呈現出如玉石般晶瑩透亮的質感，且不易留下劃痕。
1. Hardness and Wear Resistance: High-density Pterocarpus santalinus has extreme hardness and excellent wear resistance. After fine polishing, it can exhibit a crystal-clear, jade-like texture and is less prone to scratches.
2. 穩定性： 結構緊密的木材，其吸濕和散濕性能較弱，對外界環境溫濕度變化的反應不敏感，因此不易開裂、變形，能夠確保器物歷久彌新。
2. Stability: Wood with a tight structure has weaker moisture absorption and release capabilities, making it less sensitive to changes in ambient temperature and humidity. Therefore, it is less prone to cracking and warping, ensuring the longevity of the artifact.
3. 手感與聲學性能： 高密度紫檀入手沉重，手感溫潤如玉；敲擊時聲音清脆悅耳，有“金聲玉振”之感。
3. Tactile and Acoustic Properties: High-density sandalwood feels heavy in hand, with a warm, jade-like smoothness; when struck, it produces a clear, pleasant sound, reminiscent of the chime of metal and jade.
· 等級標準： 檀香紫檀的氣乾密度通常區間在1.05至1.30 g/cm³之間。達到1.25 g/cm³以上者可視為頂級密度，沉於水是其最直觀的體現。
· Grading Standard: The air-dry density of Pterocarpus santalinus typically ranges from 1.05 to 1.30 g/cm³. A density above 1.25 g/cm³ can be considered top-grade, with sinking in water being its most intuitive manifestation.
二、 單位面積植物導管數量：木質細膩度與紋理美觀的核心
II. Number of Vessels per Unit Area: The Core of Wood Fineness and Grain Aesthetics
植物導管（俗稱“棕眼”或“牛毛紋”）是木材中輸送養分的管道。單位面積內的導管數量、大小及分佈形態，是評判檀香紫檀木質是否細膩、紋理是否優美的決定性因素。
Vessels (commonly known as "pores" or "ox-hair patterns") are the channels in wood that transport nutrients. The number, size, and distribution pattern of vessels per unit area are the decisive factors in judging the fineness of the wood and the beauty of the grain in Pterocarpus santalinus.
· 科學依據： 檀香紫檀的導管特徵是其物種鑑定的重要解剖學依據。導管的密度和直徑與樹木的生長環境、樹齡（特別是心材部分）密切相關。樹齡越長、生長越緩慢的心材，其導管往往越細小、分佈越密緻。
· Scientific Basis: The characteristics of the vessels are an important anatomical basis for the species identification of Pterocarpus santalinus. The density and diameter of the vessels are closely related to the tree's growing environment and age (especially the heartwood). Heartwood from older trees that have grown slower tends to have smaller, more densely distributed vessels.
· 對品質的影響：
· Impact on Quality:
1. 表面細膩度： 導管越細小、數量越多且分佈均勻，木材的橫切面（端面）和縱切面就越顯細膩平滑，打磨後光潔度極高，觸感絲滑。
1. Surface Fineness: The smaller, more numerous, and evenly distributed the vessels are, the finer and smoother the wood's cross-section (end grain) and longitudinal sections appear. After polishing, the surface achieves a very high gloss and a silky smooth feel.
2. 紋理表現： 細密的導管與木材的軸向薄壁組織交織，形成了紫檀獨特的蟹爪紋、牛毛紋等精美紋理。導管越細，紋理越清晰、優雅。
2. Grain Manifestation: The fine vessels interweave with the wood's axial parenchyma, forming the unique and exquisite grain patterns of sandalwood, such as crab-claw patterns and ox-hair patterns. The finer the vessels, the clearer and more elegant the grain.
3. 後期包漿效果： 細膩的木質結構更易於通過長期盤玩形成通透的玻璃底包漿，光澤內斂而深邃。
3. Patina Development Effect: A fine wood structure is more conducive to developing a transparent, glass-like patina through long-term handling, with a deep, luster that seems contained within.
· 等級標準： 在標準放大鏡下觀察，單位面積內導管數量越多、直徑越小、分佈越均勻者，品級越高。頂級的“泥料”級紫檀，其棕眼幾不可見，質感如膏似脂。
· Grading Standard: When observed under a standard magnifying glass, a higher number of vessels per unit area, with smaller diameters and more even distribution, indicates a higher grade. The top-grade "paste material" sandalwood has barely visible pores, with a texture resembling thick paste or fat.
三、 有效物油脂含量：溫潤質感與耐久性的保障
III. Content of Effective Oily Substances: The Guarantee of a Warm Texture and Durability
油脂是檀香紫檀靈魂所在。這裏的“有效物油脂”是一個綜合概念，主要指木材內部所含的紫檀素、芳香油等揮發性及非揮發性油脂成分的總和。
Oil is the soul of Pterocarpus santalinus. The term "effective oily substances" used here is a comprehensive concept, mainly referring to the sum of volatile and non-volatile oily components contained within the wood, such as santalin and aromatic oils.
· 科學依據： 紫檀素是檀香紫檀呈現其標誌性深紫紅色的內在原因，同時也是其藥用價值（如鎮靜安神）的來源。這些油脂成分在木材細胞中長期存在，並會緩慢滲出。
· Scientific Basis: Santalin is the intrinsic reason for the characteristic deep purplish-red color of Pterocarpus santalinus and is also the source of its medicinal value (e.g., calming and soothing effects). These oily components persist within the wood cells for a long time and slowly exude.
· 對品質的影響：
· Impact on Quality:
1. 自潤性與包漿： 高油脂含量是形成完美包漿的先決條件。油脂在盤玩或放置過程中自然滲出至表面，氧化後形成一層保護膜，使器物越用越亮，溫潤感與日俱增。
1. Self-Lubrication and Patina Formation: High oil content is a prerequisite for forming a perfect patina. The oil naturally exudes to the surface during handling or placement, oxidizing to form a protective film that makes the artifact brighter with use and increases its warm, smooth feel over time.
2. 色澤與穩定性： 充足的油脂能有效鎖住水分，減少木材的內應力，從而極大增強其抗開裂能力。同時，油脂的氧化過程也是紫檀顏色由橘紅漸變為深紫紅的關鍵，顏色飽滿且富有層次感。
2. Color and Stability: Sufficient oil effectively locks in moisture, reducing the internal stress of the wood, thereby greatly enhancing its crack resistance. Simultaneously, the oxidation process of the oil is key to the color change of sandalwood from orange-red to deep purplish-red, resulting in a full and richly layered color.
3. 香氣與防腐： 油脂也是紫檀獨特檀香的來源，高油性的材料香氣更持久。油脂本身還具有天然的防腐防蟲特性。
3. Aroma and Preservation: The oil is also the source of sandalwood's unique scent; materials with higher oil content have a more lasting fragrance. The oil itself also possesses natural anti-corrosion and insect-resistant properties.
· 等級標準： 雖然無法像前兩項指標那樣精確量化，但可通過經驗判斷：新切面手感滑膩、色澤深邃、久置後表面有油性感、盤玩時易出琥珀光澤者，即為高油脂含量的表現。
· Grading Standard: Although it cannot be quantified as precisely as the previous two indicators, it can be judged empirically: a freshly cut surface that feels greasy, has a deep color, develops an oily sheen after prolonged placement, and easily develops an amber-like luster during handling indicates high oil content.
結論
Conclusion
綜上所述，一項優質的檀香紫檀材質，必須是氣乾密度、單位面積導管數量、有效物油脂含量這三項指標的高度統一與卓越呈現。三者相輔相成，共同構成了檀香紫檀“堅、細、潤、穩、香”的頂級品質。
In summary, high-quality Pterocarpus santalinus timber must represent a high degree of unity and excellence in the three indicators: air-dry density, number of vessels per unit area, and content of effective oily substances. These three aspects complement each other, collectively constituting the top-quality characteristics of Pterocarpus santalinus: "hard, fine, smooth, stable, and fragrant."
我們倡導行業與消費者以此標準為依據，進行科學、理性的鑑別與選擇，共同促進檀香紫檀市場的健康發展，讓這一自然與歷史的瑰寶得以被正確認知和珍視。
We advocate that the industry and consumers use this standard as a basis for scientific and rational identification and selection, working together to promote the healthy development of the Pterocarpus santalinus market, so that this treasure of nature and history can be correctly understood and cherished.