《理解木材》· Understanding Wood · R. Bruce Hoadley · Taunton Press 1980

《理解木材》（Understanding Wood）是 R. Bruce Hoadley 的第一部著作，副题「木工的木材技术指南」。封底推荐语写道：「如果你是木工，就知道木材是一种美丽但有时难以驯服的材料。木材为什么会那样表现？《理解木材》告诉你关于木材本身的一切，以及如何与这种偶尔桀骜不驯的材料合作，而不是对着干。」

作者在前言中说明写作动机：科学界已积累大量木材知识，「但几乎没有任何成果被转化并解释给个体工匠」；人们写满大宗木材干燥的宏篇巨著，「却几乎找不到如何干燥从单棵树上锯下的几块板子的指导」。他还要直面木工圈流传的错误信息——「干腐」这类误导性术语、「木材需要呼吸」这类迷思。他借用 1875 年英国海军部木材检查员 Thomas Laslett 的话概括此书宗旨：木材「数量庞大、至关重要，却普遍鲜为人知」，实用手册「太有必要」。

全书从树开始：树木的生命与生长如何影响木材的花纹与外观，如何识别 54 种常见国产及进口木材；继而探讨水与木材的相互作用、木材涨缩及其应对；再分析物理性能（尤其是强度）如何决定最佳加工方式；最后从工匠与木材科学家的双重视角，考察切削、弯曲、接合与紧固等日常操作。用作者的话说，本书「将科学推理和方法与工匠的敏锐判断融为一体」——每一位与木材打交道的人，工匠、建筑商、工程师、设计师，都将受益于这种彻头彻尾的研究方法。

目录 · Contents

第1章 · 木材的本性 · CHAPTER 1 · The Nature of Wood …… 1

• p.4 · 生长轮 · Growth Rings
  形成层的活动只要环境适宜、树木康健便持续进行，温带气候的年周期造就可见的生长层。
  EN · Activity of the cambium continues as long as environmental conditions are suitable, producing visible growth layers.
• p.5 · 木纹 · Grain
  「木纹」一词有五十多种用法、约十类范畴，本节依术语表逐一界定。
  EN · The word grain has well over 50 uses in some ten categories, each defined in the glossary.
• p.6 · 边材与心材 · Sapwood and heartwood
  幼树干全部负责输水故称边材；随树干加粗，中心形成心材，边材宽度因种而异。
  EN · Sapwood conducts sap in the living tree; as the trunk grows, the inner core becomes heartwood.
• p.7 · 结构排布 · Structural arrangement
  鉴于生长层排列与细胞走向，宜从三维角度认识木材结构：横切、径切与弦切面。
  EN · Wood structure is best considered in three-dimensional terms: transverse, radial and tangential planes.
• p.8 · 密度与比重 · Density and specific gravity
  密度是预测木材强度、硬度、加工性与握钉力的最重要单一指标。
  EN · Density is the single most important indicator of strength in wood.
• p.10 · 系统分类 · Systematic classification
  木工不必成为分类学专家，也能熟悉木材的命名与科属。
  EN · The woodworker need not become a taxonomy expert to become familiar with the naming and classification of woods.
• p.11 · 细胞结构 · Cellular structure
  了解解剖细节有助理解软硬木之别及种内变异。
  EN · An acquaintance with anatomical detail increases understanding of the broad differences between softwoods and hardwoods.
• p.12 · 软木 · Softwoods
  针叶材细胞以管胞为主（占体积九成以上），另有木射线与树脂道。
  EN · Coniferous cell types are over 90% tracheids by volume, with ray tissue and resin canals.
• p.14 · 硬木 · Hardwoods
  多数阔叶材无树脂道，木射线大小悬殊，细胞类型远多于针叶材。
  EN · Most hardwoods lack resin canals; rays vary widely in size and cell types are far more numerous than in softwoods.

第2章 · 木材的花纹 · CHAPTER 2 · Figure in Wood …… 19

• p.26 · 节疤 · Knots
  有些不规则提升价值（如特殊花纹），有些被传统视为缺陷；作者呼吁善待自然的不规则。
  EN · Some irregularities increase value as distinctive figure; others are branded defects—yet nature’s irregularities deserve reserved judgment.
• p.29 · 异常木材 · Abnormal wood
  髓心周围最初几个年轮常为幼龄材，性状与成熟材不同，速生针叶树上尤甚。
  EN · The first growth rings around the pith form juvenile wood, atypical of mature wood, especially in fast-grown conifers.
• p.33 · 真菌 · Fungi
  条件适宜时木材可永久保存，但木材可生物降解，腐朽是森林延续的必要环节。
  EN · Wood lasts indefinitely under favorable conditions but is biodegradable; decay is as necessary to the forest as the sprouting of seed.
• p.37 · 虫害 · Insect damage
  多种昆虫在活树、原木、锯材或成品中为害，如蝇幼虫在树干中造成的髓斑。
  EN · Many insects damage wood in trees, logs, lumber or finished products, e.g., pith flecks caused by fly larvae.

第3章 · 木材识别 · CHAPTER 3 · Wood Identification …… 39

• p.42 · 观察要点 · What to look for
  先熟悉相关结构特征（心边材、颜色、气味等），并在后文代表树种照片中对照。
  EN · First gain an acquaintance with the pertinent structural features, pointed out in photos of representative species on pages 47–65.
• p.44 · 物理性能 · Physical properties
  颜色、气味、重量等肉眼可感的性质，单独或组合起来常能大幅辅助鉴定。
  EN · Color, odor and weight are properties perceived with the naked eye that can greatly aid identification.
• p.45 · 识别技术 · Identification techniques
  不存在唯一最佳技术：已知样本、手册照片与检索键各有利弊。
  EN · There is no single best technique; known samples, manuals, photographs and identification keys each have advantages.
• p.47 · 宏观照片 · Macrophotographs
  随后十八页呈现 54 个常见树种的宏观照片，纵览识别所需的基本解剖特征。
  EN · The next 18 pages present macrophotographs of 54 common species, surveying the basic macroscopic anatomical features.

第4章 · 水与木材 · CHAPTER 4 · Water and Wood …… 67

• p.68 · 自由水与结合水 · Free water and bound water
  木材中的水分指树液或其他来源的水，分胞腔中的自由水与胞壁中的结合水。
  EN · Moisture in wood—the original sap or water from other sources—exists as free water in cell cavities and bound water in cell walls.
• p.69 · 平衡含水率 · Equilibrium moisture content
  木材始终吸湿，在给定相对湿度下水分进出终达平衡。
  EN · Wood remains hygroscopic; at a given RH level, a balance of moisture exchange is eventually reached.
• p.71 · 生材、气干材与窑干材 · Green vs. air-dried vs. kiln-dried
  阔叶树初始含水率一般在 60%–100%，白蜡偏低；干燥状态分生材、气干、窑干三种。
  EN · Initial moisture contents in hardwoods generally run 60%–100%; green, air-dried and kiln-dried states are elaborated.
• p.73 · 木材的尺寸变化 · Dimensional change in wood
  干缩湿涨源于细胞壁结合水的得失，通常按弦、径、纵三个方向分别度量。
  EN · Shrinkage and swelling result from loss or gain of bound water, measured in the tangential, radial and longitudinal directions.
• p.76 · 估算干缩与湿胀 · Estimating shrinkage and swelling
  以典型实例说明如何定量估算木材的尺寸变化。
  EN · Typical examples consider dimensional change from a quantitative point of view.
• p.80 · 不均匀干缩与湿胀 · Uneven shrinkage and swelling
  翘曲等变形源于不同方向收缩率差异或整块木材内收缩不均。
  EN · Warp usually results from variable shrinkage in different directions or from uneven shrinkage within a piece.

第5章 · 应对木材胀缩 · CHAPTER 5 · Coping with Wood Movement …… 87

• p.91 · 监测水分 · Monitoring moisture
  正如「人人谈论天气，却无人有所行动」，许多木工会背含水率数字却疏于实测。
  EN · Many woodworkers recite intelligent-sounding numbers about moisture content yet neglect to actually monitor it.
• p.94 · 水分「小装置」 · The moisture “widgit”
  一个自制小装置：横杆一端悬挂试材，随时提醒关注含水率。
  EN · A simple gadget—a horizontal wand with a wood sample suspended from one end—reminds you about moisture content.
• p.95 · 木材如何干燥 · How wood dries
  干燥是木材水分关系中最重要、也最棘手的课题。
  EN · Drying is the most important and perhaps the trickiest subject of wood-moisture relationships.
• p.98 · 干燥窑 · The dry kiln
  典型干燥窑是带强制循环、控温控湿的隔热大室，材堆居中。
  EN · A typical dry kiln is a well-insulated chamber with controlled air circulation, temperature and humidity.
• p.99 · 自己干燥木材 · Drying your own wood
  小批量自干同样遵循锯切、堆垛、控速与监测的原则。
  EN · The same guidelines apply to drying small quantities: proper cutting, preparation, stacking, rate control and monitoring.
• p.104 · 存放锯材 · Storing lumber
  干材以聚乙烯膜或厚牛皮纸包裹，可安然度过极端干湿期。
  EN · Wrapping dry lumber in polyethylene film or heavy kraft paper helps through peak periods of dryness or humidity.

第6章 · 木材的强度 · CHAPTER 6 · Strength of Wood …… 107

• p.112 · 顺纹受压 · Compression parallel to the grain
  顺纹受压见于廊柱等承压构件，ASTM 标准试件长 8 英寸。
  EN · Stress that shortens fibers lengthwise, as in a column supporting a porch; the ASTM specimen is 8 in. long.
• p.113 · 横纹受压 · Compression perpendicular to the grain
  重物压桌面、压地板时木材承受的即横纹受压。
  EN · Heavy objects resting on a table or floor apply loads that stress wood in compression perpendicular to the grain.
• p.116 · 横纹受拉 · Tension perpendicular to the grain
  劈柴、钉钉、压平翘曲板都会遭遇木材横纹抗拉的薄弱。
  EN · Perpendicular-to-grain tensile failures occur when splitting firewood, driving nails or forcing cupped boards flat.
• p.118 · 顺纹受拉 · Tension parallel to the grain
  木材顺纹抗拉最强，但端部夹持处往往先破坏，这一优势难以利用。
  EN · Wood is strongest in tension parallel to the grain, but end fastenings usually split before the wood fails.
• p.118 · 横纹受剪 · Shear perpendicular to the grain
  细胞排列使木材极抗横纹剪切，厚材下只会压碎或撕裂，故无标准试验。
  EN · Wood is extremely resistant to shearing perpendicular to the grain; at appreciable thickness it crushes or tears.
• p.119 · 顺纹受剪 · Shear parallel to the grain
  紧固件或互锁榫「剪出」至端面即顺纹受剪失效。
  EN · Along the grain, wood separates in shear more readily—fasteners or interlocking joints shear out to the nearest end-grain surface.
• p.121 · 弯曲理论 · Bending theory
  树木天生是柱与梁的组合，木材受弯效率极高。
  EN · The tree evolved as a combination column and beam; wood is beautifully efficient when loaded in bending.
• p.124 · 梁的刚度 · The stiffness of beams
  重组弯曲应力与弹性模量两个公式，可深入理解受弯木构件的行为。
  EN · Rearranging the two formulas for bending stress and modulus of elasticity gives insight into beams.
• p.128 · 影响强度性能的因素 · Factors affecting strength properties
  除平均强度值外，还需考虑变异、缺陷、含水率与持荷时间。
  EN · Beyond average test values, variability, defects, moisture content and time under load all affect strength.
• p.133 · 压缩破坏 · Compression failures
  风暴或伐倒时树干过度弯曲，可在凹面形成不被察觉的压缩损伤。
  EN · Excessive bending in storms or felling can cause unnoticed compression damage on the concave side of the bole.
• p.134 · 结构材等级 · Structural grades
  无缺陷材与实际结构材性能差距巨大，故须建立允许应力等级体系。
  EN · Allowable stress ratings have been established because few pieces of structural lumber match defect-free test values.

第7章 · 其他性能 · CHAPTER 7 · Other Properties …… 137

• p.137 · 导热性 · Thermal conductivity
  木材的相对不导热性是大家熟悉的特性。
  EN · The relative thermal non-conductivity of wood is familiar to all.
• p.138 · 温度对木材的影响 · Effect of temperature on wood
  木材热胀冷缩极小，顺纹方向每温升一度仅约百万分之二。
  EN · Wood expands when heated and contracts when cooled; along the grain it changes only about 2 millionths per degree.
• p.138 · 木材的燃烧 · Burning of wood
  燃烧效率取决于炉具效率与木材含水率，按气干材热值估算。
  EN · Burning efficiency depends on stove efficiency and the moisture content of the wood.
• p.139 · 荧光 · Fluorescence
  黑光下某些木材发出神秘荧光，足以激发木工创作灵感。
  EN · Certain woods viewed under black light emit a mysterious glow, inspiring ideas in woodcraft.
• p.142 · 心理特性 · Psychological properties
  除标准化单位表达的物理性能外，木材给人的主观感受也是其「性能」。
  EN · Beyond properties expressed in standardized units, wood’s subjective feel is also one of its properties.

第8章 · 木材切削加工 · CHAPTER 8 · Machining Wood …… 145

• p.146 · 工件 · The workpiece
  三维结构、密度差异、纹理不均与心材抽提物都影响切削效果。
  EN · Three-dimensional structure, density variation, uneven grain and heartwood extractives affect machining.
• p.146 · 刀具 · The tool
  切削刃由刀面与刀背相交形成，其几何以前角、楔角等角度定义。
  EN · The cutting edge is formed by intersecting face and back surfaces, defined by rake and wedge angles.
• p.147 · 切屑形成 · Chip formation
  能量消耗于分离木材、使切屑变形及克服刀面摩擦。
  EN · Energy is consumed in severing the wood, deforming the chip and overcoming friction.
• p.148 · 切削作用类型 · Types of cutting action
  两种基本类型：刃口大致垂直于运动方向的正交切削，以及非正交切削。
  EN · There are two basic types of cutting action: orthogonal and non-orthogonal cutting.
• p.149 · 90°–0° 切削（顺纹刨削） · 90°–0° cutting (planing along the grain)
  手刨顺纹刨削是典型：刃口分离纤维起屑，切屑如悬臂梁受阻弯曲。
  EN · Parallel-to-grain cutting is best typified by the standard hand plane; the chip forms in a cyclic sequence of events.
• p.152 · 周边铣削（机械刨削） · Peripheral milling (machine planing)
  平刨、压刨、压簧轴刨与修边机的圆周刃切削即 90°–0° 正交切削的对应形式。
  EN · Peripheral milling on the jointer, surfacer, shaper and router is the counterpart of 90°–0° orthogonal cutting.
• p.155 · 90°–90° 切削（端面刨削） · 90°–90° cutting (planing end grain)
  端面刨削须横切纵向细胞，切屑靠剪切变形与破坏排出。
  EN · Planing across the end grain severs longitudinal cell structure; the chip moves largely by shear deformation.
• p.156 · 0°–90° 切削（横纹刨削） · 0°–90° cutting (planing across the grain)
  横纹刨削的经典是旋切单板——切屑本身就是产品。
  EN · The classic 0°–90° case is veneer cutting, where the chip itself is as important as the workpiece.
• p.157 · 横截锯切 · Crosscut sawing
  用顺齿锯横截效果不佳，横锯齿刃才能横割纤维形成切屑。
  EN · Sawing across the grain with a ripsaw is seldom satisfactory; crosscut teeth sever the fibers.
• p.160 · 组合与折中 · Combination and compromise
  不少工具兼有不同切削模式，或介于两种模式之间的折中。
  EN · Many tools involve a combination of cutting modes or a compromise between two types.
• p.161 · 磨刀 · Sharpening
  「锋利」包含刃口状态及其保持性两个层面。
  EN · Sharpness includes the condition of the cutting edge and how well it is maintained.

第9章 · 木材接合 · CHAPTER 9 · Joining Wood …… 165

• p.165 · 接合的要素 · The elements of joints
  单件木制品屈指可数，多数器物都由多块木材接合、紧固或胶合而成。
  EN · Few things are single pieces of wood; most products are joined, held or stuck together.
• p.166 · 接合的基本类型 · Basic types of joints
  按纤维取向与紧固方式，接合可分为咬合、紧固与胶合三类。
  EN · Joints are characterized by grain orientation and fall into worked, fastened and glued types.
• p.167 · 互锁接合 · Worked joints
  制作咬合互锁的形状以增强接合，是木工传统的核心骄傲。
  EN · Creating interfitting or interlocking shapes has been a hallmark of the woodworking tradition.
• p.169 · 燕尾榫接合 · Dovetail joints
  燕尾榫是木工传统最具象征意义的接合，牢固而优美。
  EN · Nothing is more symbolic of the woodworking tradition than the dovetail joint.
• p.170 · 斜接接合 · Miter joints
  平行纤维斜接高效美观；纤维 90° 相交的斜接则易因含水率变化开裂。
  EN · Parallel side-grain miters make an efficient corner; right-angle miters may open with moisture change.
• p.170 · 圆棒榫接合 · Doweled joints
  圆棒榫可作榫头、销钉与上胶辅件三类用途。
  EN · Dowels fall into three categories: as tenons, as pins and as gluing accessories.
• p.172 · 紧固件接合 · Fastened joints
  紧固件泛指钉、螺钉等以机械方式连接两件的「第三方」。
  EN · A fastener holds together two members, typically nails and screws.
• p.174 · 钉子 · Nails
  钉入端材的握持力最低可至侧材一半，但可预钻孔并加大钉径、长度或数量补偿。
  EN · End-grain holding power may be as little as half of side-grain, compensable by preboring and larger nails.
• p.175 · 木螺钉 · Woodscrews
  正确安装的木螺钉握持力超群，关键在于为螺纹段与柄预钻导向孔。
  EN · Correctly installed woodscrews have superior holding power; preboring pilot holes is the key.
• p.176 · 胶合接合 · Adhesive joints
  胶合使用史前即已开始，近代胶合板工业推动了胶黏剂的飞速发展。
  EN · Adhesive use predates recorded history; the plywood industry initiated modern adhesive development.

第10章 · 木材涂装 · CHAPTER 10 · Finishing Wood …… 181

• p.181 · 表面状态 · Surface condition
  涂装前须从物理与化学两方面考量表面状态。
  EN · Surface quality should be considered from the physical and the chemical standpoint.
• p.185 · 不处理 · No treatment
  完全不上涂装奏效的场合少而又少，但传统常迫使人们在成品表面涂涂刷刷。
  EN · Instances where no finishing treatment makes sense are few and far between, yet tradition forces finishes onto surfaces.
• p.187 · 涂层处理 · Coating treatments
  最通用的涂装是表面透明涂层；清漆特指树脂溶于油性溶剂的干性涂料。
  EN · The most universally used finishes are transparent coatings; varnish refers to tough resins dissolved in oil-based solvents.
• p.188 · 渗透型涂装 · Penetrating finish
  油饰与渗透型树脂油饰渗入木材而非成膜于表面。
  EN · Oil finishes and penetrating resin-oil finishes are in the wood, not on the surface.
• p.188 · 组合与折中 · Combinations and compromise
  作者爱做实验，如以亚麻油、醇酸清漆与松节油调配混合涂装。
  EN · A good starting point for amalgamating finishes is boiled linseed oil, alkyd varnish and turpentine.
• p.189 · 减缓水分交换 · Slowing moisture exchange
  没有涂装能完全隔绝水分，其作用是减缓交换速率以缓冲短时极端。
  EN · No finish is totally effective; its role is to retard the rate of moisture exchange enough to buffer extremes.
• p.189 · 表面评估 · Evaluation of surfaces
  低角度观察线条在表面的反射，是评估涂装质量的有效方法。
  EN · Observing line patterns reflected at low angles across a surface evaluates finished-surface quality.

第11章 · 木材改性 · CHAPTER 11 · Modifying Wood …… 191

• p.191 · 木材防腐处理 · Preservative treatment of wood
  含水率长期高于 20% 的用材场所，真菌与白蚁将不请自来，须防腐处理。
  EN · Where moisture can range above 20%, wood-inhabiting fungi will probably take up residence; preservatives are needed.
• p.193 · 稳定化处理 · Stabilization treatment
  以防尺寸变化为目标的化学处理，如木塑复合（WPC）浸注。
  EN · Stabilization processes prevent moisture-caused dimensional change, e.g., wood-plastic composite impregnation.
• p.198 · 实木弯曲 · Bending solid wood
  弯曲既省料又使纹理顺应曲线而更强，是木工的古老技艺。
  EN · Bending saves wood, reorients grain to the curving axis and yields greater strength—among the ancient arts.
• p.201 · 氨塑化 · Plasticizing with ammonia
  氨处理比蒸汽更有效，因它与木质素及纤维素均起作用。
  EN · Ammonia treatment is more effective than steaming, interacting with lignin as well as the cellulosic structure.

第12章 · 木工的原材料 · CHAPTER 12 · The Woodworker’s Raw Materials …… 203

• p.203 · 寻找木材 · The search for wood
  木工从何种形态的木材开始？因工艺而异，多数从已部分锯制的锯材开始。
  EN · With what form of wood does woodworking begin? Most crafts begin with lumber already partly converted.
• p.206 · 寻找商业来源 · Finding commercial sources
  从面向家具厂的批发商到按板英尺零售，木材来源多种多样。
  EN · Sources range from wholesalers selling to volume users to retail by the board foot.
• p.207 · 锯材 · Lumber
  锯材是锯、刨作业的产物，不再作进一步加工。
  EN · Lumber is the product of the saw and planing mill, not further manufactured.
• p.210 · 锯材计量 · Lumber measure
  锯材按名义尺寸以板英尺计量，软料规格取英寸整数倍。
  EN · Lumber is sold by volume in board feet according to nominal size; softwood sizes are in inch multiples.
• p.211 · 锯材分类与分级 · Lumber classification and grading
  按用途、加工度与尺寸分类，各级之下再行分级。
  EN · Lumber is classified by use, degree of manufacture and size; grades apply within each level.
• p.216 · 单板 · Veneer
  单板是纹理平行于表面的薄木层，家具与胶合板常用。
  EN · Veneer is wood in the form of a thin layer with grain parallel to the surface.
• p.220 · 胶合板 · Plywood
  奇数层薄木正交胶合，使整板性能趋于均一。
  EN · Plywood is an odd number of thin layers glued with adjacent grains perpendicular, equalizing properties.
• p.221 · 软木胶合板 · Softwood plywood
  软木胶合板工业以花旗松胶合板为起点，APA 制定了分级规则与制造标准。
  EN · The industry grew around Douglas fir plywood; the APA developed grading rules and manufacturing standards.
• p.223 · 硬木胶合板 · Hardwood plywood
  硬木胶合板专为展现面板美观而生，面板树种按比重分三类。
  EN · Hardwood plywood is made to display face veneers; face species are separated by specific gravity.
• p.224 · 复合木质材料 · Composite wood materials
  现代木材使用的明显趋势是从实木走向重组与复合材料。
  EN · The dominant trend is the shift from solid wood to reconstituted or composite wood products.
• p.224 · 刨花板 · Particle board
  颗粒随机分布使刨花板各向性能均一、尺寸稳定。
  EN · Random particle distribution gives particle board uniform properties and reduced dimensional change.
• p.227 · 硬质纤维板 · Hardboard
  热压而成的纤维板，1924 年由 Masonite 公司始创，「Masonite」几成通用名。
  EN · Hardboard is interfelted fiberboard consolidated under heat and pressure; “Masonite” is used generically.

第13章 · 后记：森林的过去与未来 · CHAPTER 13 · Afterword: Forests Past and Future …… 229

• p.230 · 木材会够用吗？ · Will there be enough wood?
  尽管有「木材饥荒」的可怕预言，作者对森林经营与复合材料技术持乐观态度。
  EN · Despite alarming forecasts of timber famine, the author remains optimistic about forests and composite technology.

附录 1 · 锯材商品名 · APPENDIX 1 · Commercial names for lumber …… 233

附录 2 · 测定木材比重 · APPENDIX 2 · Finding the specific gravity of wood …… 236

术语表 · Glossary …… 238

参考书目 · Bibliography …… 248

索引 · Index …… 251