Shop Materials Safety Reading Wood And Stock

---
name: shop-materials-safety-reading-wood-and-stock
description: "Use before cutting anything: how wood and metal differ in ways that change every technique downstream, shop safety and the practices that actually prevent injuries, reading wood including grain, figure, moisture content and movement, and stock selection and preparation from rough lumber to flat, square and ready. Includes the router for the whole wood and metal shop reference."
---

# Wood and Metal Shop Craft: The Two Materials Compared, Shop Safety, Reading Wood, and Stock Selection and Preparation

> **Part 1 of 5** of the *Working with Wood and Metal* reference (plugin `working-with-wood-and-metal`), covering §0–§4. Sibling skills: `shop-woodworking-tools-sharpening-joinery-and-finishing` (§5–§12), `shop-metalwork-cutting-drilling-and-machining` (§13–§18), `shop-welding-forging-heat-treatment-and-shop-setup` (§19–§26), `shop-reference` (§27–§32). Section numbers are shared across the set; a reference written as §N → `skill` points into that sibling skill.
>
> **Currency:** The craft is centuries old. Two areas moved. See §27 → `shop-reference` for US table saw safety regulation, and welding fume exposure control.

> **⚠️ Two materials that punish opposite mistakes.** ⚠️ **Wood MOVES forever and forgives
> imprecision; metal is dimensionally stable and forgives nothing.** **⚠️ Wood is worked
> with the grain and cut fast; metal is worked against resistance and cut slowly.**
> **The habits that make you good at one will actively hurt you at the other.**
>
> **Complements a manufacturing reference (industrial process and tolerancing), a
> materials/furniture reference (wood movement and finishing at the design level), and a
> thermodynamics reference (heat treatment physics).**
>
> **⚠️ SAFETY IS §2 AND IT IS FIRST FOR A REASON.** ⚠️ **This document describes techniques;
> it does not substitute for supervised instruction on machinery. The table saw, angle
> grinder and welding arc each injure large numbers of people every year, and the
> mechanisms are specific and learnable.**
>
> **⚠️ GOTCHA** boxes mark the habits that cause injuries and the received wisdom that's
> wrong.
>
> **The three ideas that organize this document:**
> 1. **⚠️ SHARP IS SAFE** (§7 → `shop-woodworking-tools-sharpening-joinery-and-finishing`). **A dull tool requires force, force removes control, and
>    loss of control is how people get hurt. Sharpening is not a side skill — it's the
>    gateway to everything else.**
> 2. **⚠️ The material is not neutral** (§3, §14 → `shop-metalwork-cutting-drilling-and-machining`). **Wood grain direction, and metal's
>    heat and work-hardening behaviour, determine technique. Fighting the material is
>    the definition of doing it wrong.**
> 3. **⚠️ The invisible hazards are the ones that get you** (§2, §26 → `shop-welding-forging-heat-treatment-and-shop-setup`, §27.2 → `shop-reference`). **Wood dust
>    and welding fume are classified carcinogens with no warning symptoms — and they're
>    the risks hobbyists systematically ignore in favour of the dramatic ones.**

---

## §0. Routing

| You want... | Go to |
|---|---|
| Comparing the two materials | §1 |
| **⚠️ SAFETY** | **§2** |
| Reading wood | §3 |
| Stock selection | §4 |
| Layout and marking | §5 → `shop-woodworking-tools-sharpening-joinery-and-finishing` |
| **Hand tools (wood)** | **§6 → `shop-woodworking-tools-sharpening-joinery-and-finishing`** |
| **⚠️ Sharpening** | **§7 → `shop-woodworking-tools-sharpening-joinery-and-finishing`** |
| Machines | §8 → `shop-woodworking-tools-sharpening-joinery-and-finishing` |
| **⚠️ Table saw specifically** | **§9 → `shop-woodworking-tools-sharpening-joinery-and-finishing`** |
| Joinery technique | §10 → `shop-woodworking-tools-sharpening-joinery-and-finishing` |
| Glue-ups | §11 → `shop-woodworking-tools-sharpening-joinery-and-finishing` |
| Wood finishing | §12 → `shop-woodworking-tools-sharpening-joinery-and-finishing` |
| **Metal for the shop** | **§13–§14 → `shop-metalwork-cutting-drilling-and-machining`** |
| Marking out metal | §15 → `shop-metalwork-cutting-drilling-and-machining` |
| Cutting metal | §16 → `shop-metalwork-cutting-drilling-and-machining` |
| Drilling and tapping | §17 → `shop-metalwork-cutting-drilling-and-machining` |
| Manual machining | §18 → `shop-metalwork-cutting-drilling-and-machining` |
| **⚠️ Welding processes** | **§19 → `shop-welding-forging-heat-treatment-and-shop-setup`** |
| Brazing and soldering | §20 → `shop-welding-forging-heat-treatment-and-shop-setup` |
| Forming and forging | §21 → `shop-welding-forging-heat-treatment-and-shop-setup` |
| Heat treatment | §22 → `shop-welding-forging-heat-treatment-and-shop-setup` |
| Metal finishing | §23 → `shop-welding-forging-heat-treatment-and-shop-setup` |
| Fasteners and fits | §24 → `shop-welding-forging-heat-treatment-and-shop-setup` |
| Measurement | §25 → `shop-welding-forging-heat-treatment-and-shop-setup` |
| **⚠️ Shop setup, dust and fume** | **§26 → `shop-welding-forging-heat-treatment-and-shop-setup`** |
| **What's live** | **§27 → `shop-reference`** |
| Misconceptions, numbers | §28–§29 → `shop-reference` |
| Learning, quick ref, method | §30–§32 → `shop-reference` |

---

## §1. The Two Materials Compared

```
                    WOOD                      METAL
STABILITY      ⚠️ moves with humidity      ⚠️ stable; moves with heat
DIRECTIONALITY ⚠️ ANISOTROPIC (grain)      mostly isotropic
CUTTING        fast, low force             ⚠️ slow, high force, heat
TOLERANCE      ⚠️ ±0.5 mm is often fine    ⚠️ ±0.02 mm is routine
JOINING        glue is stronger than wood  ⚠️ welding melts the parent
MISTAKES       ⚠️ often recoverable        ⚠️ removed metal never returns
HAZARD         ⚠️ dust, kickback, blades   ⚠️ fume, heat, sparks, swarf
```
**⚠️ The habit transfer that hurts**: ⚠️ **woodworkers coming to metal push too hard and too
fast and burn tools; metalworkers coming to wood ignore grain direction and tear out.**
**⚠️ In both, the fix is the same — let the tool cut at its own rate.**

---

## §2. ⚠️ Shop Safety

> **⚠️ Read this before anything else. The injuries in this domain are predictable and
> the mechanisms are specific.**
```
⚠️ THE ACUTE HAZARDS
   ⚠️ TABLE SAW KICKBACK and blade contact (§9) — ⚠️ the single most
      injurious woodworking machine
   ⚠️ ANGLE GRINDER — ⚠️ disc shatter, kickback, and the sparks it
      throws are burning metal that starts fires metres away
   ⚠️ ENTANGLEMENT — ⚠️ NO gloves near rotating machinery (lathes,
      drill presses); no loose sleeves, no jewellery, tie back hair.
      ⚠️ Gloves on a lathe is how people lose hands
   ⚠️ ARC EYE — ⚠️ UV burns the cornea, symptoms appear HOURS later,
      and BYSTANDERS are exposed too (§19)
   ⚠️ HOT METAL looks identical to cold metal
   ⚠️ SWARF and chips — ⚠️ never clear by hand; use a brush, machine off
⚠️ THE INVISIBLE HAZARDS — the ones people ignore
   ⚠️ WOOD DUST is a classified carcinogen (⚠️ hardwood dust
      particularly, associated with nasal and sinus cancers) and a
      respiratory sensitizer. ⚠️ The FINE fraction you can't see is
      the dangerous part
   ⚠️ WELDING FUME — ⚠️ IARC Group 1 carcinogen; hexavalent chromium
      from stainless is severely regulated (§27.2)
   ⚠️ GALVANIZED metal releases zinc oxide when heated — metal fume fever
   ⚠️ NOISE — cumulative and irreversible. ⚠️ Hearing protection every time
   ⚠️ SOLVENTS and finishes (see a materials reference on oily rags —
      ⚠️ linseed and tung oil rags SPONTANEOUSLY COMBUST)
⚠️ THE HIERARCHY (see a civil/industrial reference)
   ⚠️ ELIMINATE the hazardous operation > SUBSTITUTE a safer process >
   ENGINEERING CONTROLS (guards, extraction, riving knife) >
   ADMINISTRATIVE (procedure, training) > ⚠️ PPE LAST
   ⚠️ PPE is the WEAKEST control and it is what hobbyists reach for first
```
**⚠️ The habits that actually prevent injury**: ⚠️ **never reach over or behind a spinning
blade; use push sticks and hold-downs; unplug before changing blades or bits; keep the
floor clear; work at a pace that permits thinking; ⚠️ and stop when tired, because
fatigue-driven shortcuts are the common precondition to most shop injuries.**
**⚠️ Fire**: ⚠️ **have an extinguisher; understand that grinding sparks smoulder in sawdust
and rags for a long time before igniting; and never grind near flammables.**

---

# PART I — WOOD

## §3. Reading Wood

**⚠️ Wood is a directional, hygroscopic, biological material, and every technique follows
from that.**
```
⚠️ GRAIN DIRECTION governs everything. ⚠️ Planing "uphill" against
   the grain TEARS OUT; planing downhill cuts cleanly. ⚠️ Read the
   grain on the edge before you cut
⚠️ MOVEMENT  ⚠️ wood expands and contracts across the grain with
   humidity, FOREVER. Tangential movement is roughly 2× radial,
   which is why flatsawn cups and quartersawn stays flat
   ⚠️ Never fix a wide solid panel rigidly across its grain
⚠️ EARLYWOOD vs LATEWOOD  soft and hard bands; ⚠️ this is why ring-porous
   species like oak plane and finish differently from diffuse-porous
⚠️ FIGURE  curl, quilt, birdseye, crotch — ⚠️ beautiful and usually
   accompanied by wild grain that tears out under a plane
⚠️ DEFECTS  knots (⚠️ hard, and they deflect blades), checks, shakes,
   wane, ⚠️ REACTION WOOD (moves unpredictably — reject it)
```
**⚠️ Moisture content is the number that matters**: ⚠️ **acclimatize stock to the shop and
to the destination before working it; kiln-dried to roughly 6–8% for heated interiors.**
**⚠️ A cheap moisture meter prevents expensive failures.**
**⚠️ Hardwood vs softwood is a botanical distinction, not a hardness one** — ⚠️ **balsa is a
hardwood and yew is a softwood.** **Use the Janka scale for actual hardness.**

---

## §4. Stock Selection and Preparation

**⚠️ Board defects to check before buying**: ⚠️ **cup, bow, crook and TWIST — and twist is
the worst because it costs the most thickness to remove.**
**⚠️ Sawing patterns**: **flatsawn (cheap, wide figure, moves most), quartersawn (⚠️ stable,
ray fleck in oak, expensive), riftsawn.**
**⚠️ The four-square process is the foundation of accurate work:**
```
⚠️ 1. ONE FACE FLAT (jointer or hand plane)
⚠️ 2. ONE EDGE SQUARE to that face
⚠️ 3. SECOND FACE PARALLEL (thicknesser/planer)
⚠️ 4. SECOND EDGE PARALLEL (table saw)
⚠️ Everything downstream depends on this. Skipping it means every
   joint fights you
```
**⚠️ Sheet goods**: **plywood (⚠️ dimensionally stable — which is why casework uses it),
MDF (⚠️ flat and its dust is particularly fine and hazardous), particleboard, and veneered
panels.**