How Logs Become Boards

The moment a log becomes boards, you lock in grain, stability, and waste.

This guide explains the main sawing patterns and what they create in real timber: ring orientation, grain appearance, movement behaviour, and defect risk.

The Big Idea: Sawing Is About Ring Orientation

Inside every log are growth rings.

When you slice the log, you choose the angle those rings will sit in each board.

That ring orientation largely controls:

• grain appearance (cathedrals vs straight grain)
• how likely a board is to cup
• how consistently it machines

The same species, from the same log, can produce boards that behave very differently depending on how they were sawn.

Step 1: From Tree to Log (What Happens Before Sawing)

Before a saw ever touches the wood, choices already matter.

Bucking (cutting the trunk into lengths)

Logs are cut to length based on:

• the intended product length
• defects in the trunk
• taper and straightness

End sealing (to reduce checking)

Fresh logs lose moisture fastest from the ends.

That can cause end checks.

Many mills seal ends (wax, paint, commercial sealers) to slow end drying and reduce splitting.

Metal detection

Urban or farm trees can contain nails, wire, and staples.

Metal damages saw blades and can be dangerous.

Step 2: Debarking and Scanning

Most mills debark logs to:

• reduce grit and debris that dulls blades
• reduce contamination in downstream processes

Larger mills may scan logs to optimise cut patterns for yield and grade.

The Main Sawing Patterns

There are many variations, but most boards you buy come from one of these approaches.

Plain (Flat) Sawing

Plain sawing is the most common method.

The log is sliced through in a series of parallel cuts.

What it produces

• wide boards efficiently
• high yield
• strong cathedral grain on faces

Typical growth ring orientation in the board

• rings are often 0–30° to the face (arched on end grain)

Pros

• economical
• wide boards possible
• attractive figure in many species

Cons

• boards are more prone to cupping
• more variation across a single board (heartwood/sapwood, ring curvature)

Practical reading tip

On end grain, flat sawn boards show rings as strong arcs.

A common “cupping tendency” visual:

• boards often cup so the arcs try to flatten.

Quarter Sawing

Quarter sawing aims to produce boards where rings are closer to 60–90° to the face.

A traditional method is to quarter the log and then saw boards from each quarter.

What it produces

• straighter grain
• more consistent behaviour

Typical growth ring orientation

• rings are closer to vertical lines on end grain

Pros

• usually more stable across width
• less cupping
• more uniform face grain
• can reveal ray fleck in some hardwoods (especially oak)

Cons

• lower yield than plain sawing
• boards may be narrower
• can be more expensive

Rift Sawing

Rift sawing targets rings around 30–60° to the face (often aiming near 45°).

It is often used when you want very consistent straight grain, especially for legs.

Pros

• very consistent appearance
• very consistent movement behaviour

Cons

• lowest yield
• most waste
• expensive

Through-and-Through vs Cant Sawing (Common Mill Variations)

Through-and-through (a plain-sawing variation)

The log is sliced without turning, producing a mix of ring orientations across the stack.

• outer boards tend to be more flat sawn
• boards nearer the centre may be closer to quarter sawn

Cant sawing

The log is first squared into a cant, then boards are sawn from the cant.

This is common for structural timber production.

What the Centre of the Log Does to Boards (Pith and Juvenile Wood)

The pith

The pith is the very centre of the tree.

Boards containing pith are more likely to:

• crack
• twist
• cup

Juvenile wood

Wood formed in the early years of growth (near the centre) can have different properties:

• different shrinkage
• lower stiffness in some species
• more movement issues

This is one reason boards cut near the centre can misbehave even if they look “clean.”

Why Boards Warp After Sawing

Warp is often blamed on “bad wood”, but it is usually predictable.

Common causes include:

1. Growth stresses released

Trees contain internal stresses.

Sawing relieves them unevenly.

1. Moisture gradients

If the outside dries faster than the inside, boards can cup or bow.

1. Ring orientation

Flat sawn boards have more tangential movement across their width.

1. Grain runout and spiral grain

If fibres do not run straight, boards are more likely to twist.

1. Knots and fibre deviation

Knots disturb fibre direction and shrinkage patterns.

Choosing Boards by Reading the End Grain (A Buying Checklist)

When selecting boards, check:

• Ring orientation
  • flatter rings: more cupping potential
  • more vertical rings: usually more stable
• Presence of pith
  • avoid pith for most furniture parts
• Checks and shake
  • end grain is the easiest place to spot these
• Runout
  • look for grain lines diving out of the face
• Knots and knot clusters
  • assess how the grain flows around them

Structural Timber vs Furniture Timber (Same Process, Different Priorities)

Structural

Priorities:

• predictable strength
• grading rules
• straightness
• knot limits depending on grade

Furniture and joinery

Priorities:

• stability
• appearance
• machining behaviour
• defect placement and grain selection for parts

The saw pattern may be similar, but what counts as “good” changes with the job.

Media and Image Recommendations

These make the sawing concepts click quickly:

1. Diagram: log cross-section with board cuts
   • show plain sawn boards vs quarter sawn boards
   • label ring orientation in each board
2. End-grain photo set
   • one flat sawn end grain
   • one quarter sawn end grain
   • one rift sawn end grain
   • annotate likely movement direction
3. Face-grain photo set
   • cathedral grain vs straight grain
   • same species if possible
4. Short mill video clip (15–30 seconds)
   • a bandsaw slicing boards
   • or a cant being broken down
   • include a shot of the resulting stack
5. Defects close-ups
   • pith in a board
   • end checking
   • shake

Foundations Wrap-Up (What You Should Know After Guide 10)

If you have read the full Foundations track, you should now be able to:

• explain what wood is and how it forms
• understand the cellular structure behind wood behaviour
• read growth rings and the zones inside them
• recognise heartwood vs sapwood
• understand grain direction and end grain
• predict how sawing patterns influence stability

That is the baseline for everything that comes next.