What Are the Different Types of Defects in Timber?

different types of defects in timber

Defects in timber are a very natural thing and can happen for many reasons such as natural forces, calamity, environment, insects, fungi, seasoning, etc. Having a brief knowledge of the different types of timber defects can help you easily identify a defect so that it can be dealt with properly and on time. Timber defects when not handled on time can lead to serious damage to your timber, making it unusable or reducing its lifespan.

CameroonTimberExportSarl is a top provider & exporter of high-quality wood timber in 50+ species and at the best price with doorstep delivery to all major countries around the globe. Our timbers are locally-produced, quality-tested and defect-free.

Different types of timber defects occur at different stages during the production and processing of timber. Let’s talk about the different types of natural defects in timber caused due to things such as natural forces, insects, fungi, seasoning and timber conversion.

5 Major Timber Defects In Detail

1. Types of Timber Defects Caused by Natural Forces

A large number of timber defects might occur due to natural forces, including wind cracks, shakes, upsets, burls, chemical stains, twisted fibers, water stains, knots and more.

  • Wind cracks occur when the outer surface starts shrinking and cracks are formed on the timber surface due to constant exposure to high-speed winds.
  • Shakes are cracks in the wood that might occur due to a variety of reasons such as non-uniform growth of wood or bending due to natural causes. Common types of timber shakes include cup shakes, heart shakes, ring shakes, star shakes and radial shakes.
  • Twist Fibers occur when the fibers in a timber tree are twisted due to external sources like high-speed winds.
  • Upsets are another type of timber defect that occur when the wood fibers are crushed due to external forces like high-winds or improper chopping.
  • Rind Galls refer to when trees start curved swelling, which generally happens due to inappropriate removal of a tree branch.
  • Burlsare uneven shapes that occur on the body of the tree due to specific injuries including shocks occurring during its growth.
  • Water stains are stains caused due to constant contact of wood with water which results in a permanent stain occurring on the wood surface.
  • Chemical Stains occur when the wood starts reacting with external chemicals like gases present in the atmosphere.
  • Dead wood is the wood that is extracted from a dead tree. It is very light and has poor strength and durability.
  • Timber knots occur after conversion of timber on places where a branch has been removed and a mark has been left as a result.
  • Coarse grain is when the gap between the annual rings is unusually large in fast-growing trees.
  • Druxiness is a type of defect in which the timber surface starts showing white spots and may lead to fungi problems.
  • Callus is the soft skin that covers the wound of a tree.

2. Variety of Wood Defects Caused Due to Fungi

Fungi in timber can lead to a variety of defects in the wood, which may include dry rot, wet rot, white rot, brown rot, heart rot, blue stain and sap stain.

  • Dry rot is when the wood is being eaten by a specific type of fungi, which converts it to a dry powder form. This happens when the wood has been improperly seasoned.
  • Wet rot occurs when the wood is put through alternate dry and wet conditions and fungi starts growing on it.
  • Brown rot is when the timber color turns brownish because a specific type of fungi has been eating its cellulose compounds.
  • White rot occurs when the timber color turns white because these types of fungi eat the timber lignin.
  • Blue stain is a type of defect which is caused by a specific type of fungi that turns the wood blue.
  • Heart rot occurs when fungi eat up the heartwood of a tree, usually through a newly grown branch.
  • Sap stain occurs when a type of fungi makes the sapwood discolored. This generally happens in timber with 25% or higher moisture content.

3. Types of Timber/Wood Defects Caused During Seasoning

Seasoning is the process of drying timber to reduce moisture content without causing physical damage to the wood. Inappropriate seasoning can lead to a number of defects, such as bow, cup, check, split, twist, warp, collapse and others.

  • Bow is when timber planks start forming a curve shape when stored for a long period after seasoning.
  • Cupping of timber refers to the timber having a curve along its width.
  • Sometimes due to over seasoning of timber, the wood fibers start separating, causing cracks in the wood, which are called checks
  • When checks spread to either end of the timber, it results in the wood splitting into two or more parts.
  • Twistis when the timber has a spiral curve along its length.
  • Honeycombing in timber occurs due to stresses created during the seasoning process.
  • When the top surface of wood dries rapidly than the inner part during seasoning, a type of defect is formed that is called case hardening
  • Collapse is the wood defect that occurs due to improper drying shrinkage of wood caused due to uneven drying of different parts.

4. Types of Timber Defects Caused by Insects

Insects are one of the primary reasons to destroy the quality and reduce the lifespan of timber. While some woods are resistant to insect attack, others are not and may need to be treated externally.

Termites, beetles and marine borers are three of the most common types of insect responsible for timber damage. Termites are white ants that eat up the timber from the inside without harming the outer layer. Beetles are small insects that affect the sapwood of the timber, converting it into power form. Marine borers live inside the timber by making large holes up to 60mm.

5. Major Wood Defects Caused During Conversion

Conversion is the process of turning wood logs into timber or lumber that is ready to use. A variety of defects can occur during the timber conversion process. The most common ones include diagonal grain, torn grain, chip mark and wane.

To know more about our timber seasoning and conversion process and how we ensure minimal defects on timber, contact CameroonTimberExportSarl.