The types of defects in timber are divided into the following parts.

1. fault due to conversion

The following defects may occur during the process of commercially converting timber.

  • Chip Mark: chip mark
  • Diagonal Grain: due to improper cutting of wood
  • Cracked Grain: Small impressions are made by the fall of the tool
  • Useless: Original rounded surface appearance on a manufactured piece of wood

2. defect caused by fungus

When the moisture content of wood is more than 20% and there is presence of air and heat for the growth of fungus then attack of wood by fungus causes the following defects

  • Blue Stain: wood sap is painted blue
  • Brown rot: The removal of cellulose compounds from wood and wood causes wood rot or disease to turn brown
  • dry rot: convert wood into dry powder
  • Heartburn: It is formed when a branch comes out of a tree and the tree becomes weak and a soft sound is produced when struck with a hammer.
  • Juice stain: Sap wood loses its color as the sap feeds on the cell contents of the wood.
  • wet rot: The chemical decomposition of wood and wood causes it to turn into a brownish brown powder known as wet rot.
  • white rot: The attack of wood and wood takes the form of a lignin white mass.

3. defects caused by insects

  • Beetle Cars: Small insects make holes in size about 2 mm in diameter and attack the sap wood of all hardwood species. The larvae of these beetles build tunnels in all directions in the sapwood and are ground into a fine powder like powder. They don’t distract the outer shell and look sound.
  • sea ​​borer: They make holes or bore tunnels in the wood to take shelter. Wood attacked by sea borers loses color and strength
  • Termite: White ants are very quick to eat the wood away from the core of the cross section. They tunnel in different directions and usually do not disturb the outer shell or cover.

4. defects caused by natural forces

The main natural force responsible for causing defects in wood is abnormal growth and buoyancy of tissues.

  • burleso: Irregular projections appear on the wooden body due to shock at an early age
  • callus: The soft tissue or skin that covers the wound of the tree.
  • chemical stain: discolored due to chemical action
  • Fat grain: The annual ring becomes wider, the tree grows faster so the wood has less strength
  • dead wood: timber obtained from dead standing trees
  • Intoxication: white rotten spots by fungus
  • gluttony: due to the onset of decay due to poor ventilation during storage or due to over maturity indicated by red or yellow color in the wood
  • nautical mile: The bases of branches or limbs which are broken or cut from the tree as shown in fig-1.
fig-1 knot
  • rind glass: Chhilka means bark and pitta indicates abnormal growth and peculiar curved swellings found on the body of a tree.
  • shakes: These are cracks which separate the wood fibers partially or completely as shown in fig-2.
Fig – 2 different types of shakes
  • twisted fiber/wdear heart: Due to twisting of young trees due to strong wind gusts as shown in fig-3.
fig-3 twisted fibers
  • upset or broken: Indicate the wood fibers which have been injured by crushing or compression as shown in Fig.-4.
fig-4 upset

Read also: 10 Most Important Qualities of Good Timber

Read also: How to classify timber on the basis of grading?

Read also: What is Timber Spice?

Read also: How to store timber at construction site?

Er. Mukesh Kumar

Photo of author
Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.