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Lumber Characteristics & Defects

Lumber Characteristics & Defects


Our sawyer here at The Lumber Shack has an exceptional eye for detail when selecting the lumber logs used to saw quality lumber slabs that are sure to catch your eye.  The term live edge, also known as natural edge is a style of furniture where the builder incorporates the natural edge of the wood into the design of the piece.   By using this technique to build strong, natural and unique pieces of furniture, there are some characteristics in our pieces that may be considered defects to some, however, we consider a lot of them to be highlights on most of the lumber slabs and pre-finished furniture we have to offer.  These characteristics are both the natural growth characteristics and manufacturing imperfections of a piece of wood.  Some characteristics are important in evaluation of strength, others may be of minor importance to strength, but very significant to appearance.  Below is a list of some of these features:

wood characteristicsKnots:

One of the most obvious lumber characteristics.  A knot is a portion of a branch or a limb that has become incorporated in a piece of lumber.   The knots described in our lumber are generally sound knots, unsound knots and knot holes.
Sound Knots are solid across the surface, at least as hard as the surrounding wood, and shows no indication of decay.
Unsound Knots have cracks or void or is noticeably softer than the surrounding wood.
A knot hole is a knot that has fallen out, leaving a hole.wood defects

wood knots


lumber wood characteristicsWane:

The presence of bark or the lack of wood fiber along the edge of a piece of lumber.  Bark may be present, or part of the edge may be missing.


lumber defectWorm Hole:

Any hole made by boring insects or their larvae.

planer snipe lumber wood defectPlaner Snipe:

The planer "snipe" attribute is defined when a planer cuts a little bit deeper at the beginning or end of a long board.The planer snipe effect is usually quite subtle, but if you run your fingers along the board, you can usually feel a slight step. Shining a light on the board at a low angle also reveals it.  

For small thickness planers, snipe is primarily caused by movement of the cutter head assembly. I constructed a simple wooden model to illustrate what happens.

As the board exits the planer, the infeed roller runs off the end of the board. The rubber rollers apply quite a bit of downward pressure to the board, and as the roller rolls off the board, there is a lot less upward pressure against the head assembly from the roller, so the whole head assembly typically moves down a tiny bit.

wood lumber defectsPith:

The soft textured tissue located in the very center of a cross section of tree trunk, branch or twig.  The pith in hardwoods is sometimes a cavity (open) while the pith in softwoods is usually sound.


shake wood defectShake:

The separation of wood along an annual growth ring..

Bark Inclusion or Bark Pocket:

An isolated area in wood, largely made up of bark that has grown into the sapwood of a tree.  This can be caused by irregular growth or due to damage to a tree.  The bark area is frequently completely overgrown over time by new growth and thus seems to exist magically inside the tree with no link to the outer bark.
metal wood defectMetal:

When any type of metal, whether it be a nail that was driven into the tree from someone hanging a bird feeder, or even one of those funny faces that people hang on trees, or when a tree grows through a barbed wire fence, or even when someone shoots a tree with bbs, in most cases the tree is not going to care, it will keep growing, creating a pocket or wound over the metal, until the tree completely engulfs the piece of metal.  When this happens, the wood will get blue staining, depending on how long the tree continues to grow, the staining will generally go from the metal down to the ground, it doesn’t go up the tree.  It makes for some very interesting slabs when we get the opportunity to cut through a piece of this metal.  The saw hates it, and it ALWAYS ruins a chain, but we have had some interesting pieces from this.  We even have a picture of a slab with an insulator that was cut in half, and is still embedded in the tree.  Sometimes the nails/metal is still in the slab, sometimes we are able to pull it out before we cut the logs, but almost always it leaves a blue staining.

Bird Peck:

Birds peck on trees primarily to cause panic to the little insects that are eating away at the phloem.  This causes the insects to come out and the birds then eat them.  Bird pecking can cause small injuries to the tree that result in grain changes that later show up as various forms of figure in the wood.bird beck wood character


punky wood defectPunky:

A condition of wood in which it is very soft and light with very low density.  Punky wood can be either a natural condition, like in the pith at the heart of the tree, or it can be the result of rot.  Stabilizers can be used to allow somewhat punky wood to be used in its natural form in projects.  Wood that has started to spalt will turn punky if not caught soon enough in the spalting process.


spalted slabs wood defectSpalt:

Dead wood that has undergone a particular form of bacterial decay that often looks like a black ink line of varying thickness and great irregularity drawn through the wood.  When it is very sharply defined black lines it is sometimes called “black line spalting”.  Wood that is really heavily spalted and still completely solid is rare, but something we specialize in.  Spalted wood that has soft areas but is not too far gone into the process of rotting can often still be used in craft projects by treating the wood with a stabilizer.



Any deviation from a true or flat surface.