astlöcher

Astlöcher, in wood terminology, are cavities that form where a branch was once connected to the trunk. They appear as holes or voids at branch attachment points and can extend into sapwood or heartwood. Astlöcher are a common type of wood defect and are often found in softwood timber, especially near branch junctions.

Causes and appearance

Astlöcher arise when branches die, are removed, or break away, leaving a hollow or empty space in the trunk. The hole may be circular or oval and can be accompanied by discoloration around the surrounding wood. In some cases the hole is partly filled with resin or callus tissue as the tree attempts to seal the scar.

Impact on properties

Astlöcher reduce the local strength of the wood and create stress concentrations, which can complicate machining, planning, and finishing. They can also increase porosity and moisture ingress, potentially affecting durability and dimensional stability. The presence, size, and location of astlöcher influence lumber grading and suitability for structural or decorative applications.

Assessment and remediation

In lumber grading, the size and position of astlöcher contribute to the overall quality score. For existing pieces, astlöcher can be addressed by filling with epoxy or wood filler, dowelling, or grafting/reinforcement in some cases. In rustic or reclaimed wood, such holes may be retained for aesthetic value and character.

See also

Knots, knotholes, wood defects, lumber grading.