The Secret Behind Spalted Wood
Some of Nature's Most Beautiful Designs

 

Spalted wood is wood that has been altered by competing fungi (mushrooms) for a limited amount of time, resulting in beautiful, naturally variegated, shifting hues and lines known as zone lines coveted by many woodworkers and designers.

The Science of Spalting Wood

When a tree dies or has otherwise been stressed, it becomes vulnerable to fungi ready to consume it. The fungi infiltrate the wood in waves of primary and secondary colonizers. The first wave captures and controls the wood’s resources even changing the pH of the wood and its structure. This first wave of invading fungi then has to defend against the second wave of colonizers. What we see as beautiful lines in the wood are actually boundaries drawn by different fungal colonies defending their territory. These fungal boundaries are the reason that there is no regular pattern or logic to designs, unlike features such as a tree’s growth rings.

Conditions for Spalting

For spalting to occur, certain conditions must exist for the fungi to flourish within the wood. Factors include the amount of water saturation, the temperature of the wood, the amount of oxygen present, and the amount of time the fungus has to paint its masterpiece. 

  • Water: For fungal colonization to occur, the wood should be above the fiber saturation moisture content. See “Oxygen” below for over-saturation. 

  • Temperature: Our fungi responsible for creating spalted wood are from robust Vermont stock and prefer a temperature range of 50-65d.F

  • Oxygen: Fungi require an appropriate level of oxygen. An overly waterlogged or submerged piece of wood will not grow fungus as it lacks sufficient oxygen. 

  • Time: Our proprietary blend of fungi requires approximately 24 months to complete the transformation from a chromatic homogeny, commodity product to a work of art. The trick to creating commercial grade spalted wood is to understand when to stop the progress of the decay so that the desired designs are visible while the strength and integrity of the wood remain intact.

Types of Spalting

Spalting is classified by three main facets: zone lines, white rot, and pigmentation. However, the way in which hardwoods (deciduous) and softwoods (coniferous) spalt and what types of fungi are present is often different.

  • Zone Lines: The signature visual characteristics of a spalted maple include inky winding lines, dark dotting, and thin streaks of red, brown and black. These natural design patterns are known as zone lines. These lines generally delineate where fungus are interacting and where they have erected mycelium barriers to protect their resources. Though fungi can damage wood, these zone lines themselves do not affect the structural integrity of the wood.

  • White Rot: Spalted Maple will often have streaks of lighter colors. This is due to white rot fungi which effectively bleaches the wood by consuming the pigmented area of a wood cell called lignin. Unlike zone lines, white rot spalting does cause a weakening of the wood, causing what woodworkers call punky areas in the wood and eventually rendering wood unusable if not controlled.

  • Pigmentation: There are often multiple shades and a variety of colors present in spalted maple. This is due to pigmentation, which is caused by fungi producing extracellular pigments inside wood. The fungi that cause pigmenting do destroy the integrity of the wood but at a slower rate than their white rot compatriots - this is called soft rotting.

While the natural environment can provide ideal conditions for spalting to occur, the variables are infinite. This is why serendipitously finding the fungal designs in a felled tree in the Vermont woods always holds such anticipation.

Even in the most controlled environments, spalting takes on a life of its own and one can never know which way the fungal battles will go. For this very reason, no commercial scale veneer or plywood mill has ever been able to offer spalted wood veneer and plywood to the industry.

At Vermont Wildwoods we have developed a process to intentionally create spalting through the controlled release of fungi into logs and putting our logs through our proprietary three-step aging process. Called wood alchemy, this new science allows us to influence the spalting process and consistently produce commercial grade spalted maple veneer and plywood.