Canadian Woodworking
Bog oak

Bog oak

Quercus sp.

Author: Peter Mac Sween

Bog Oak is one of the rarest woods in the world.  Each piece of Bog Oak has a singular life history, driven by a process of fossilization, interrupted by an act of discovery.  Bog Oak has a history that unwinds over thousands of years, resulting in a unique piece of wood.

Picture a forest growing near a vast river system.  Over time, this forest matures with the oaks being the dominant species.  The river eventually slows, and the trees are now surrounded by swamps and bogs.  Trees begin to fall due to storms and other natural processes and quickly sink and are swallowed up by the bogs.

The water in the bogs is acidic and rich in tannins, which are a natural preservative.  Trees will not decay in this preservative rich liquid.  As time passes, the bogs begin to be filled in with organic material.  This prevents oxygen from reaching the fallen trees and stops any decay typically caused by bacteria.

While other species can be found in the bogs and wetlands, the oaks have a particular advantage.  Oaks are a hard durable species and have a high tannin content to begin with.  Consequently, well-preserved oaks are frequently found in bogs.  Specimens up to 8,000 years old have been found entombed within these peat bogs.

Bog Oaks also undergo a chemical reaction while submerged in the bog.  Tannins when exposed to the iron rich water of the bog colour the wood black.  This process takes time and results in wood that has changed from the original tan brown colour of oak to a deep dark brown and finally a jet black.  Mineralisation also occurs.  This is a process where minerals displace organic material in the wood.  As a result of this mineralisation, Bog Oak is an incredibly dense wood.


Bog oak

Bog oak

Bog oak

Bog oak end-grain

Bog Oak are not harvested like regular oaks.  They are typically discovered when land is cultivated or excavated for development.  Working with Bog Oak is a difficult process.  The logs, once exposed to fresh air, quickly begin to decay.  Time is of the essence.  Once any decayed material is removed, the log is usually sawn into quartered lumber.  Drying is difficult and unpredictable.  Kiln drying seems to be the preferred method as it offers the most control.  Waste is always high when drying this lumber.

The process or maturation of the Bog Oak is dependent upon the characteristics of the bog where it came from.  Since no two bogs are similar, every piece of Bog Oak is unique in appearance and workability.  The wood is often two toned, with wood from the outer growth rings a rich black, and then fading to a dark brown as you approach the center of the tree.

Bog Oak can also be sliced into veneers, where it can become panelling, furniture and parquet flooring.  Solid Bog Oak is occasionally used for furniture if larger pieces of lumber are available.  Smaller pieces of Bog Oak are used in turnery, chessmen, knife handles, inkwells and all sorts of decorative objects.

Bog Oak is so rare that there is no information available on workability and other common characteristics such as density, shrinkage rates, hardness, etc.  This is no doubt due to the uniqueness of each piece of lumber.

Time spent in the bog will have a profound effect on the end-product.  Older pieces will not only be darker in colour, but also denser due to more mineralisation.  Bog Oak will dull tools and so carbide tooling is best.  If you work by hand expect lots of trips to your sharpening station.  I would experiment on scraps to determine the best finish.  Oils would be my preference, since they would accentuate the dark colours.

The most famous sources for Bog Oak were the bogs of England and Ireland.  Today, Bog Oak is sourced from Poland, Russia, Ukraine and the Rhine River Valley.  Expect to pay high prices on par with other rare exotics like Ebony and Pink Ivory.

Any large project with Bog Oak will require deep pockets.  However, I can envision buying a smaller affordable piece to make a tool handle or perhaps an interesting door pull.  What is appealing about the use of Bog Oak, is its life story and also the chance to own something that is thousands of years old.

More about Bog oak

The Wood Database specifications: Bog oak
Last modified: July 11, 2022

Peter Mac Sween - [email protected]

Peter's woodworking journey began with a career in carpentry followed by a decade buying and selling veneer. His spare time is spent abusing his guitars and exploring the great outdoors.

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