Little wood science
There are types of wood (at HolzTraum acacia, rosewood, laburnum, mirabelle plum and oak) that inherently have a darker core of wood surrounded by a layer of younger, lighter sapwood. The term sapwood is used to describe the not yet fully mature wood in which the nutrients are transported.
Personally, I like the play of the two colors of these trunks. But it means that I usually have to cut these veneers myself, because in the veneer industry the sapwood is considered an undesirable waste.
From the middle of the trunk, extremely hard fibers radiate outwards through the annual rings like a sun. These rays are made of very hard fibers, much harder than the wood that surrounds them. For the tree, this has the advantage that a high level of stability is possible with a lower weight of the branches. In the veneer, the wood rays look like either dots or streaks that shimmer in the light, depending on the angle at which the veneer was cut. The wooden steel highlights in my collection include elm, mirabelle plum, common heather, laburnum and oak.
If a tree trunk falls into a moor and, as luck would have it, it matures there for several hundred years in the absence of oxygen, then the wood turns greyish-black and, to my delight, becomes more flexible, which means it is easier to process.
Such trunks are rare, which is why bog wood is an expensive rarity.
I process bog elm and bog oak.
Wood containing tannic acid in particular (oak and chestnut in my case) discolours dark brown to black when it comes into contact with ammonia vapours. Oak furniture in horse stables led to this discovery.
Today, whole trunks are industrially treated with ammonia in huge smokehouses. The result is evenly dark wood. The process has absolutely nothing to do with smoke.
When metal ions penetrate wood, it turns dark. A tin can carelessly left in a puddle will create an unsightly black ring on the wood surface. Sometimes you can undo the misfortune with citric acid.
A Swiss veneer factory has developed an oxidation process so that they can produce evenly gray veneer. I call it holm oak because it is the color of stone.
Unfortunately softwood is not well suited for wooden rings. It’s just too soft. I tried it with the hardest possible softwood, a juniper trunk. The aroma when slicing was delicious, but you could score a notch in the finished ring with your fingernail.