All About OAK

March 12, 2018

All About OAK

EUROPEAN OAK VS. WHITE OAK

The majority of Monarch Plank’s products (and 100% of our Oak products) are made with European Oak. Some people refer to European Oak as ‘White Oak,’ but the truth is that European Oak is quite different from the wood that we call ‘White Oak’ here in North America. Botanically, European Oak and White Oak both belong to the genus Quercus, which contains over 300 species, but they are composed of completely different groupings of species within that genus. There is no overlap among the White Oak and European Oak groups.

Differences between European Oak and White Oak include: 

  • European Oak is more uniform gray in color, whereas White Oak tends to have more yellow and pink undertones
  • European Oak tends to have tighter grain than White Oak
  • European Oak tends to be more knotty than White Oak
  • European Oak has higher tannin content than White Oak, making it more rot-resistant and more suitable for reactive staining, fuming/smoking and other natural color processes

Both European Oak and White Oak feature significant variations in color and grain caused by a variety of factors. These include: differences within a tree, age of the tree, rate of growth, soil and climate of the region, and most importantly, the genetic differences between the various species within each group.

 EUROPEAN OAK

The predominant species of European Oak are Q. robur and Q. sessilis. Other European Oak species of lesser significance include: Q. afares, Q. macranthera, Q. longipes, Q. imeretina, Q. iberica, Q. pedunculiflora, Q. lamugnosa, Q. farnetto, and Q. mirbeckii. In many areas these species grow side-by-side and easily hybridize.

In Q. robur, the branching of the trunk occurs at a lower level, making the wood more knotty. Q. sessilis is tall and slender, with fewer low branches and consequently fewer knots. The wood in Q. robur is generally more dense than in Q. sessilis, and usually produces a wider-grained wood with higher tannin content. The fact that Q. robur is wider-grained but also more dense seems to be a contradiction - see below under ‘TIGHTNESS OF GRAIN & DENSITY’ for an explanation of why this is the case. In general, Q. robur occurs more frequently in the forests of Western Europe, particularly in France. As you move East into Germany and eventually Eastern Europe,  Q. robur becomes less common. That’s one of the reasons French Oak is considered special and is so prized by wine, furniture and flooring manufacturers.

Some of the Oak that is sold as 'European Oak' is actually from the Russian Far East and consists mainly of Q. mongolica, a species that doesn't grow in Europe at all and has very different characteristics from true European Oak. Due to its proximity to China, a major wood flooring manufacturing center, this Q. mongolica is actually what's being used in many of the products now being sold mistakenly as 'European Oak.' Also, Q. mongolica has been overharvested, often through illegal logging, and is now a protected tree species under the Convention on the International Trade in Endangered Species (CITES). {see below: EUROPEAN OAK vs. RUSSIAN OAK ] Illegal harvesting of Q. mongolica in protected areas of the Russian Far East has also been one of the major drivers of habitat loss affecting the endangered Siberian Tiger.

WHITE OAK

The main species of White Oak in North America is Q. alba, which constitutes about 45% of the standing White Oak timber. Other species that may be sold as ‘White Oak’ include Q. prinus, Q. bicolor, Q. mueh. lenbergi, Q. stellata, Q. macrocarpa, Q. Iyrata, and Q. durandii. Most White Oak lumber sold in North America contains some percentage of Q. alba, and that percentage can be close to 100% in some forests in the Great Lakes region, resulting in greater color & grain uniformity. In Northern Appalachia and the forests of Missouri and Kentucky, White Oak tends to contain a higher percentage of Q. bicolor and Q. macrocarpa. Wood from Arkansas and the South is likely to contain a higher percentage of Q. prinus and Q. Iyrata.

TIGHTNESS OF GRAIN & DENSITY

Across all species, the tightness of the grain is determined by the growing conditions of the tree. A slower growth rate will result in tighter grain.

People generally assume that tighter grained wood is more dense. In most species groups, that is true, but not in Oaks. In Oaks, the spring growth consists of large open vessels, whereas in summer growth, the pores are relatively small. A slower rate of growth (tighter grain) is characterized by a greater proportion of spring wood and a smaller proportion of summer wood. So, in a slow growing Oak tree, due to the higher proportion of large, open, hollow vessels, the wood is less dense. Wood from a fast-growing Oak tree (wider grain) will be more dense. Some companies market their Russian Oak as being more dense than Western European Oak because the cold Northern climate makes for slow growth and tighter grain, but in fact it’s the reverse – the Russian Oak is less dense.

EUROPEAN OAK vs. RUSSIAN OAK

 In addition to the fact that true European Oak (from Western Europe) is more dense than Russian Oak, we also find that it has a more beautiful grain structure. Oak from Russia, especially the Far East, usually features black veining running parallel to the grain, a characteristic of American White Oak whose absence in true European Oak is one of the things that makes it so attractive. But those aren’t the only reasons we avoid Russian Oak.

 Monarch Plank takes great care to source its wood with the utmost environmental responsibly. All of our European Oak comes from selectively harvested forestry operations in countries where forestry laws are strict AND are strictly enforced.

 Unfortunately, illegal and otherwise irresponsible harvesting is currently commonplace in Russia. Illegal logging is a problem throughout Russia, but particularly in the Russian Far East, where harvesting of Oak and other species on a massive scale is reducing the last remaining habitat of the endangered Siberian Tiger. Due to the slow growth rates in these cold northern forests, it will take a long time for the ecosystem to recover. Most of the Oak being harvested in the Russian Far East is processed in factories in China and sold in the United States, where it is usually labeled as ‘European Oak.’ 

TANNIN CONTENT/VARIATION

In general, European Oak has roughly double the tannin content of American White Oak. The higher tannin content makes European Oak more durable (rot-resistant), which is why it was the preferred wood for ship-building throughout European history.  That higher tannin content also allows us to create unique and natural-looking colors via chemical processes that react with the tannins. [See the ‘CREATING COLOR FROM WITHIN – NATURAL REACTIVE COLOR PROCESSES’  blog post for further details about these coloring techniques.]

Within a particular species, localized soil quality and the individual tree’s access to water and sunlight impact the tree’s growth rate, which plays a role in determining tannin content. The large open pores of the spring growth contain more tannin than the smaller pores of summer growth. So, wood from a slow-growing tree with tighter grain (a larger proportion of spring growth) will contain more tannin than a fast-growing tree with wider grain (a larger proportion of summer growth). All other things being equal, trees that grow farther north and therefore more slowly will have higher tannin content than comparable wood from further south.

That being said, in European Oak, genetic differences among species play a much larger role in determining tannin content than does the latitude of the forest or the growth rate of the trees. A different mix of species means that Oak from Western Europe tends to have higher tannin content than Oak from Eastern Europe and the Russian Far East, despite the colder climate. Even within Western Europe, tannin variation in the Oak caused by different species mixtures can be extremely localized. Oak from the Limousin region of France tends to have much higher tannin content than Oak from the nearby Departments of Nievre and Allier, despite the similar climate. This is because the Limousin Oak is mostly composed of Q. robur, whereas the Nievre/Allier Oak is mostly composed of Q. sessilis. In North America, genetics play less of a role in tannin content, as the tannin content among the various species of the White Oak group is similarly low.

Within a particular species, localized soil quality and the individual tree’s access to water and sunlight impact the tree’s growth rate, which plays a role in determining tannin content. The large open pores of the spring growth contain more tannin than the smaller pores of summer growth. So, wood from a slow-growing tree with tighter grain (a larger proportion of spring growth) will contain more tannin than a fast-growing tree with wider grain (a larger proportion of summer growth). All other things being equal, trees that grow farther north and therefore more slowly will have higher tannin content than comparable wood from further south.

That being said, in European Oak, genetic differences among species play a much larger role in determining tannin content than does the latitude of the forest or the growth rate of the trees. A different mix of species means that Oak from Western Europe tends to have higher tannin content than Oak from Eastern Europe and the Russian Far East, despite the colder climate. Even within Western Europe, tannin variation in the Oak caused by different species mixtures can be extremely localized. Oak from the Limousin region of France tends to have much higher tannin content than Oak from the nearby Departments of Nievre and Allier, despite the similar climate. This is because the Limousin Oak is mostly composed of Q. robur, whereas the Nievre/Allier Oak is mostly composed of Q. sessilis. In North America, genetics play less of a role in tannin content, as the tannin content among the various species of the White Oak group is similarly low.





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