Rustic flooring has grown in harsh climatic conditions

Color, size, and the number of knots, illustrated by the growth rings – these are the basic variables that determine the classification of wooden floors into categories ranging from cleaner decors to livelier and the most rustic. "Calm" coverings with minimal color variations and almost no knots are obtained from the inner parts of trees that grew in temperate climatic conditions. In contrast, rustic floors with significant color differences, clear knots, and cracks come from trees in harsh northern climates and are made from the outer layers of the trunk.

Of course, each manufacturer has their own labels for their floors, which should hint to the customer whether the covering is more monolithically colored and knot-free, thus clean, or if it is "genuine" wood, i.e., rustic design. For example, the oldest European wooden flooring manufacturer, Swedish Kährs, classifies its three-layered floors into five groups – Calm, Variation, Lively, Dynamic, and Expressive. "Classification is mainly influenced by knots, their size and quantity, color variations between individual boards, and cracks. It is usually just a general description, as most manufacturers keep the exact classification under wraps. How many knots can be on a board, how big they can be, what constitutes a small knot – that's usually not something they will tell you," says Milan Mrkáček, regional sales manager of Kratochvíl parket profi, which celebrates thirty years this year and has been the exclusive importer of Swedish Kährs floors all this time.

The tree for a rustic floor had more branches

What exactly is a knot, such a crucial element for flooring classification? "People sometimes cannot imagine what a knot actually is. Simply put, it's the place where a branch grew," continues Milan Mrkáček from KPP. Therefore, it can simply be said that the more branches a tree had, the rustier the floor made from it can be. "Naturally, if you look at a tree, each one has completely different branches, varying in width and size. Additionally, during wood processing, various shapes of knots can appear – they can be large, small, artificially created using filling where there was some defect. Knots from branches often have a crack, usually in the shape of a cross, which is filled, and this is called a cross knot. In contrast, a healthy knot is just a darker spot from a cut branch.”

Cracks, which appear mainly in livelier and especially in distinctly rustic floors, develop within the grain over the years. "Their origin is dependent on many factors, humidity, temperature... Cracks can form even during processing, as the wood in the given spot may have higher moisture than the rest of the trunk and could crack due to drying... But I have also seen a floor with a crack that resulted from a lightning strike...," adds Milan Mrkáček from KPP.

Animals can also leave their marks in wood, like woodworms. Just for reassurance, such floors should not be feared, because woodworm is a parasite that needs a certain moisture level in the wood to exist, so it is safely eliminated during the manufacturing process (wood drying).

Differences in color are significant, not the color itself

The color of floors is influenced by additional details such as sapwood, dark streaks, heartwood, or the white wood. "No wooden floor has a uniform color, and all the mentioned elements describe the color. For instance, characteristics of oak include the sapwood, which some call eyes or piglets. The sapwood creates irregular elongated streaks that can give the impression that the spot is untreated. Dark streaks are very dark shades in the wood grain. Heartwood is also known as tannin; they are essentially proteins that protect the wood from rot, also creating a certain color hue in the wood,” explains an expert from Kratochvíl parket profi. It is important to note that although it may seem so at first glance, a light shade is not synonymous with a calm classification, nor is a dark one with rustic - the essence of classification is not the color itself but the differences in color.

The cleanliness or liveliness of the decor does not depend on the tree species, but on the part of the trunk from which the floor is made

Wood is a natural material, and every board produced is unique. "There are no two identical boards in the world, truly, each piece is unique,” continues Milan Mrkáček from KPP. Whether the decor is cleaner or more rustic is less about whether the floor is made from oak or cherry, and rather about which part of the trunk it was made from. "If you want a clean floor in a 1-strip decor, you need, to put it simply, the inner part of the trunk. On the other hand, to produce a livelier, rustically styled floor in smaller strip formats, you can utilize a larger part of the trunk from the outer perimeter. This is why, when you look at the price levels of wooden floors, the 1-strip and clean floors are more expensive than rustic 3-strips. Simply, there is more material for smaller livelier formats: You can produce three times as many 3-strips in a livelier design from one trunk than clean 1-strips."

Rougher conditions produce more rustic wood

And another significant fact regarding what kind of floor will be made from a tree is the place where the tree grew. For example, for the liveliest decors, Kährs uses oaks that grow in the harshest climatic conditions, in the coldest temperatures. Conversely, the cleanest oaks come from temperate climates. "Let’s imagine an experiment where we took two oak seedlings, planted one here and took the other to Siberia. If we were to fell both oaks at the same time after fifty years, we would find that the oak that grew in Siberia, and was therefore exposed to much harsher climatic conditions, yielded a significantly rustier floor than the oak that grew here," adds Milan Mrkáček, regional sales manager at Kratochvíl parket profi, explaining why this is the case: "Both the large temperature differences and the extreme cold intensity and duration are decisive factors. Overall, it can be said that frost leads to the drying of the wood, which manifests itself as cracking. Wood exposed to extreme frosts therefore contains a greater number of cracks than wood in moderate conditions. There is a common (false) impression that the air is humid during winter – it is exactly the opposite. Frosty air is very dry."

A guide to the classification of Kährs wooden three-layered floors

CALM floors are made from the cleanest boards. The floor features a calm and uniform appearance, showing only slight differences in grain and color between individual boards. It may contain small knots.

VARIATION floors are those where greater color differences can occur across the surface, characterized by smaller differences in grain and may contain small knots. But it is still a relatively clean classification.

LIVELY floors are more rustic, characterized by wood texture, prominent growth rings, and knots. The floor gives a lively first impression.

DYNAMIC floors are very lively, made from boards with a large number of knots and cracks. The floor naturally takes on a dramatic and rustic appearance, which is also very pleasant and warm. Various color tones occur on the floor.

EXPRESSIVE floors make a strong impression at first sight, representing wood in its most basic and most natural form. The floor is distinctly rustic with noticeable knots and cracks extending several centimeters long on the board. It has striking grain and wood structure and significant color deviations. It was made from the outer perimeter of the tree that grew in harsh northern conditions. For some decors, additional rustic elements are also added by hand, such as so-called pegs, designed to evoke that the floor is truly antique.

The trend is turning towards calmer decors

And what classification is currently the most popular? "In the past, we recorded a gradual transition to the liveliest decors; it wasn't long ago that Expressive floors were the most sought after. That is no longer entirely the case; we have taken a step back. The current trend is turning towards cleaner decors, so today we mostly find ourselves between Lively and Dynamic, and the trend is also slightly heading towards cleaner Variation classification," comments the developments Milan Mrkáček from KPP, and he adds a practical piece of advice: "I wouldn't rely solely on a sample when selecting a floor. Even though a half-meter sample may seem large, I would also request a photo of the decor in a larger area from the supplier. It always depends on which part of the board the sample was produced from. And we have floors that are relatively rustic, but when you take out ten strips from a package, you can find one that is quite clean. And if the sample is made from that part of the floor, the customer can be very surprised that they chose based on a clean sample, but the installed floor is rustic. Therefore, I wouldn't undervalue the selection and aside from the sample, I would recommend looking at the floor in a larger area through a photo."