Cork panel dimensions: coincidence or logic?

 

At first glance, it may seem that when it comes to cork boards—just like many other products—larger formats mean better quality: fewer joints, faster installation, and a more impressive look. In reality, however, the size of the board is not about aesthetics or a manufacturer’s arbitrary choice but the result of strict technological and physical limitations arising from the very nature of the material and its processing method.

In this article, we’ll explain where these limitations come from, how cork boards are made, and why certain dimensions have become the industry standard.

 

Table of Contents
1. Introduction
2. Cork boards
3. Expanded natural cork
4. Decorative cork panels
5. Summary
6. FAQ

 

Cork boards

Where natural cork comes from

The primary raw material is the bark of the cork oak tree (Quercus suber), which grows mainly in Portugal, Spain, and southern France. The tree itself is never cut down—only its bark is harvested, making cork production fully renewable and environmentally friendly. After harvesting, the bark is seasoned, dried, and ground into granules of varying sizes.

These granules form the base of what is known as agglomerated natural cork—a material created by binding cork particles through the application of heat, pressure, and—depending on the type—either a natural or synthetic binder. The process for producing expanded natural cork differs slightly, which we’ll discuss later in this article.

Agglomeration and block formation

Cork granules are placed into molds, where they are pressed under high temperature. This is the agglomeration stage, during which production blocks—large solid cork masses with precisely defined dimensions—are formed. In practice, these blocks determine the maximum possible size of the boards that can later be cut from them.

The block size depends on the mold design and the technical capacity of the machines—especially presses, which must ensure even pressure and temperature throughout the entire mass. Oversized molds lead to uneven bonding, resulting in deformations, air pockets, or delamination within the board’s structure.

Production blocks and their impact on board dimensions

A production block can be compared to a “loaf of cork bread”—it has a specific volume defined by the mold’s size and the press’s performance. Each cork board is simply a “slice” cut from this block. This means that the maximum dimensions of a board depend directly on the size of the production mold, which is limited by both the equipment and the physics of the bonding process.

If the mold were larger, its central part wouldn’t heat evenly, and the material wouldn’t achieve the right density—resulting in a soft, porous, or brittle center.

Why standard boards measure 640 × 940 mm

The most common size for agglomerated natural cork boards is 640 × 940 mm, which directly corresponds to the size of the production blocks created in molds with specific depth and width parameters.
This format isn’t random—it represents an optimal balance between production efficiency, dimensional stability, and ease of transport and installation.

Larger formats carry a higher risk of:

• warping during cooling,

• uneven compression,

• cracking during cutting or handling.

That’s why the 640 × 940 mm size became the industry standard—not because anyone decided so arbitrarily, but because technology simply doesn’t allow for larger sizes without compromising quality.

What happens when we try to “go bigger”

Attempts to create larger formats usually end in failure—the material bends, cracks, or loses dimensional stability.
Often, the board looks fine right after being removed from the mold, but within days—once temperature and humidity stabilize—deformations and microcracks begin to appear.

For this reason, manufacturers stick to sizes that guarantee the best quality and consistency. When it comes to cork, “bigger” doesn’t mean “better.”

 

Expanded natural cork

Different technology = different limitations

Expanded natural cork is a completely different material from traditional agglomerated cork. Although both are made from the same raw material—cork granules—their production processes differ fundamentally.
In the case of expanded natural cork, the granules are not bound by any adhesive but fused solely through the action of heat and steam. The high temperature activates the natural resin contained in cork—suberin—which acts as a binder, joining the particles into a solid mass.

This is an ecological, pure process—but one that’s much harder to control. Without external binders, any imbalance in temperature, density, or steam flow can create internal stresses, which in turn limit the maximum size of the blocks and boards.

Differences in density, expansion, and cooling

During the expansion process, cork increases its volume by several dozen percent—a result of the gases trapped within the cork cells expanding. In practice, this means that temperature and pressure inside a large block are distributed unevenly.

The center heats more slowly while the outer layers heat faster, leading to variations in density and hardness. When cooling begins under such conditions, the block starts to “move”:

• the center may remain slightly foamy and soft,

• while the edges harden and shrink more quickly.

As a result, internal stresses appear, causing the board to crack or bulge either right after it’s removed from the mold or later during the drying stage.

This is why the technology behind expanded natural cork does not allow for forming large-area blocks—the bigger the mold, the higher the risk of nonuniformity. Ultimately, this limits the finished board dimensions.

Why large expanded natural cork boards crack or deform

In theory, you could try to make a board larger than 500 × 1000 mm, but in practice it would be technologically impractical and quality-wise too risky.
During cooling, large expanded natural cork boards:

• crack along lines of highest stress,

• warp due to uneven shrinkage,

• lose flatness and become unsuitable for installation over large areas.

That’s why the 500 × 1000 mm format has become the natural maximum—it’s the size at which thermal control can be maintained, density remains uniform, and dimensional stability is preserved.

Thanks to this, expanded natural cork boards retain their best qualities: high thermal and acoustic insulation, natural resilience, and complete resistance to biological degradation—without compromising quality.

 

Decorative natural cork panels

Practical factors: installation, weight, stability

For wall-mounted natural cork, beyond technological aspects, practical factors are crucial. The board size of 300 × 600 mm isn’t accidental—it’s the result of extensive installation tests and real-world use.
This format is lightweight, handy, and easy to apply even for a single person. It can be trimmed and positioned precisely on the wall without risking edge damage.

Larger boards, although they cover more area in theory, are harder to control during gluing: their weight makes it more difficult to keep them perfectly level, and any small error in pressure or adhesive amount can cause unevenness and lifted corners.

Oversized formats = problems during application and bonding

When installing wall natural cork, it’s not just about aesthetics—the key is a stable bond to the substrate. Natural cork is flexible and reacts to temperature and humidity changes, so it requires adhesive forces to be distributed evenly.

With large boards, achieving perfect adhesion across the entire surface is more difficult—even slight differences in adhesive amount can lead to:

• air bubbles,

• lifting corners,

• stresses that eventually cause the board to pull away.

In addition, larger elements are more prone to deformation under their own weight. So while they may look appealing at first glance, their durability and installation stability are significantly worse.

Ergonomics and aesthetics—why smaller boards look better

The 300 × 600 mm format is not only practical but also aesthetically versatile. It allows you to create regular, rhythmic layouts and to match the pattern to a room’s proportions. With smaller formats, the joints are subtle yet visible—highlighting the material’s natural character and texture.

Oversized boards disrupt visual balance: they look bulky on the wall, and their edges draw attention instead of harmonizing with the texture of natural cork. What’s more, any minor wall irregularity becomes more noticeable, because a larger board doesn’t “follow” the substrate as well as a smaller one.

This is precisely why the 300 × 600 mm format is considered an optimal compromise between ease of installation, durability, stability, and the final aesthetic effect.
It’s not a coincidence but the outcome of experience and practice, showing that with natural cork—as with other natural materials—smaller often means better.

 

Summary

At first glance, the size of a natural cork board may seem like a purely practical or aesthetic matter. In reality, every dimension is backed by clear technological logic and manufacturing experience that define what is feasible and durable.

Cork board dimensions aren’t random, nor are they the result of arbitrary manufacturer choices. They stem from:

• the nature of the raw material itself, with a defined cellular structure that reacts to temperature,

• technological limitations, such as mold size, press capacity, and control of the bonding process,

• practical considerations related to installation, weight, stability, and the look of the finished surface.

That’s why larger boards, though tempting at first, tend to cause more issues than benefits in practice.
Natural cork is a “living” material that calls for respect for its limits—and understanding where its dimensions come from is the best proof of technical and quality awareness, both for the manufacturer and the user.

 

FAQ

1. Why can’t I order a natural cork board in any size I want?

Because board size is strictly tied to production technology and the properties of natural cork. The blocks from which boards are cut have fixed dimensions determined by press capacity, mold size, and the bonding process. Scaling up the format would lead to deformation and loss of quality.

2. Where do the standard sizes 640 × 940 mm and 500 × 1000 mm come from?

They’re derived from the size of production blocks. For agglomerated natural cork, 640 × 940 mm is the optimal format obtained from standard molds. For expanded natural cork, the binder-free fusing process enforces different blocks—hence the 500 × 1000 mm limit.

3. Do smaller boards mean more joints on the wall?

Yes, but that’s not necessarily a downside. With natural cork, the joints are a natural part of the composition—subtle and in keeping with the material’s structure.