Cork Rolls

Popular as an insulating and decorative material, cork rolls have their own specific properties that can affect their resistance to moisture and fire. Here are the key facts:

Moisture resistance

Cork is a natural material that has some water-repellent properties due to its cell structure filled with suberin.

Partial moisture resistance: Cork does not absorb moisture to the same extent as other materials, such as wood, but it is not fully waterproof.

Risk of mould: When exposed to high humidity for long periods of time, especially in poorly ventilated spaces, cork can be susceptible to mould growth.

Use of special impregnation: Moisture resistance can be improved by using protective coatings such as varnishes or waxes.

Resistance to fire

Cork has a natural fire resistance due to suberin, but:

Self-extinguishing: Some cork rolls are self-extinguishing, which means that once the source of the fire is removed, the material stops burning. Fire classification: It is worth checking whether the product has an appropriate fire resistance class (e.g. according to EN 13501-1)

Fire-retardant impregnations: Cork rolls with additional flame retardants are available.

Summary

Moisture: Cork is moderately resistant to moisture, but requires additional protection in humid environments.

Fire: Natural fire resistance is good, but in the case of a high risk of fire, it is better to choose products with appropriate impregnation or certificates.

The production of cork rolls in Portuguese factories is a fascinating process that begins with the harvesting of the bark of the cork oak (Quercus suber) and ends with the precise manufacture of finished products. Portugal, a leader in global cork production, places great importance on sustainability and quality. Here is a detailed description of the process:

1. Harvesting the cork oak bark

Harvest time: The bark is harvested every 9 to 12 years, when it has reached the appropriate thickness (minimum 25 mm). The first harvest, called "virgin cork", takes place when the tree is about 25 years old. Subsequent harvests produce increasingly higher quality cork.

Harvest method: The bark is gently removed using special axes so as not to damage the tree. This process is manual and requires great precision.

Tree protection: The trees are not cut down, which allows the bark to regenerate. Thanks to this, the cork oak can be used for 150 to 200 years.

2. Bark Seasoning

Natural drying: The bark is stored in the open air for 6-12 months. This process allows it to stabilize and get rid of excess moisture.

Quality control: Before further processing, the bark is assessed for structure, thickness and the presence of defects.

3. Pretreatment

Cooking: The bark is boiled in high-temperature water for 1-2 hours to remove impurities, increase elasticity and improve cellular structure.

Cutting and sorting: After cooking, the bark is cut into smaller pieces and sorted according to quality.

4. Grinding and forming granules

Shredding: Lower-quality bark that is not suitable for making wine corks is ground into granules.

Bonding: The cork granules are mixed with a binder (usually an eco-friendly polyurethane glue) and formed into sheets or blocks.

5. Production of cork rolls

Block forming: The cork blocks are compressed and dried.

Cutting: Large cork blocks are cut into rolls of different thicknesses and widths, depending on the intended use of the product (insulation, underlays, decorations).

Wrapping onto rolls: The cork material is wound into rolls, ready for transport and sale.

6. Finishing and packaging

Surface: The rolls can be sanded and impregnated to increase their durability or to give them specific properties (e.g. resistance to moisture or fire).

Packaging: The finished products are packaged and prepared for export. Portugal exports cork rolls all over the world, supplying them to various industrial sectors.

Ecological significance

Sustainability: The production of cork does not harm the trees and is completely renewable.

CO₂: Cork oaks absorb large amounts of carbon dioxide, which helps to protect the environment.

Recycling: Cork is 100% biodegradable and can be recycled.

Portuguese cork factories are a symbol of harmony between tradition, innovation and sustainability, and their products are appreciated for their high quality all over the world

The differences in the insulating capacity of cork rolls and cork sheets are mainly due to their structure, thickness and application. Although both products are made of cork, a natural material with excellent insulating properties, they have different characteristics that affect their effectiveness as an insulating material.

1. Material structure and density

Cork rolls:

Cork rolls tend to have a more open cell structure and are more flexible, making them ideal for applications that require easy adjustment to uneven surfaces. Since cork rolls are often in thin layers, their density can be lower than that of sheets, resulting in slightly lower insulating capacity.

Cork sheets:

Cork sheets, especially thicker ones, have a more compact structure. They are usually made of denser cork, which allows for better acoustic and thermal insulation. A thicker layer of cork provides better protection against heat loss and noise. Cork sheets can also be impregnated or reinforced more easily, which improves their insulating properties.

2. Thickness and insulation efficiency

Cork rolls:

Cork rolls are usually thinner (although they can come in a variety of thicknesses). Due to their thin layer, the rolls are more suitable for applications where high insulation is not required, such as insulating underlays, decorative underlays, and simple acoustic insulation projects. The thin layer also means that the rolls may not provide as much protection against moisture and temperature compared to sheets.

Cork sheets:

Cork sheets, due to their greater thickness, offer better acoustic and thermal insulation, and can also be used in areas where more advanced protection against noise, cold, and even moisture is required. Due to their structure, cork sheets are a better choice for applications that require higher insulation parameters, such as in construction.

3. Application in acoustic and thermal insulation

Cork rolls:

Due to their flexibility and shape, cork rolls are mainly used for acoustic insulation on smaller surfaces, such as floors, walls or ceilings in places where there are no great requirements for the thickness of the insulation layer. They are also used for thermal insulation in more local applications. Rolls can be easier to install in irregular spaces.

Cork sheets:

Cork sheets offer better insulation, both acoustic and thermal, in more demanding applications. Due to their greater thickness and density, they are an excellent material for insulating floors, walls, ceilings and in underfloor heating systems. They are also used for sound insulation in rooms where greater efficiency in noise reduction is required, such as recording studios or offices.

4. Mechanical properties and durability

Cork rolls:

Although cork rolls are very flexible, their durability may be slightly shorter compared to sheets, especially in places with high traffic. They are more susceptible to mechanical damage (e.g. scratches), which can affect their insulation properties over a long period of use.

Cork sheets:

Cork sheets are more durable and more resistant to mechanical damage. Due to their compact structure, they are less susceptible to deformation, which makes their durability in applications requiring long-term performance (e.g. building insulation) higher.

5. Cost and ease of installation

Cork rolls:

Due to easier installation (flexibility and ease of cutting), cork rolls can be cheaper and easier to process in less demanding applications.

Cork sheets:

Cork sheets are more expensive, but offer greater insulation efficiency. The installation of the sheets may require greater precision and tools, especially in the case of applications in construction.

Summary

Cork rolls are more flexible, easy to install and suitable for less demanding applications where high insulation is not necessary. They are mainly used in acoustic and thermal insulation in small rooms or simple applications.

Cork sheets offer improved thermal and acoustic insulation, especially in thicker versions. With their higher density and thickness, cork sheets are ideal for applications requiring more advanced protection against noise and temperature.

The choice between rolls and cork sheets depends mainly on the specific design needs and insulation requirements.