Cork powder and granules – ecological applications

Cork powder and granules are the main by-products of the cork industry, one of the leading economic activities in Portugal and other Mediterranean countries. Many applications for this product are anticipated, ranging from cork stoppers to agglomerates and briquettes for use as an adsorbent in the treatment of gaseous emissions, water and wastewater.

Cork biomass was used in its original form as a biosorbent for heavy metals and oils, and is also an activated carbon precursor for removing organic pollutants in water and volatile organic compounds in the gas phase.

The use of cork to solve environmental problems, namely oil spills, is the first commercial application of the cork potential of sorbent. The variety of raw materials that can be produced or extracted from cork has attracted the attention of many researchers.

The chemical composition of cork has been studied since the 18th century (Conde et al., 1998), but full knowledge of the chemical properties of cork, and even less of all its potential uses and transformations, is not yet complete.

In addition, since the beginning of the 21st century, the Portuguese cork industry has been investing in research and development: in the period 2000-2002 alone, 35 patents were registered, while in the previous decade only 19 were registered.

According to the Portuguese standards NP-114 and NP-273, cork powder is a material with dimensions smaller than 0.25 mm (Gil, 1997). There are different types of cork powder depending on the origin: grinding, granulating or pre-grinding powder; cleaning powder, no pollution; finishing powder from cutting and grinding operations; finishing powder for agglomerated cork slabs; finishing powder of agglomerated cork and discs; insulating powder for cork slabs (Gil et al., 1986).

A mixture of these powders is considered “flaming powder” as it is used to feed boilers due to its high calorific value (Fernandes et al., 2010; Gil, 1997). Other applications include use as a filler, mixed with adhesives, to improve the quality of corks, production of linoleum, use in agglomerates, briquettes, agricultural substrates, chemical sources (extracts)

Being an environmentally friendly and cheap material, cork powder can also be used to produce activated carbons with high specific surface areas, comparable to commercially available activated carbon, or it can be used directly for the adsorption of pollutants as a biosorbent. It is also used commercially as an absorbent during oil spills

Cork as a core material for multi-layer constructions

Cork is perfect as a component material for various types of laminates and substrates. You can use it as a core in plywood or inside plasterboard. The extensive use of multi-layer panel material has made it the material of choice in several industries and applications such as flat, massive and multi-layer door panels, super insulating window frames, partition panels for office and marine applications.

Agglomerated cork can be considered a suitable material for use as a core layer in sandwich panels: it has high impact resistance, good thermal and acoustic insulation properties and excellent vibration damping properties (Gil 2007; Fortes et al. 2004).

Cork is a natural material with a cellular structure with an interesting set of properties for sandwich structures, i.e. low density, very low liquid and gas permeability, high compressibility and dimensional recovery, low conductivity, chemical stability and durability (Pereira 2007).

Several studies have already considered the use of expanded cork as a core material, incl. carbon-epoxy sandwich panels (Reis and Silva 2009; Castro et al. 2010). Expanded cork agglomerate is a 100% natural cork product, made from waste and cork residues, or from industrial cork waste unsuitable for other uses (Diaz et al. 2003; Ferreira and Pereira 1986; Pereira and Ferreira 1989).

Expanded cork agglomerates are produced using cork granules in a closed autoclave at high temperature (about 300 C) and pressure (about 40 kPa) without the use of glue (Pereira and Ferreira 1989; Baptista and Vaz 1993).

These process conditions lead to: expansion of the plug cells and thermochemical degradation of the cell wall (Pereira 1992), along with the release of by-products that act as natural glues between the agglomerate granules (Pereira 1992; Amen-Chen et al. 2001; Rosa and Fortes 1988a) ).

Such ecological, light and cheap sandwich panels can be used as elements of non-structural structures such as partition walls. The use of sandwich structures has been steadily increasing over the past half-century.

A cork in the attic – a functional solution

Cork on attic is a proven insulation made of breathable and diffusion-resistant materials. Such a floor does not age, has above-average soundproofing properties and is highly resilient. Due to the natural bubbles formed in the process of natural expansion of the cork material during thermal treatment, it has a very good heat storage capacity.

The choice of a cork also significantly affects safety in the event of a fire. Cork does not catch fire quickly, it only smolders and is a product of the so-called self-extinguishing. The numerous advantages include resistance to rot, fungus and mildew, and after a short airing it is practically odorless. Most often, such a cork is placed on the OSB boards or directly on the log supports.

The cork is also suitable for roof insulation. Expanded cork, for example, is glued or nailed to the inside of the roof, which is not a difficult task in the case of a construction lath. These panels are lightweight and easy to cut. For this reason, they are perfect for warming and soundproofing. Cork insulation boards are available in various thicknesses. The thicker the sheet, the better it insulates. It is recommended to use boards about 6 inches thick to insulate the roof with cork. In order to avoid heat loss due to thermal bridges, the boards can be laid diagonally with respect to each other. In this way, the insulation will be more efficient in these difficult zones.

Natural cork in fishing

Fishing with a floating cork is essential for coastal fishing. Floats made of natural cork, formerly mainly made of wine corks, were and are often used in fishing and fishing. While anglers use it like floats of other materials, fishermen use the cork to mark the hook’s location by dragging it around the lines surrounding the fishing nets.

Cork is mainly used here because of its buoyancy and its ability to float. Such floats, unlike the factory foam and plastic ones, are delivered with a heavy weight, so that the set with them flies to the desired point without deflecting in the wind.

The unique structure of cork cells, which are filled with air, makes natural cork lighter than water. On the Internet you can find many fishing shops offering cork floats or fishing rods with handles made of natural cork, because it is not as slippery as synthetic handles.

In many places, mainly in the Mediterranean, it is used more often than other materials due to its availability. You can also make a cork float yourself with a little time and willingness.

The DIY tutorials suggest that you drill a 3mm hole in the center of the wine cork and stuff it with a bamboo stick. Using an authorized drill and sandpaper, give the cork plug a characteristic teardrop shape, trim the stick and on the other side finish the float trimmed with a safety pin. Then wrap the tip with thread and, if necessary, paint it so that it is visible on the water. Below you can see an example video tutorial on how to do it yourself at home.

Cork granules, on the other hand, are sometimes used as a bait additive. This is the case, for example, in the case of carp baits. Thanks to this addition, cork balls used in fishing can pick up a typical protein ball of similar size. Since cork is a natural product and it floats very well, cork pellets are added to the groundbait mixes to produce pop-up balls or hookbaits with reduced density.

Printing on natural cork – is that possible?

As befits a versatile material, cork is also subject to various printing techniques. It’s not just about technical cork, but also about cork fabric or wine corks, for example. The technology makes it possible to preserve the natural properties of cork while giving it a unique look through various printing technologies

Cork materials differ particularly in terms of flexibility and strength, making them suitable for industries as diverse as construction, transportation and footwear. Corks are no longer just corks, you can do absolutely anything today with its.

A very popular method of printing is screen printing, e.g. on cork pads, cork balls. Our offer includes this type of prints.

In this way, you can achieve amazing results and, with a little inspiration, create a unique placemat at home, a pattern on a cork board on the wall or on a cork yoga mat.

The cork also uses digital prints, e.g. with advertising pads. Such marketing procedures can be seen especially in pubs where you can often find cork coasters for beer and drinks printed with screen printing or digital printing. Such washers are also used by various types of companies to increase brand awareness among their customers.

Recently, however, the quite fresh trend of images on traffic jams has made a sensation. They are made on cork plates. Some companies, especially in Western Europe, have the option of ordering personalized photos by printing, which look very attractive and can be a truly unique gift for a loved one.

Of course, these are not the only printing methods used. The photos can be put on a pad or a cork plate using the dye-sublimation printing method. Then these photos do not differ from their counterparts on photographic paper. The only difference is the unusual cork carrier. In the video below you can see how this technique works in practice:

Another type of cork, if not the most popular, on which the print is used is the cork fabric and the most commonly associated cork product, i.e. cork wine stoppers. In the case of the former, printing on cork bags and generally understood cork accessories is the most common. This industry is especially popular in Portugal and the multitude of handbag designs and shapes is stunning there.

However, the first print that appeared in the 18th century was that on wine corks. Wine producers and winery owners have labeled their products with this imprint for over 200 years. Each natural cork stopper shows the logo of the alcohol manufacturer when opened.

The first Google brick-and-mortar store decorated with natural cork

A month ago in New York, Google opened its first brick-and-mortar store. From our point of view, the information would have gone unnoticed were it not for the fact that this most profitable company in the world decided to decorate the premises with cork and cork furniture.

When designing the interior, the discoveries of a relatively new field of science, i.e. neuroaesthetics, were used. This field studies how visual aesthetics affects our body and mind. At the company’s point in the Chelsea district of New York, furniture designed by Polish designer Daniel Michalik was used. Furniture, including oval-shaped sofas and tables, is made of light wood and cork in neutral colors, thanks to which the products will stand out.

The cork was used, among others to obtain LEED Platinum certification – on the higher possible certification as part of the evaluation of green buildings. The interior is designed in such a way that the final recipient will feel as comfortable as at home.

Near the main entrance is a 17-foot-tall circular glass structure (designed and manufactured with local New York partners), dubbed the Google Imagination Space. With custom interactive screens with rotating exhibits, visitors can enjoy the best products and technologies, starting with a Google Translate experience and our machine learning capabilities.

A thin black metal line extends across the store, delineating a seamless path and eye-catching between the various displays. The central circular counter that functions as a support desk has a neon halo that says “Here to help” many times in the ring.

Seats in the form of benches, pouffes and stools can be used by buyers and those seeking advice or assistance with the product. The windows feature illuminated “reveal boxes” that showcase Google products and allow passers-by to interact with them using augmented reality technology.

3D printing from natural cork

Natural cork has also found its place in the industry of 3D printing which has been developing for several years. They are filaments, i.e. materials used in the process of 3D printing by the method of depositing the melted material. In 2015, the European 3D printer filament manufacturer ColorFabb developed an innovative filament called corkFill and, as the name suggests, it should offer cork-like properties as it is a mixture of cork and ColorFabb PLA / PHA filament.

The photos available on the company’s website show a high level of detail and very good-looking color results of prints made with the new cork filament. As it is based on PLA / PHA filament, printing is easier and does not require the presence of a heated build platform (HBP) on the 3D printer.

PLA is one of the most popular filaments used in 3D printers. The abbreviation PLA refers to polylactide or lactic acid. Interestingly, cornmeal or sugar cane are used for the production of this material. PLA is considered a biodegradable and biocompatible material – it is used in implants or stents and in many other products that we use every day.

In 2019, as reported by the portal, the Portuguese student Tatiana Antunes managed to create a 100% biodegradable cork filament for 3D printing. She developed this method at the University of Aveiro (UA) as part of her master’s thesis in materials science. The topic of her work was the problem of the formation of cork waste in the production of natural cork stoppers.

All you ever wanted to know about cork

And no, by “cork” I do not mean the Irish city of Cork (although it’s probably a very nice town). Cork is an unique material that is obtained from the bark of cork oak tree and has numerous uses. The one that comes first to the mind is, obviously, wine bottling. It’s hard to imagine a wine without a cork stopper. However, it is not the only use of the cork. Ever heard about cork roll or cork flooring? Yes, it is truly a remarkable material.

Where it all begins

The story of cork begins with the bark of cork oak tree. It’s not that easy to obtain the bark itself because the whole process is strictly regulated by law. Obviously, everyone would like to have a cork board or even a cork wall. But it is not that simple. The cork oak is an eternally green tree which lives for around 150 to 200 years. It grows best on the terrain of Mediterranean Sea and that is why it’s easy to meet a cork oak tree there — most commonly it is found in Portugal, where it takes up to 22% of the area of the whole country. It’s impressive, isn’t it?

The process of obtaining the cork

So, if you happen to stumble upon a cork oak, you cannot really just cut down the tree and strip the bark off it. Basically, only qualified and trained people can do so and they are allowed to peel it off the tree once in nine years, mostly during the vegetation period, when the cork oak may grow a new bark really quickly. During the procedure the tree cannot be cut down and it cannot be damaged in any other way. You do not want to destroy the delicate ecosystem just to have a great cork board.

Debarking the tree

You may ask, how it’s possible that you can obtain the bark without cutting down the tree. Well, it is actually the only tree a human has met, that does not need to be cut down for its bark, since it grows in two layers. The internal one is alive and is a foundation for the new, external layer of the bark, which protects the tree from the temperature change. When the external layer dies, it can be peeled off with a special axe, causing no damage to the tree itself.

The harvested cork

The cork after being peeled off, is placed somewhere under the influence of the air, so it can improve its quality and be even better. This procedure lasts a few weeks, after which the bark patches are cooked with steam so all undesirable juices, insects and others disappear, leaving the bark clean and ready for further treatment, where a new cork wall, cork board or cork roll will be made for you.

Want to have an eco-wall? Try out the cork one!

It’s pretty trendy to be an eco-person nowadays. Just show that you care about the environment which is surrounding us and you are going to have a good reputation among the people. Now, many humans wonder whether it’s really possible to be pro-eco all the time. Ecological products are usually acquainted with either low quality or high price. Some also wonder if it’s really possible to be pro-eco when building a house. Of course, just try some cork walls!

Where’s the trick?

Cork? – you will ask. – But it’s used only for wine stoppers! Well, not exactly. Cork flooring, cork walls… Yes, you can make everything from cork, which is also the most ecological material ever, because it’s made from the bark of cork oak tree and it does not hurt the tree at all. It’s hard to imagine a better quality material that would not hurt the delicate environment of Earth. It’s simply natural and really easy to recycle, while very unique (since it’s a natural material, each piece of the cork will be just different!) and also having some interesting properties: insulating, thermal, acoustic among them. It all makes the cork just the great material for the walls or flooring in your new house. Place the cork wall in the children’s room and it will be just quieter in all of the house.

Why cork flooring?

So who exactly would be interested in having a cork flooring? Obviously, mostly people who are pro-eco and want to make conscious decions about their lifestyle. But not only them. Allergic people may be intrested in cork flooring’s surface resistance to dust and toxins – it doesn’t absorb them, meaning it makes life a bit easier for those who suffer from dust allergy. There’s also a great pro of cork flooring being soft and cushioned – it just makes some things easier and will probably prevent your children from being in pain after a random fall on the floor.

Durable and stable cork flooring

Have you ever considered cork flooring as a suitable choice for your very own floor? In this case you may wonder, whether it’s worth the effort. Yes, the cork flooring or a cork underlay look really good in your flat, but if you have ever seen the wine stopper, you may wonder whether it will last for a long time. Well, it will. We are about to prove to you that your very own cork flooring or cork board may last for a really long time, if you take a good care of it and promise not to treat it too bad. It will be not only grateful, but it is also going to have a graceful look!

The fact is that a cork flooring that is properly cared for may last even forty years, if not more. The cork will resist all cracks, gases, liquids and more. Actually, a lot of people think that cork may burn easily and would prefer not to use it in the room with any chimney. But it’s not true – cork roll is resistant to fire! It will never melt or ignite, unless there’s a really high temperature inside. Some people are worried that heavy furniture may indent cork and therefore damage it quite badly. However, the cork actually bounces back, so the indentations caused by an exceptionally heavy cupboard or sofa will not be permanent and there will be no signs of it left. Your cork roll on the floor will still look quite lovely

Now, the cork due to its resistance to almost everything you can think of is not only stable, but really healthy. It’s recommended especially to allergic people, who have to be careful with the potential allergens in the house – cork helps in keeping them out.Generally speaking, cork underlay or cork wall are more stable than a wooden floor or wall. Most people never complain of it shrinking or otherwise degrading. It is literally indestructible.

You still cannot believe that a cork oak tree can give something that is a good material for the floor? Look at the Library of Congress (Washington DC) then. It was founded in 1800 and its cork flooring is still on the roll. Nobody ever complains about it falling out or being unstable. There are also many other numerous examples of an adhesive cork or cork board being used in buildings for ages and they all are still as good as on the first day! Yes, it is unbelievable, but it also means that we’re really lucky ones to have such a good tree as cork oak which will give us so much good isolation cork and other things that we can enjoy.

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