Cork! How to recognize durable and high quality cork fabric

Over the years, so many many questions have we been asked about cork. Is it durable? Is it brittle? Is it waterproof? With this article we hope to answer these questions.

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“How can your cork products be so expensive when I got this in Portugal for half the price?” The answer is in the details.

 

Different works, different corks

The versatility of cork as a material means there’s a plethora of uses of this material, from flooring to insulation, to accessories made of cork fabric. However different types of cork processing are indicated for specific uses. Therefore the kind of process one does to cork bark for a floor tile is normally not indicated for example for a cork wallet or umbrella. But what are these different processes? Let me explain.

Cork Agglomerate

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Cork Agglomerate is perhaps the cheapest kind of cork processing and there’s a reason for it. Essentially it’s any kind of cork grounded to whatever grain density is needed. This is the utmost re-usability of cork as it’s often made of used cork products such as wine stoppers or anything made of cork. Once the cork is grounded. The cork is then poured into a vat where it’s boiled. The boiling process makes the cork release a natural resin that binds the different granules together. With this process one can turn the normal sized cork bark into blocks of whatever use you need it for.

Pros: Ideal for large scale works that will use cork. Normally used in industrial settings or construction. Though it’s the most common use of cork due to how cheap and reusable it is. It can be died in different colors and has a high tolerance to synthetic dyes.

Cons: The cork granules will eventually flake away little by little. In a plank or cube form is ideal though it is brittle and not flexible. If cut into a sheet it will simply break apart.

Main uses: Insulation, wine stoppers or any kind of industrial sized where cork is needed. Lisbon harbor has famously incorporated cork granules with concrete into it’s foundations creating pillars of concrete with less weight in a very swampy part of the Tagus river.

Not Recommended For: Cork fabric! It’s low degree of flexibility means it will brittle away and soon enough your cork purse will decay into tiny cork pieces.

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Different grounds of cork granules drying in the sun Photo circa 1940s by Artur Pastor

Cork Stripes

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Cork Stripes is at least 40 years old was for a long time the most common use of cork besides agglomerated cork

Cork Stripes is composed of homogeneous sliced planks of cork bark bound together into a block and then cut into slices to whichever degree is needed. The planks are conjoined vertically and normally have only a couple of centimeters in thickness. As the planks are placed vertically a number of horizontal darker brown lines are visible. These lines, or pores, are naturally dug on the cork bark when it’s still in the tree. Insects and fungus create them to reach the livable cork bark on the cork oak. As the cork bark grows they slowly dig deeper and deeper. The planks are also of a lower degree of cork bark representing more pores and more inconsistencies in the final product making it a relatively cheap cork bark to obtain but with a lesser lifespan.

Pros: Cork stripes is the next step from agglomerates as it shows the typical cork smoothness in a relatively cheaper way of processing. The stripes are often cut from the leftovers of the wine stoppers industry so there is no wastage of cork! On top of that, the direct use of cork bark means the trees are kept in a healthy state and promotes the preservation of cork oak forests (montado) throughout Portugal and Spain.

Cons: The stripes joint together and the many natural pores cut horizontally means that for thinner cork products these could break apart at these parts. As it is cheaper to produce and widely available, many unethical businesses based in third world countries are making products with these process by the millions. Unfortunately this kind of fabric does not have the same kind of strength and leads to propagate the idea that cork is not a durable material. Adding to this the cheap backing and synthetic dies and is a perfect recipe for disaster at the consumers expense.

Main uses: Cork Floor Tiles, Cork Wallpapers. Some fabric uses such as towels or bed covers.

Not Recommended For: Durable Cork fabric. The many joints in the fabric and the pores themselves means the fabric will likely decompose from these parts and break away. Many cheaper cork fabrics made in unsustainable ways are sold in this way. The backing of these cork fabrics is normally a plastic mesh or sheet to cut costs. As a fabric it has a very low durability rate. It does not help either that it’s dyed normally with chemical compound. Chemical dies in a thin cork cut makes it dry up and break apart quicker.

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A pouch made of cork stripes fabric.

But wait, don’t you have some wallets and bags made in a similar style? Yes and no. Meaning yes we do, and no it’s not the same techonology. The Portuguese investment in Cork technology means that there’s new ways to process cork into stripes and other shapes ensuring it does not decay. This is done by ensuring that after the cut is made, a layer of natural plant based resin is added to the cork layer to ensure it won’t decompose. This will always be clearly identifiable as you won’t feel the joints and crevices on the cork fabric.

Cork Fabric

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Cork Fabric is created from cubes of cork cut directly from the bark or from the leftovers of cork wine stoppers processing.

The cubes are layed in 25 meters long by 1.80 meters sheets by hand and cut to 0.1mm thickness. This now layer of cork is then inserted by hand into a machine which binds it with a cotton baking. By pressing both layers together the cork releases a resin that effectively binds them into a waterproof and durable fabric. But the process is not over yet. Afterwards, skilled workers will cut by hand any irregularities in the cork fabric. The cubes cut in a vertical direction as opposed to the horizontal cut of cork stripes. Which means theres a lesser degree of porosity in the cork fabric itself. On top of that higher quality cork fabric is made of the less porous cork bark possible. And the lesser joints and pores means a higher degree of durability of the fabric itself. The backing is almost always cotton giving it an additional flexible strength to the fabric.

Pros: Cork fabric is the ideal for crafting and leather alternative. It takes color very well which means it can be crafted in different colors. it’s degree of flexibility means it’s an ideal natural fabric.

Cons: Being made of the highest quality of cork bark means it has a higher value but a higher durability as well. It takes only natural dies and attempts at using cheaper artificial colorants will damage the cork.

Main uses: Cork Accessories, Cork Footwear and even Cork Clothing. Also ideal for Cork Towels, Rugs and wallpapers.

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Not Recommended For: Industrial uses. Cork fabric can decay very quickly when in contact with some chemicals becoming brittle and breaking away. If you’re not sure on what to use on your cork product ask us first.

 

So in conclusion, what’s the best and most durable type of cork?

The most durable cork fabric will always be the one with the less pores and joints possible. The lesser parts that make the cork sheet, the longer it will last. The exception is if the layers where treated after the cutting process and this is easily identifiable by how the cork feels. It will feel like polished wood.

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