We have been selling a lot of tapered or conical corks recently in both agglomerated and natural cork. Generally we do not work from stock and for orders of the larger conical corks we can make up orders of just 1000. There is a sizing system for conical corks which is detailed below. Generally we can produce an order in less than two weeks and we can make sizes outside of those detailed below.
|Size No.||Top mm||Bottom mm.||Length mm||Size No.||Top mm||Bottom mm.||Length mm|
Five to ten years ago there were various people declaring that the cork industry would be largely consigned to history as screw caps take over from cork stoppers for wine bottles, but in fact over recent years corks have been increasing their share of the market rather than losing it. The truth is that the major players in the cork industry had become complacent and the threat of screw caps and even plastic stoppers precipitated a spate of innovation which has left the cork industry in a much stronger position.
Going into a cork factory now you see a lot of changes from what they would have looked like ten years ago – one of the big changes is that you see serious looking people with clipboards and white coats walking round; these are the lab staff who control quality and who have been largely responsible for virtually eliminating TCAs (the chemicals from corks that can taint wine) from cork production, by introducing new treatments and dramatically improving quality control.
The other major difference in cork production is that technical corks have become a major part of the wine stopper market. Technical corks in their most common form (known as 1+1 corks) consist of an agglomerated cork body with a natural cork disc on each end. So the wine only comes in contact with natural cork (rather than agglomerated cork and the synthetic adhesives that this contains) and the user sees natural cork whilst the cork is still in the bottle, making the appearance much more attractive.
The technical corks are much lower cost than natural wine corks (for example, depending on quality they may cost say 60 euros per thousand rather than 120 euros per thousand for natural wine corks), but they have many of the benefits of natural wine corks. So although they may be a little more expensive than screw caps they are a compelling alternative, because not only do they lend the wine the quality feel that natural corks give, with the vastly improved quality control that corks come with nowadays, they also give the winemaker total security that their wine will be safe inside the bottle.
Expanded cork (or black cork) is made from the bark of the cork tree that is of too poor a quality to be used for making natural wine corks. Principally this is from branches that are pruned from cork trees (see photo below), fire damaged cork from forrest fires and ‘virgin’ cork (the cork that come from the first harvest of a cork tree that does not have sufficient density to be used for wine corks). This lower quality cork has high quantities of resin in it, which is a key ingredient to the process (see below).
Because the cork that is used to make expanded cork is of lower quality, it typically contains a relatively high percentage of wood and dirt; so it is ground down to granules of approximately 20mm and the cork is sorted from this wood and dirt (the wood is then used to heat the furnaces to produce steam, used later on in the process). It then is placed in moulds (typically 150cmx120cm) and steam heated to 400ºc is passed through it. These high temperatures encourage the cork to liberate the resins it holds and for the cork itself to expand and after two hours the granules are bonded together by the naturally occurring resin to fill out the mould to form a block (see photo). These blocks are then left to cool off and stabilize before they can be processed.
These blocks can then be cut into different dimensions according to the end usage – generally they are cut into boards of 1000x500mm with thicknesses of between 10mm and 150mm. These cork boards can then be applied directly to be used for insulation of buildings (for more information about the acoustic and thermal insulation properties of expanded cork click here), or they can be cut and shaped using CNC machines or normal saws and then sanded down to make decorative items, such as the stools, chairs and tables shown below. When expanded cork is used to make decorative items, sometimes it is necessary to produce the cork at higher densities to make the products more durable. Any excess granules of black cork that are generated by cutting and shaping can then be sold to be mixed with concrete to produce an ultra-lightweight concrete filler.
One of the great things about black cork is the fact that it is a great use of resources, as it uses up cork bark that would otherwise not be usable, it does not require any trees to be cut down for its production and the process itself generates the fuel to power the furnace, so fossil fuels are not necessary. As well as all of this, expanded cork is one of the best natural and acoustic insulation materials that exists as well as being attractive to look at. Please contact us if you would like to find out more about sourcing expanded cork direct from Portugal.
In recent years there has been a lot of development in using cork agglomerate in innovative ways, by mixing different kinds of corks granules, adding colours, varying the densities and so on. The main way that this is done is to add cork granules and adhesive into a block mould, then to apply pressure. What emerges is a block typically 640x940x200mm that can then be cut or laminated into whatever size is required.
In the image you can see an example of the kind of thing that can be produced. To make this block, we used the shavings that are produced as a by-product when natural wine corks are trimmed down to size. These were mixed with a food-grade adhesive and split into two batches where different coloured dyes were added. The mould was then filled with layers of the two colours and compressed and this is what was produced.
Using this technology we can produce a broad range of densities and all manner of different appearances (for example by changing granule size, using expanded cork, untreated natural cork and so on) and a wide variety of densities depenending on the final use. These blocks can also be laminated to produce sheets that can be used for decorative purposes, such as wall coverings or flooring. We are also able to produce moulded cork products using custom moulds that can produce more or less any shape. Generally to use this 3D cork moulding technology, the mould itself would cost from €2500 upwards, but then the individual moulded cork products produced would be relatively inexpensive. If you would like to know more about this process, please contact us at CorkLink.
1+1 corks are made from an agglomerated cork body with natural cork discs glued on to each end. So natural cork will be displayed to the consumer when about to open the bottle and will also be in contact with the wine in the bottle.
Agglomerated cork is a good deal less costly than natural cork, so by just using two natural cork discs rather than an entire cork made from natural corks, prices are reduced dramatically (typically a 1+1 cork will cost less than half than a natural cork, depending on quality). For wines that are going to spend less than 4 years in the bottle, they are a good solution, as although they will not provide such a good seal as a full natural cork, the disc at the bottom of the cork will seal the bottle effectively (better than a 100% agglomerated cork would).
Although the majority of technical corks sold are 1+1 (that is with one natural cork disc at either end), there is also available 2+0 (two natural cork discs on one end and none on the other) and 2+2 (two natural cork discs on both ends). The discs are graded either A, B or C and in the photo you can see from left to right examples of A, B and C corks – if you click on the photo to magnify it, you will see that the surface of the A grade disc has far fewer imperfections than the C grade disc).
The standard sizing is 44×23.5mm and an indicative price per thousand would be around 55 euros per thousand, depending on the grade and volumes. If you would like us to quote you for your requirements or would like to see some samples, please get in touch with us at CorkLink.
Expanded cork was developed in the mid 1990s to provide a 100% natural insulation material, using parts of the cork bark that were not previously used. When the cork oak tree is stripped of its bark, generally only the trunk is stripped and the upper branches are left untouched. The cork bark from the upper branches cannot be used to make natural corks, as it is not thick or uniform enough and contains too much resin.
However this upper branch cork can now be used to make expanded cork, which makes use of the naturally occurring resins to bind granules under pressure without using any additional adhesives. Once this cork has been stripped from the tree, it is made into granules, which are placed in a mould and compressed. Then super-heated steam is added to reach temperatures of up to 370ºc for 20 to 30 minutes, which causes the resin held within the cork granules to come to the surface. this resin now becomes the adhesive that binds the granules together – meanwhile, the heat also causes the granules to expand. What is left is a block of expanded or black cork, which can then be cut into boards of varying thickness (generally 10mm to 300mm) with a density of between 105 and 125 Kg/m3.
This expanded cork is much darker that normal cork because of the resins and it also has a distinctive resinous odour that fades over time. As well as being 100% natural and recyclable, expanded cork is a fantastic insulation material as the expanded cells contain 50% air and are also waterproof and fireproof.
The technical characteristics of expanded cork are:
Thermal conductivity coefficient – 0.040 W/m.K
Density – 105-125 Kg/m3
Tension to stress – 1.4-2.0 KGf/cm2
Functional temperature range – -180ºc to +140ºc
Fire class – Euroclass E
The main applications are for exterior walls or double walls for acoustic and thermal insulation, but it can also be used under paving slabs (for noise reduction) and for thermal and acoustic wooden panels and a range of other insulation applications. Please contact us if you require any further information or would like a quotation.
The production techniques for premium natural corks have been revolutionised in recent years to guarantee negligible levels of contamination and extremely reliable quality control. So if you buy natural corks from a supplier such as CorkLink, you can expect to receive an extremely safe and reliable product. However it is important that once you receive the corks, you should handle them correctly, to avoid any risk of contamination or deterioration:
- We deliver corks in sealed bags containing sulphur dioxide, so do not open these bags until the corks are ready to be loaded into the corking machine.
- Do not leave any unused corks in the corking machine, but return them to the bags until they are next required.
- Always store corks in a cool dry area, away from any other chemicals. The ideal humidity level to store corks is 50 to 70% and the moisture content of corks themselves should always be between 5 and 8%. It is also important to make sure that the bottle necks are also completely dry before corking.
- You should use natural wine corks within 6 months of buying them – after 6 months, there may be some deterioration in the mechanical properties of the corks and they may require a fresh treatment.
- The temperature of the wine at bottling should be between 15ºc and 21ºc (50º to 70º Fahrenheit) – if for any reason the temperature is lower than this, the wine may expand in the bottle when it warms up, which will decrease the vacuum space in the bottle. The bottles should also be kept upright for 24 hours after corking.
- Finally it is worth reiterating how important it is that you use an appropriate cork size for the wine and bottle type you are using. We are always happy to offer guidance on this, but you need to consider the profile of the neck of the bottle you are using and how long the wine is going to age in the bottle when considering the length of the cork that you are going to use.
We go to enormous efforts to make sure that the corks we deliver are in perfect condition, so it is always worthwhile to make sure that you do everything you can to keep them this way by following the above rules. If you would like to know any further information about looking after natural wine corks, please don’t hesitate to contact us.
Over 70% of the world’s wine corks are made in Portugal and the percentage is quite a lot higher than this for natural corks and other high end corks. If you are looking for a new wine cork supplier, then Portugal is the natural place to look, but choosing a supplier is very difficult.
The cork industry structure has changed a lot over the last 10 years or so – from being an industry dominated by one supplier (Amorim) and then three to four hundred small suppliers, there are now a handful of medium and large suppliers and far fewer small ones. In short, the industry has matured and consolidated.
Furthermore, over the last ten years, a few medium sized cork suppliers borrowed heavily and increased their capacity and production quality dramatically to become big players, but most of these got caught out when the price of cork fell over recent years and because they were in massive debt to the banks, they could not survive.
Now the industry still has Amorim as the largest supplier, but there are a small number of large wine cork suppliers that can actively compete with them as well as a number of niche players. Unfortunately there are still a few companies around that sell corks at lower costs without the kind of quality control that wine producers only find out about a few years down the line when clients get round to drinking their wine….
There is no getting round the fact that to producer quality corks requires significant investments in laboratories, stock control, R&D, advanced production techniques and so on. At CorkLink we are focused on providing the best quality corks available on the market at reasonable prices; by allowing our international clients to source direct from Portugal, we can cut out local distributors and offer cost savings without compromising on quality. If you are a wine producer interested in buying corks from us, you would be very welcome to come and visit some of our production facilities or please ask if you would like to see some samples.
We supply a lot of custom Bar-top or T-Top corks (also known as capsulated closures) – we can make most specifications that clients require and we can provide a wide variety of custom options.
More and more spirits manufacturers are opting for micro-agglomerated corks, which are fine for non-premium products, but is seems a real shame for premium brands to save a few euros on their closure by not opting for natural cork: whilst micro-agglomerated cork can provide an effective closure for spirits bottles that are kept upright and not stored for years, a natural cork conveys quality rather than the more synthetic look of micro-agglomerated.
We do have a wide variety of moulds (molds in American) for standard capsules in either plastic, wood or even metal, glass, cermamic or agglomerated cork, but we are always happy to make a mould up specific to a customer. Whilst customers are generally comfortable with the kind of capsule that they require, choosing the best cork is more difficult.
We always prefer to see a sample of several bottles so that we can recommend the cork dimensions – glass bottles typically have a fairly wide tolerance so we need to sample several bottles before we can give our recommendation. We will take you sample bottles and analyse the neck profiles to within fractions of a millimetre and then we can stipulate the maximum and minimum cork length and diameter that we would recommend – it then comes down to customer choice whether they prefer a tighter or looser fit to the cork stopper.
If you have any questions or require a quotation for your Bar-top corks, please don’t hesitate to get in touch.
Some of our clients like to buy their corks together with the capsules and we are of course very happy to supply this. We can supply PVC capsules, polylaminate capsules and tin capsules with pretty much any colour and graphics you may require.
Polylaminate capsules are an effective lower cost alternative to tin capsules, as they have a more robust feel than PVC capsules and are easy to customise in terms of adding tear strips, perforations, embossing, hot foil stamping and carry graphics well. They are made from three layers: aluminium / polyethylene / aluminium and then an aluminium top disc, which makes them strong but easy to fit.
If you would like to have a quotation for your capsule requirements and would like to buy direct from a capsule supplier in Portugal, please get in touch with us at CorkLink.