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Why Choose Cork For Wine Bottle Stopper

Nov 13, 2022

The cork seems to be a simple piece of wood, but its production method is as cumbersome as making wine. A good quality cork has a huge effect on wine, especially for expensive wines. Quality corks, why do wine corks use corks?

wine cork

1. Why do wine stoppers use corks?

The cork has the characteristics of softness and strong elasticity. It has many fine holes. When the bottleneck is sealed with it, the cork expands when it contacts with the wine liquid, which closes the gap of the bottleneck and prevents the wine liquid from leaking; At the same time, the wine can also contact a small amount of air through the micropores of the cork itself to achieve the purpose of breathing and development, and continue to complete its maturation process after bottling. In addition, the components of the cork soaked into the wine will also add structure to the wine.

It is said that before the wine was sealed with cork, there was no special wine cork. Usually, the container is first plugged with some vine grass and other materials, and then sealed with fire paint. There are many drawbacks in doing so: in the process of opening, it is inevitable that small particles of varnish and grass clippings will fall into the wine, thus affecting the hygiene of the wine; poor sealing will lead to serious oxidation of the wine, which will affect the quality of the wine; Liquid leakage is even more unavoidable, resulting in great losses.

2. Is it true that the longer the cork, the better the wine?

Generally speaking, the long stopper is a good wine, and they are all cork stoppers of whole wood. This wine has at least an aging potential of more than 8 years. If you drink it in advance, you must sober up. Because the long cork must be more expensive than the short cork, if the bottle is aged for a long time, the wine will penetrate into the cork, and the long sealing is more secure. This kind of long cork wine is mainly from traditional European wine-producing countries. And it doesn't need to be aged for a long time to drink, so there is no need to spend more money to use long corks. Usually, the length of cork used for general-grade wine is about 3.5 cm to 5 cm, and the length of cork used for relatively high-quality wine is more than 5 cm. For example, some French wines that sell for thousands of dollars use long corks. .

3. How is cork made?

The cork is made from the bark of the cork oak. The cork oak is a deciduous tree of the oak group, a slow-growing, evergreen oak that grows in some parts of the western Mediterranean. The cork oak has two layers of bark, the inner bark has vitality, while the outer bark can be peeled off without affecting the survival of the tree. The outer bark of the cork oak provides a soft protective layer for the tree, and it is also a natural insulating layer that protects the tree from fire; the inner bark is the basis for the new outer bark every year. The first harvest can only take place when the cork oak tree is 25 years old. But the 1st harvest oak bark is very irregular in density and size, not suitable for wine corks and is usually used for flooring or good insulation. After 9 years, the second harvest can be carried out. However, the quality of this harvest is still not up to the requirements of making cork stoppers, and can only be used to make ancillary products such as shoes, accessories and household items. By the third harvest, the cork oak was over 40 years old, and the bark from this harvest could be used to make cork stoppers. Since then, the cork oak will naturally develop a layer of bark every 9 years. Typically, the cork oak has a lifespan of 170-200 years, and it has 13-18 useful harvests in its lifetime.

The process from picking a cork oak to making a cork stopper is not simple, and it usually takes more than half a year. First, the cork oak bark is harvested by skilled workers from May to July each year. The weather at this time is hot and dry, which is conducive to the complete stripping of the thick bark. At the same time, hot and dry climates can occasionally lead to forest fires, so when harvesting cork oak bark, at least 35% of the bark needs to be retained to help the tree continue to survive. After harvesting, workers mark the year of the harvest on the trunk to ensure that each tree can be harvested at the correct time next time.

The peeled bark cannot be used immediately. It needs to be stored in the open air. The high temperature in summer is used to evaporate the water in the bark, and the tannin in the bark needs to be washed and diluted by autumn rain. After about 6 months of drying, the properties of the cortex became stable. The bark is then stored on concrete floors or on dry ground for further processing. After natural drying, the bark will be soaked and boiled in a covered jar. This process softens and cleans the bark, removing dust and some water-soluble substances. During the poaching process, workers regularly clean and filter the water used to cook the bark, and refill when necessary to avoid cross-contamination. After cooking, the bark becomes a flat and easy-to-work cork board.

After the initial cooking, workers grade the bark according to the thickness and fineness, remove the parts with low density and eroded by pests, and conduct a second fumigation to further remove the oak flavor of the wood. After fumigating the cork board for 1-3 days, workers can cut and punch holes. If it is a natural cork stopper, it needs to be completely cut directly from the plank, and it is completely hand-operated by skilled workers. Leftover boards can be made into cork chips, or ground into cork chips. These cork chips are sorted, bonded, segmented, tableted, smooth cut and polished to form polymeric cork stoppers.

After the cork is made, it also needs to be washed. Some customers will have color requirements, so some bleaching will be done during the washing process. After washing, workers will screen the finished cork stoppers to pick out products with surface defects such as fine edges or cracks. High-quality cork stoppers have smooth surfaces and small pores.

The manufacturer will print the words on the cork according to the needs of the customer, and do the final treatment. The printed information includes wine origin, region, winery name, grape picking year, bottling information or the year the winery was established. However, some cork manufacturers will ship the finished products to branches in different countries, and hand them over to specific customers for printing. In printing inkjet, mimeograph or fire printing technology is usually used. The mimeograph technique is less expensive, and the ink will seep into the plug and fall off easily. The cost of fire printing technology is higher, but the printing quality is good. Once printed, the cork can be used to seal the bottle.

4. How to identify damaged wine corks

Normally, corks are less prone to damage. As for how to identify whether the cork is damaged, you can check the infiltration of the cork to see if there is any infiltration, such as wine leakage, you can check whether there are traces of wine on the edge of the cork. In severe cases, even the top of the cork will There are traces of alcohol. If this happens, the wine may have gone bad.

It should be reminded that the wine should not be stored upright as much as possible, because the wine and the cork are not in contact, which will cause the cork to dry out, thereby losing its elasticity, allowing air to enter the wine and causing the wine to oxidize.

5. What is the harm of cork stopper?

According to the statistics of the French Bordeaux Wine Association, about 5% of the wine will deteriorate due to cork every year. It is equal to 5 bottles of every 100 bottles of wine that will spoil the whole bottle of wine due to the deterioration of the cork during the aging process, or the winery uses corks of questionable quality during bottling.

The biggest advantage of using natural cork is that it has natural pores that allow the wine in the bottle to breathe properly, but these natural pores are also an excellent place for mold to live and grow. If it is used without disinfection, or if it is stored in the bottle for a long time, it may cause the mold to grow and mix into the wine body, resulting in the spoilage of the wine. Even the residual sulfur dioxide and chlorine used to disinfect natural corks are also one of the important factors affecting the quality of wine.

In conclusion, the quality of the cork affects the quality of the wine, a well-structured cork is not airtight, it allows very little air to gradually enter the bottle. High-quality wines will use natural cork stoppers. The higher the grade of the wine, the longer the cork used.

Our team has 15 years experience in this industry, and our products were exported to more than 30 countries in the world. The misson of our team is to be a professional solution provider with a systematically resources and related know-how which comes from our long-term practice.