Choosing and Using Corks

Wine Cave Inc. sells a variety of corks. For most kit wines we recommend an economy grade cork, as it will have the combination of quality and value that best suits wines to be kept for up to 6 months. For wines intended to be kept longer we recommend a winery grade cork: slightly more expensive, but with a higher density and less potential flaws, it will keep the wine for 1 - 2 years. For the best wines, made from premium juices and grapes, investing in the top grade of premium corks will pay off over time.

But what about cork length? Should you choose 1½' or 1¾' ? Will a longer cork keep the wine longer? The answer turns out to be more subtle than first glance would indicate. How well a cork seals a bottle depends on three things:

1. Cell Density.
   This is the most important factor. If the cells which comprise the structure of the cork are well formed and sound, a layer 30 cells thick (less than ¼') will stop all movement of wine. If the cells are less than optimally arranged, it can take more layers to prevent leakage. Corks are graded partially on cell density, with the most dense also being the most expensive.
2. Potential Flaws.
   The presence of pits and areas of uneven density is common to all grades of cork, but again, the most expensive will have the least number of these, and thus will seal more effectively against the neck of the bottle.
3. Contact Length.
   There are two principal bottle shapes used for wine, the Bordeaux style and the Burgundy style (there are others, but they are less common). The difference between the two is the amount of flaring in the neck. Bordeaux bottles have a relatively straight sided neck throughout it's length, while a Burgundy bottle will flare dramatically after about 1½'

This flaring means that the last ¼' of a 1¾' cork will not be in full contact with the bottle neck (with pitting and low density it can't expand enough to fill any flaring beyond the standard 11 mm.), thus wasting it's ability to seal the bottle effectively. The best choice for Burgundy style bottles will usually be the 1½' cork, and the length of time the wine will be kept will determine the grade needed.. Quality is more important than length for determining which cork you should use.

But, if a 1¾' economy grade cork isn't substantially better than a 1½', is a 1¾' winery grade cork better than a 1½'? The answer is a qualified yes. Because it has higher cell density and fewer potential flaws it can fully expand to exploit it's sealing power along the full length of the bottle neck. While this increased capacity is more dramatic in Burgundy style bottles, the increase in sealing power applies as well to Bordeaux style.

Premium corks are designed to keep the wine for 3 to 5 years, or longer, given good cellar practices. They also have a price tag to justify their quality—they may not be the best choice for any wine being kept for less than three years.

The table below provides a rough guide to how long your corks will last, given proper handling.

Length	Agglomerated	Economy	Winery Grade	Premium
1½'	6 Months	6-18 mo. 18 mo.-2 years	3+ years	-
1¾'	-	-	2-3 years	3+ years

 

Handling your Corks

A lot has been written on how to treat corks at bottling. Much of this information was correct, but did not take into account the type of corker being used. Old-style compression corkers use a plunger to force corks through a funnel-style opening into the bottle. While they will push the cork in, they aren't very accurate, and require that corks be soaked and softened to allow them to slide through the small hole. This soaking can soften the corks to the point that they become mushy, causing them to disintegrate at a later date, or not to properly seal the bottle at all.

If you are using an old two handle or single handle compression type corker, you can soak your corks in the following solution: For every 4 litres of lukewarm water, ½ teaspoon of sulphite powder, about ¼ cup of glycerine. Soak for about 20 minutes, and then remove the corks to a sanitized bucket. The sulphite will sanitise the corks, and the glycerine will serve to lubricate their passage through the corker.

Newer iris-jaw type floor corkers (Wine Cave Inc. sells them as 'Mini Floor Corker' and 'Deluxe Brass Jaw Floor Corker') are precise and powerful, simultaneously squeezing the cork down and pushing it into the bottle with a leverage arm. They only require that a cork be sanitary before insertion. If you are using an iris jaw corker rinse the corks in your sulphite solution, and then remove them to a dry, sanitised bucket: no soaking, no glycerine and no rinsing needed.

After the bottles have been corked, it is important that they be kept upright for two to three days. This allows the air trapped underneath the cork to gently move past it, reducing the pressure in the bottle. If the bottles are laid on their sides right away, the pressure will not be released, and the wine pushing against the cork could force it out of the bottle.