Some of the most frequently asked questions we hear from the home winemaker are: What cork should I use? What is the difference in the types of corks? Which cork is the best? How long do I soak my corks before using?
Corks are a very important part of wine making since we want them to seal properly, not contaminate the wine, and not be a problem when it is time to remove them. All of these can be accomplished by using a good quality cork, proper handling and storing and most importantly, proper preparation before they are inserted into the bottle.
There are basically 3 types of corks you can use seal your bottles:
- Natural corks: Not the first choice of most home winemakers because of the cost and ability to find good quality.
- Agglomerate corks: The m ost common type used by home winemakers because of reasonable cost and excellent quality.
- Synthetic corks: Plastic, fairly expensive, but have been known to leak on occasion. Cannot be used with most hand corkers due to the density of the cork.
Commercial wineries buy their corks in large quantities packaged in bags filled with SO 2. The corks are placed directly into the cork hopper with minimal handling and no sanitation required. Home winemakers buy our corks in much smaller quantities and therefore they are handled at least once when repackaged in bags of 30 or 100. No SO 2 is added to the bags for protection. Since they are repackaged and handled along the way it is best to sanitize your corks before using. Let's look at some of the best ways to handle, store and sanitize them before using.
Over handling agglomerate corks can cause issues with "tight corks" that are difficult to remove. This is because they are coated with an inert food grade compound and this coating can be rubbed off by excess handling. Removing only the amount of corks needed for your current bottling session is best and will help prevent handling the same corks multiple times. As with sanitizing everything that touches your wine, we need to keep this in mind when handling our corks. Wash your hands well, make sure the corker is clean and have a clean place to set your corks when using.
The bag your corks came in is good for storing any used ones until you are ready to bottle your next batch. Close it as tightly as possible and store them away from excess moisture, heat and dusty or dirty conditions.
Extended soaking or excess rinsing of your corks can also contribute to "tight corks" in the same way over handling does. Many older books may even instruct you to boil your corks. This should never be done, especially with agglomerated corks. If using natural corks or agglomerated corks that are less dense than the Fine Vine Wines Perfect Agglomerate, there is another risk from excess soaking. It can activate spoilage organisms in the channels and pits. I know you are thinking that if I am using a sulfite solution this shouldn't happen. After the sulfur dioxide gas dissipates, the remaining liquid can activate bacteria and carry it out of the cork and into the wine as it ages.
Here are two methods that will help you sanitize your corks without over handling or excess soaking to help avoid the issues mentioned above. To sanitize your corks using either of these methods use the standard 1.25% sulfite solution with either Potassium Metabisulfite (K-Meta) or Sodium Metabisulfite (Na-Meta). To make a 1.25% sulfite solution, mix 3 tablespoons of K-Meta /Na-Meta with 1 gallon of cool water.
Count out the amount of corks you will need and place them in a clean colander. Purchasing a new colander for this method might be a wise investment. Place the colander in a bowl and pour your sulfite solution over the corks and into the bowl. Cover the colander with a plate to trap the SO 2 gas and allow the corks to drain into the bowl for approximately 5 minutes before using so they are just damp and not wet.
This method addresses all the potential issues with over handling, sanitizing, and long term storage if your purchase corks in bulk.
You will need a sanitized plastic bucket with a lid that seals well, an empty wine bottle or other suitable open container. Fill the wine bottle halfway with 1.25% sulfite solution and carefully stand it up in the bottom of the bucket. Gently pour your corks into the bucket, filling the space around the bottle, and put the lid on tightly. Leave the bucket in a room temperature area for about a week. During that time, the liquid in the bottle or open container will raise the humidity in the bucket and increasing the moisture of the corks. The sulfur dioxide gas that fills the head space of the bucket will prevent the growth of spoilage organisms, keeping the corks sanitary and ready to use. No further treatment of the corks will be necessary before bottling. For long term storage of your corks replace the solution in the bottle every 3-4 weeks, and keep the lid tightly sealed.
By following proper techniques with handling, storage, and sanitation of your corks you can prevent problems and spend more time enjoying a glass of wine!
Scott Irwin - FVW Editor and Technical Creator