It is often recommended that wine makers soak or even boil corks prior to bottling. Is this really necessary? Let’s take a look.

Why Some Recommend Soak and / or Boil Corks

Boiling wine corks is a bad idea. It ruins the cork and leaves you in danger of ruining your wine.Soaking corks came about as a way to clean the dust off of new corks. However, even back before pre-sterilized corks were available corks were not soaked for very long. Somewhere along the way some wine makers decided that this is a necessary step during the bottling process.

Long soaking times, however, allow the cork to absorb whatever liquid it is submerged. That liquid can then be squeezed out of the cork when it is inserted into the bottle. Anything that comes out of the cork at that point goes into your wine.

Boiling corks likely came about as a means to ensure the corks were sanitized. This would be a great way to sanitize corks without using chemical, however, boiling corks can seriously damage them and make your wine more susceptible to problems.

Why You Should Never Soak or Boil Corks

Soaking corks does two things. First it allows the cork to absorb the water and any other chemicals mixed with the water. Also, it allows the cork ample time to be exposed to contaminants and micro-organisms.

Most of the recommendations I’ve seen for soaking a cork involve letting them sit in a bowl of water for upwards of five or six hours. That’s a long time to leave your cork out there exposed to everything.

The only proposed benefit is that the cork goes into the bottle easier. While this may be true it could go in a little too easy. A soaked cork may go too far into the bottle, possibly ending up all the way past the neck.

As I mentioned earlier whatever you soak your cork in will get squeezed back out again when it’s inserted into the bottle. Adding sanitizers directly to wine just doesn’t seem like it would be good for flavor.

Boiling corks is the worst thing you can do to your closure. The high temperatures actually melt off a coating that is placed on corks to reduce cork dust and to help them stick to the inside of your bottles.

Without this coating the water penetrates the cork and can actually hydrate dormant molds and bacteria that occur naturally in cork. Now instead of the corks being sanitized they may actually have been turned into a great place for micro-organisms to grow.

What do Professional Wine Makers Do?

Professional wine makers do not soak or boil corks. They insert dry pre-sterilized corks just like the ones you can buy at your local wine making supply shop. Pre-sterilized corks are sealed in air tight bags to keep them in pristine condition until you’re ready to bottle.

Granted wineries are likely using something a bit more powerful than a hand or floor corker unlike amateur wine makers so they will have an easier time inserting them. However, their handling of cork closures is something to take note of.

Wines produced by a winery will often be in the bottle for many years. The integrity of their corks is a huge concern for them. They trust that the corks they purchase are sterile and ready to be used. They’re staking their entire business on it.

My Recommendations

  1. Purchase corks that have been pre-sterilized and are packaged in sealed bags. This ensures that you’re getting a clean product to begin with. These are the corks I use (affiliate link).
  2. Open your bag of corks right before bottling. This minimizes their exposure time so they won’t pick up a bunch of micro-organisms. Until you need them keep them in the sealed bag.
  3. If you really feel like your corks need to be sanitized just give them a quick dip in a Star San solution. Thirty seconds or so at the longest is fine. I’ve done this in my earlier wine making days at the recommendation of a local wine making supply shop and had no problems (this was before doing this research).

Never boil corks. There are just too many risks.

Photograph by: Jamie