All Vintage Ports will develop some sediment through the years, and slowly deposit these on the inside of the bottle with ageing. Since they are bottled at a young age, Vintage Ports slowly change through the years, maturing, softening, and developing that unique complexity we so enjoy. Some of the sediments may form a "crust" on the inside of the bottle, and still cling to the glass even after decanting.
Required for the task are some simple tools -- primarily a reliable light source and a suitable and clean decanter. The idea is to allow the sediments to deposit on the bottom of the bottle, and then carefully pouring the clear wine off, separating it from and leaving the remaining sediment in the bottle. With a little attention to detail this is easily done, and with some additional flair, it can become quite an impressive tradition.
The light source can be anything from a candle to a small flashlight stood on end or supported in a small glass. The decanter may vary in shape, but should be big enough to hold the entire contents of the bottle. Make sure it is clean and dry.
Most wine is stored laying on the side or upside down, both with the neck and cork of the bottle in a lower position to retain some moisture in the cork and maintain the seal. For decanting purposes, we will require the sediment to be on the bottom of the bottle as it stands upright. Consequently, it is important to allow enough time for the disturbed sediment to re-settle in that position. Place the bottle in a convenient location, standing it upright for at least overnight, if possible.
When it comes time to decant, be careful not to suddenly move, tilt, or jar the bottle when removing the cap and cork. All of those actions may stir up a bit of the sediment and some of the clear Port may become slightly muddy. The bottle may be moved to a serving table for decanting, but be careful to keep it in the upright position.
The light source allows one to see through the neck of the bottle and determine at what point sediment from the bottom begins to flow through the neck indicating that the decanting is done. As you begin to pour the Port into the decanter, it is important to remember that it should be done in a slow and continuous motion, without tipping the bottle back and forth as in pouring wine into various wine glasses. This tipping motion will "slosh" the remaining Port in the bottle, and of course disturb the sediment that has settled on the bottom. When sediment begins to appear in the neck of the bottle when pouring, tip the bottle back to an upright position, and the decanting process is complete.
At this point, you may serve the Port in individual glasses, poured from the decanter. Of course, the bottle may be passed around so that everyone may inspect the label. By using a candle and perhaps a crystal decanter, there is a certain elegance associated with the opening and serving for your guests.
I have used the flashlight in a glass when decanting in the laboratory, but prefer the traditional candle for the simply stated elegance. Allow this traditional ritual to become a part of your Port enjoyment!