F Pack
I believe it stands for "Finishing Pack", but I like "Flavor Pack" better as mentioned in this thread. For us, this is where the fun of winemaking is, that is using your own creativity to flavor and sweeten your wine to your own tastes.
You can make your own by simmering fresh grape or friut juces down to a concentrate for a couple hours. Careful not to scortch the juce.
Or you can use ingredients you can buy at the wine store Example: Last year we made a wine we called "Blackberry Blush". We did a simple Blush Wine Kit, and when it was done and ready to bottle we made our own F Pack that consisted of 16oz red grape concentrate and 4oz blackberry wine/beer flavoring, which we purchased at the wine store. To that we added two ticks or what we call a tick (one tick=2cups sugar disolved in 1cup water) Of course add sorbate to prevent refermentation.
Of course to us making good wine is like making a good pot of chili. the best bowl of chili is the last bowl you heat up. And with wine the best bottle we drink is the last bottle of a good batch where we say "I wish I had another bottle of this'
This aged really well, and turned out better than we expected: semi sweet with good body and flavor.