All of the flavors and deep lush colors found in red wine come from the skin of the grape.  These prized, but sometimes elusive flavors and colors are extracted during the fermentation process.   So a critical component in making deeply colored, flavorful red wines is to keep the juice of the grapes in contact with the skins.  As the grapes are fermenting, the yeast turns the sugar into alcohol and creates carbon dioxide which pushes the skins and seeds (the “cap) to the top of the fermentation bin.   A daily task for the winemaker or her cellar rat is to push the floating cap of grape skins back down through the juice.  The job of “punch down” is done at least three times a day during the fermentation period.  And hopefully no one falls into the fermentation bin.