During fermentation, the massive production of carbon dioxide sends the skins and stems we leave in red wine ferments floating to the top (pictured left). All those elements have goodness that we want to extract from them and as a result we need to work to submerge and mix them with the warm Syrah, or Pinot, or whatever it is. One could use a pump to pull from the bottom of a tank and spray the wine over the skins, or one could “punch down” the stems with a long plunger. We do both.
Standing above the fermentation you simply work to puncture the “cap” floating on top and submerge all those great skins. During the peak of the fermentation this is much more difficult than toward the end when the carbon dioxide production as slowed considerably. We have also posted a video here of this process.