After fermentation is done and the wine is blended for filtration.
Most wines go through cold stability and heat stability. They can be accomplished in a couple different ways these days. This is the old school method of cold stability, its easily accomplished by cooling the wine down (-4) and letting the acid precipitate out itself. Producers do it in the tank so your wine doesn't do it in the fridge.
This is an unfiltered, unracked tank of Gruner Veltliner. Still on lees. Every year, when you open the tank, the different wines, different acidities, give different effects.
This one reminded me of a city skyline at night, the outlines of the large towers, and a sky full of stars behind it.
It's not often I see this much build up and this much texture. I just had to take some photos. Hope you enjoyed them.
Cheers!