At this stage, the yeast organism is destroyed by the alcohol it has produced and fermentation ceases. This is what is known as a natural wine. Most commercial products come under this category until they have been fortified. This period of fermenting in the tub can be a dangerous time. Because of this, the fermentation process should be completed as soon as possible (even at the risk of losing a little of the wine's bouquet).
Next, we must then keep the brew warm. Our goal here is to bring about ideal conditions in which the living organism and yeast cells can multiply more rapidly. Warmth helps to ensure this. The faster they multiply, the more rapidly they convert the sugar into alcohol and therefore, the sooner the yeast destroys itself.
Do not be tempted to keep a brew hot during fermentation. During warm weather, any odd spot will do for a fermenting brew. Also, a warm spot in the kitchen or in an airing cupboard is as good as any during the winter.
After 14 day of fermentation in a warm place, the wine can be bottled or put into stone jars. This is the time to add the isinglass.When put into wine, isinglass forms an insoluble cloud which surrounds the minute solids in the wine and gradually forces them to the bottom of the bottle.
Besides assisting the clearing process, isinglass helps to solidify the lees, thereby rendering them less easy to disturb while moving the bottles or when wine is poured from a bottle containing lees.