parable of the patch and wine skins in scripture

If they are used again for holding wine that is still in the process of fermenting ('new wine'), they will burst. However, skins that have already been used and stretched out ('old wineskins') cannot be used again since they cannot stretch again. If one puts freshly pressed must directly into the skin and close it off, the tumultuous stage of fermentation would burst the wineskins, but after this stage, the skins have enough stretchiness to handle the rest of the fermentation process. The skins were filled with must (partially fermented wine) in the opening at the neck and then tied it off.

The wineskins were partially tanned goat skins, sewn at the holes where the leg and tail had been. Then the must (fermenting juice) was put in clay jars to be stored, or into wineskins if it was to be transported some distance. Fermentation starts immediately on pressing, and this allows the first 'tumultuous' (gassy) phase to pass. In ancient Israel, the grapes were pressed in the winepress and left in the collection vats for a few days. Summarizing Hastings Dictionary of Christ and the Gospels entry on wine bottles:

Parable of the patch and wine skins in scripture