Fermentation Cap for Ball Canning Jars

thingiverse

This reusable food-grade cap is designed for fermenting vegetables in canning jars. It helps maintain an air-tight seal during the fermentation process to prevent spoilage. The cap fits Ball Canning Jars with glass lids and wire holders, and features a water chamber to create pressure inside as food ferments. To use, place the jar's lid on top of the food, then put this cap over it, filling the water chamber up to the breathing tube level. Allow a few weeks for fermentation. The creator recommends using a finely-tuned 3D printer and suggests applying weatherstripping or sealant to the bottom piece for an even tighter fit. Feel free to modify and use this design as desired; licensing information is unclear, so an open license has been used. Note that the brown liquid in photos is apple cider, not fermented food. Enjoy experimenting with different foods for fermentation!