The Fermentools fermentation Lid is the genesis of the entire product. Made of 304 stainless steel, also known as food grade or surgical steel, it will last a lifetime. Stainless steel is extremely corrosive resistant and very tough; it will withstand excessive abuse and still retain its shape. You will not accidentally bend these lids because the material is so much thicker and tougher than standard Mason jar lids. Just about the only way you’re going to be able to abuse these lids is to pound on them with a hammer, or go at them with pliers in both hands.
Simply punching a hole in the center of the lid causes shavings from the stopper to fall in your ferment and shortens the life of the stopper. Instead, I extruded the center in a 10° angle. Ten degrees produces a locking taper, the same taper the #2 stopper has. The locking taper has been used in the machine trades and laboratory settings for over a century. The taper will wedge and create an excellent seal. In addition to the superior seal, you’re also able to install and remove the stopper numerous times without causing it any wear. The 10° extrusion in the center of the lid also adds extra strength; you will not accidentally bend these lids.
The drawback to adding the 10° extrusion to the lids is the difficulty in the manufacturing. As mentioned, stainless steel is extremely tough and does not form easily. In order to create this taper, we punch a hole before starting the extrusion. With the extrusion started, the material will start to “work harden,” and then needs to be annealed for softening—individually, not in batches. After annealing, the extrusion process is completed. The additional steps are costly. But since this is a once-in-a-lifetime expense, the additional cost is worth it. The end product gives you a rigid, durable lid that will last a lifetime. I firmly believe that this fermentation lid is the best one you will find on the market today, and the only one made from stainless steel. This what it takes to turn your standard mason jar into a fermentation jar, replace any fermentation crocks you may have on hand.