The Safety Reason Mason Jar Lids Have 2 Pieces

Mason jars are the perfect containers for lunches, so it's nice to have several around, but if you're like me, you might be storing food in your jars all wrong. You also might struggle to keep them stored because the lids are in two pieces, and I've personally had mason jar lids scattered all over my pantry. Or, you might have noticed that industrially made jarred goods (jams, pickles, etc.) have lids that are one piece. So, what gives?

Turns out there's a very good reason: one-piece lids are good for industrial canning and food preservation because they have strict temperature controls in place. For home use, they tend not to work so well because they can leave air in the jars. Leftover air, as any experienced home canner can attest, will result in spoilage and bacterial growth. Instead, the jar lid is in two pieces: the ring, or rim, and the actual sealing top. The metal lid also has a compound around it that, when properly heated, should soften and then form an airtight seal around the jar. This ensures that no air and airborne bacteria or yeast can get into your homemade jarred goods.

Even though it's no longer 1858, when the Mason jar was patented, canning, pickling, and preserving fruits and vegetables at home is a wonderful thing to do. Luckily, it's not a necessity, but something done as a hobby, but it's still important to follow the manufacturer's instructions on using mason jars for canning. 

Even though we don't really have to worry about quite as many diseases as before, keeping your mason jars sanitized is a must. It's pretty simple; giving the jars a bath in water that's at a rolling boil is an excellent way to sanitize them. Leave them submerged in boiling water for 10 minutes; however, if you live above 1,000 feet, add 1 minute per every 1,000 feet in elevation. Just remember not to sanitize the seal part of the lid this way, as it will ruin it. While the mechanics of home canning and home jarring affect when and how to sanitize your jars, sanitizing them out of an abundance of caution is always a good idea.

One last thing to know is that you should never reuse mason jar lids from batch to batch. That seal on the lid I mentioned earlier, that softens when heated? Well, that's only good for one time; however, the ring part can be reused. Reusing lids will result in a dramatically increased chance of spoiling your jarred goods. Luckily, they're cheap and easy to replace!