Eli5, why do Mason jar lids typically come in 2 parts, threads and seal, as opposed to nearly every other commonly used household container?

Question

Eli5, why do Mason jar lids typically come in 2 parts, threads and seal, as opposed to nearly every other commonly used household container?

In: 7899

Answer 1

TL;DR – the sealant coating on the lid is really only single-use; it’ll never work well a second-time around.

Since mason jars are _intended_ to be re-usable over and over; however the act of sealing the jar + food residue may deteriorate the sealing coat on the bottom of the lid – and then they don’t seal as well and maybe that jar spoils. Wheras, unless you’re not careful with the “rings” (leave food residue on them, let them sit in water and they rust), they’ll last a long time, so you can reuse the rings over and over. So each time you re-use a set you use new lids, reuse the jar and ring. Its a bit cheaper if you’re a serious canner/preserve maker as you can buy the lids in bulk for not a lot.

I don’t can/preserve but a lot of my family does and I get the benefit – so I always have a collection of mason jars in my cupboard for re-use. However if Im storing leftovers, Ill actually use single-piece lids from sauce jars (Prego lids fit nicely) on my mason jars so Im not always burning new mason jar lids everytime I seal something up that I intend to be opening frequently.