For our Shine Remineralizing Tooth Whitening Powder (both the jars and the bulk bags), our production team gave unopened containers of Shine about a 3-year expiration date based on their product knowledge (the date is printed on the bottom of the jar or the back of bulk/refill bags).
Once you’ve opened a container of Shine, we suggest using it up within about 6 months of opening it.
The trick to having any container of Shine last is to keep moisture out of it so that the powder stays nice and dry and clump-free. So for example, after opening a jar of Shine, we recommend removing the wooden spoon and storing it outside of the jar, as wood can hold moisture. And always keep containers of Shine closed between uses.
For folks who live in humid places, it’s recommended to store flour in an airtight container in either the refrigerator or freezer (since Shine is also a powder, if you live in a humid environment, you may find benefit from using similar flour storage tips for Shine). If this speaks to you, then feel free to try putting your entire container of Shine into a resealable baggie or other airtight container and store it in the fridge or freezer.