While electronics shelf life can be rather complicated (see some posts in the list below), what about the items that can aid one in extending shelf life by detecting environmental factors? This post is about humidity indicator cards. While there is a chemical reaction between moisture in the air and the chemical inside the cards, it doesn’t always mean that chemical will necessarily be ineffective over a long period of time. There are proper handling procedures recommended by the manufacturers for these indictors, though. Mishandling can result in improper function.
Example Part Number
SCP538-ND (4HIC100) from SCS is a generic humidity indicator. This document does spell out proper storage conditions. The excerpt below best explains why there isn’t an exact life span:
The rest of the document does explain that the chemical reaction can be re-activated if needed.