Colloidal silver can definitely expire. Generally colloidal silver has the tendency to lose its effectiveness thus emphasizing its expiration. A lot of bottles of Colloidal Silver have their expiry date clearly put on the bottle.
Colloidal silver is usually kept within an electronics magnetic field. Some of these electronics are microwaves and any other electrical appliance that can store it.
The way a colloidal silver charges up electrically can be inhibited by its magnetic field. Of course, products have its expiration date, the exact way it applies to Colloidal silver.
It comes into expiration rapidly when colloidal silver oxidizes exactly right in the presence of the gas oxygen.
Right before purchase please check its expiry date because it can definitely expire just as any product that has been manufactured for a long time and has reached its expiry date