- How long does alum powder last? The precise answer depends to a large extent on storage conditions - to maximize the shelf life of alum powder store in a cool, dark cupboard, away from direct heat or sunlight.
How long does alum powder last at room temperature? Properly stored, alum powder will generally stay at best quality for about 2 to 3 years.
To maximize the shelf life of alum powder purchased in bulk, store in containers with tight-fitting lids.
Is alum powder safe to use after the "expiration" date on the package? Yes, provided it is properly stored and the package is undamaged - commercially packaged alum powder will typically carry a "Best By," "Best if Used By," "Best Before," or "Best When Used By" date but this is not a safety date, it is the manufacturer's estimate of how long the alum powder will remain at peak quality.
Does alum powder ever spoil? No, commercially packaged alum powder does not spoil, but it will start to lose effectiveness over time - the storage time shown is for best quality only.
Sources: For details about data sources used for food storage information, please click here