Eli5: How come hand sanitizer has an expiration date? What exactly happens once it goes past it?
In: Chemistry
The sanitizer and the bottles are not completely chemically stable. There are some chemical reactions happening athough they are slow. This means that the chemicals change over time. For example the plastic bottles may slowly dissolve into the liquid. The chemicals in the liquid itself might react to each other turning into other chemicals. A big problem can be that the alcohol reacts with oxygen or other oxidizers and turns into vinigar. The chemicals might also be emultifications which will slowly seperate over time so you get different layers with different chemicals. A handfull of gel will do nothing if the alcohol have seperated into a seperate layer.
It becomes less effective. Hand sanitiser works best the higher the alcohol content. Now, of the ingredients in hand sanitiser alcohol easily evaporates. This means over time as the alcohol in the hand sanitiser evaporates the less effective it becomes. You may think that you’re properly sanitising your hands but you’re not.
LPT: Expired and low-alcohol content hand sanitizers work exceptionally well for cleaning white boards.
Also: the expiration date is set somewhat arbitrarily, and marks the end of the period of time tested. The test period is generally selected to account for storage time required for manufacturing and distribution, in a case like hand sanitizer, there’s probably some consideration of the typical “lifespan” of a container in the consumer’s possession. It would also assume recommended storage conditions; container closed, at room temperature.
Exceeding the expiration date simply means no data exists to support its continued efficacy, and it’s likely to be good well beyond that date.
So what about storing it in the car? A very hot car in the summer.
I invented Germ-X so I can weigh in here. It is an OTC drug and it is required to have an expiration date per the FDA to which it must by registered by law. When I developed it it went through three months of stability testing which gave it a shelf life of two years. Anything beyond that the product loses efficacy as the alcohol will very slowly evaporate. Some of these comments are pretty accurate and a couple are pretty amusing.
Also worth noting that even if it “theoretically” could last decades, centuries or forever most companies will still slap an expiration on.
Because its just hard to prove it lasts that long, but it’s easier to prove a few years. (Similar to killing 99.99% rather than 100% on antibacterial stuff)
Another reason could just be profit, if your not charging a premium for the long life then just chuck an expiration on so people replace it.
I thought it had to do with the plastic bottles. Bottled water has a shelf life of 2 years. Not the water itself but the plastic bottle. Plastic starts to degrade and contaminates the contents of the container. I thought this was the same reason anything in a plastic bottle has an expiration date.
The manufacturer becomes disappointed in you for being a bad consumer and not purchasing their product as frequently as they’d desire.
if you had a 10 year old bottle of sanitizer, the alcohol would probably have escaped through imperfections in the seal and the porousness of plastic.
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