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"Common sense" question
  • tsunamino
    Being a sociologist, I'm always skeptical about what we consider to be "common sense". Common sense means that we should know what it is because everyone knows that it's true, but it may not always be true. For example, it used to be "common sense" that Native Americans and blacks were just simply genetically inferior to everyone, or women simply didn't have the brain capacity to vote.

    With cosmetics, it seems to be common sense to throw out a mascara after 3 months or a foundation after 6. Is this true or is a marketing scheme to get us to buy more products? I usually toss out stuff if they smell bad, but is there a set deadline of when you should throw something out? Does it matter if a product is in a jar or a pump? Does a pump make the product more "hygienic" or does it just play off today's Lysol culture?

    I realize this may all sound like common sense questions, but sometimes I feel it is important to reevaluate our assumptions and see if they are true in the first place!
  • Left BrainLeft Brain
    We've written a few posts about the expiry dates of cosmetics although I don't think we've specifically answered your question.  Check out this post and the realted ones to see if it helps you.
    http://tinyurl.com/dfntnv
    Your stratgey of throwing them out when they smell bad is a good one.  Truthfully, there is not a set deadline for when you should throw things away.  In the cosmetic business when we are creating products, we do a thing called Stability testing.  Products are tested for anywhere from 8 weeks to over 1 year.  Usually, you should throw away anything that is over a year old. 
    Yes, pump products are more hygenic (at least in theory).  Jar products have more chance of being contaminated.  To offset this, cosmetic chemists put more preservative in them.
  • tsunamino
    Thank you for answering my question! I have another question. I was told by an esthetician that when a product with a metal lid gets a little rusty, it means that the bacteria that has built up from the jar is growing on the lid and it's time to throw it away. Is this true?
  • Left BrainLeft Brain
    While the advice to throw away a product that has a rusty lid might not be bad, the reason given is wrong.
    Rust is not caused by bacteria from the product.  It is caused by a combination of water + oxygen.  Bacteria has nothing to do with it. 
    But throwing it away is a good idea because that means it's probably old and the container might be rusted on the inside.
  • tsunamino
    That sounds more probable, since bacteria doesn't cause rust. Thank you for taking the time to answer my question.
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