Strawcat (strawcat) wrote,

The Problem of Unspecified Purity

Dear Ivory,

I have always wondered how the consumer is supposed to interpret the popular slogan that your soap is 99 44/100% pure. While many people will be impressed by seemingly high numbers that do not appear to designate anything specific, the more conscientious consumer will have to ask, "99 44/100% pure what?" The most intuitive assumption is that Ivory soap is 99 44/100% pure soap. If 99 44/100% = 99.44% (I'm not sure; I've never seen a percentage expressed in that way), this means that Ivory's soap is made up of 0.56% non-soap. In other words, Ivory soap contains 5600 ppm impurities. This may not mean anything at first, but if you consider that tap water only contains 150-500 ppm impurities, the advertisement of unspecified purity appears result in the opposite to the intended effect.

If I were choosing between brands of vanilla ice cream, I would be a little concerned if one brand claimed it was 99.44% pure vanilla ice cream, because then I would have to wonder, "Just what kind of impurities would I be putting into my system if I were to eat this stuff?" since the ingredients of the ice cream would compose 99.44% of the product, which would be listed, and the 5600 ppm of mysterious unknowns may be unlisted. I would feel safer choosing the "100% pure vanilla" even if they're not particularly rigorous about defining their terms. I would also prefer a brand that made no claims at all about purity.

But this is probably not what you mean. What you probably mean is that your product contains 99 44/100% active ingredients (or cleaning power) and the remainder are things like fragrance. However, this does not seem to be the most obvious definition of purity, and most people who seriously contemplate the matter of unspecific purity would sooner jump to the previous, unsavory conclusions.
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