This is an undeniable fact. It is also a 'truth' worth taking a good look at from the backside, because it rests at the heart of the problem plaguing contemporary invention/innovation -- projecting possibilities into the unknown.
It is very hard for most of us to imagine something that doesn't yet exist. You can think, 'boy, do I wish a had an X that did Y and maybe Z,' but knowing how to proceed from there can be a stumbling block. Once upon a time, there were three major routes to invention: the home garage shop, public funding to universities, and commercial R&D. Today, all are threatened. Few of us can do much about the latter two, but any of us can be part of the revitalization of home invention. That's where 'impurities' come in.
For most of history, inventors (usually amateurs) had no choice but to use inconsistent ingredients, and damn good thing that. The odd 'contaminant' that changed a formula was the freebie from the gods that pointed the way into the unknown and, as of yet, unachieved. (I've always loved that quote of Dr. J and Mr. H) After the 'Eureka!', they could go in and hopefully isolate the new ingredient, but the initial impurity was the magic key to discovery.
For those of us trying to reinvent old emulsions, ingredients that aren't of the highest purity are absolute gifts - if you are willing to be an old-fashioned amateur scientist, embracing the occasional dead end or spectacular failure in the pursuit of spectacular success. A perfect example is my favorite recipe for warm-toned emulsion. I replaced lab grade NaCl with evaporated sea salt (albeit a brand that promises it's from the cleanest waters in the Pacific Ocean) Whatever odd chloride is in that salt, in undoubtedly miniscule amounts, changed the character and improved the quality of the emulsion.
It is a profound philosophical question for scientists, both amateur and professional: should an unforeseen, and therefore by definition unplanned, consequence be considered a 'desired reaction'.
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