When’s a Chemical not a Chemical?

Chemicals surround us.  They’re in the food we eat, the drinks we drink, and the air we breathe.  Our entire bodies are nothing but chemical processes.

A couple of weeks ago, the girls and I were in a shop where there was a sign that read, “SoapsChemical free!”  Mary, my older daughter, quipped, “So they left out the lye?”  I returned, “And the water, the oils, and the fragrance.”  While the “chemical free” sign may entice unwary consumers, it really felt like the creator of the sign is , at best, ignorant of what, exactly, soapmaking is, and at worst, willfully practicing deceptive business practices (given that artificially scented soaps are labeled “all natural” and have “essential oil” on the label, I lean towards the latter).

Unit cell, spacefill model of sodium hydroxide
Unit cell, spacefill model of sodium hydroxide (Photo credit: Wikipedia)

Soapmaking is chemistry.  The very idea of this amuses me greatly, given how hard I struggled in high school and college chemistry.  Sodium hydroxide (lye) mixes with water (usually), and that mixture, in turn, is added to oils in liquid form; they are then emulsified together, either by stirring or blending, before having additives added to the raw soap and being poured into a mould.  The magic happens here as the mixture creates heat internally which causes the whole thing to gel.  This is a super-cool exothermic reaction wherein the beautifully swirled and designed raw soap changes color, smells funky, and looks like really runny, chunky petroleum jelly.  It looks like the soap is a ruined mess at this point, but as the hours pass, the soap cools down, revealing the amazing colors and patterns once more.  That process is called saponification.  Actually, the gel phase is the heart of saponification, a chemical reaction that starts where the lye mixture meets the oils and ends formally at the end of the curing time.  While gel phase only lasts 12-36 hours, saponification can last weeks.

Chemicals coming together to create a chemical reaction and cause a chemical change.  Sodium hydroxide is a chemical – NaOH.  So is water – H2O.  And oils are as well – the formula for olive oil is C52H96O6.  You can separate sodium hydroxide from water, allowing water to evaporate and lye crystals to form (9th grade science fair project).  However, once that lye mixture combines with the oils, there’s no going back.  The change is permanent and irrevocable.  This is the hallmark of chemical change – a chemical reaction produces a change that cannot be reversed.  Ahhh chemistry.

Well, you may argue, the creator of the “chemical free” sign means no harmful chemicals.  What makes a chemical harmful?  How natural it is?  Cyanide is a naturally occurring chemical element, but I think we can agree it’s very harmful.  Sodium hydroxide is a chemical that can be produced from natural processes (pouring water through ashes), and it doesn’t take much – relatively speaking – to dissolve a 300-pound body.  Yet, it sometimes appears in cosmetics and pickles.  Dihydrogen monoxide!  There’s a “safe” chemical.  In fact, I add it to every soap, lotion, and cream that I make.  Yet, more people die of exposure to DHMO each year than from exposure to all other chemicals combined!  Obviously, what makes a chemical “safe” or not is how it’s used and how much is used.  A little NaOH or a little salt isn’t harmful, but an abundance of either can cause sickness, death, or complete disintegration.

Bottom line, there is no “chemical-free” soap, because all components of soap are chemicals, and the resulting product is soap and glycerin.  Artisan made soaps are proof that there is better living through chemicals.