Originally published July 21, 2011:

Hold onto your hats, kiddos, this post is going to look an awful lot like a chemistry lesson… I had a bit of a disaster when testing out a new scent this week, & I thought you might enjoy seeing the hijinks that can occur when you don’t closely monitor your ingredients.

See these? Gorgeous, no? These are two mica blends that I whipped together as potential colorants for the upcoming August Limited Edition. I wanted something green & glittering & just a bit weird… that top one had me doing the happy dance of joy, it was so perfect.

Aaaand here’s what I found when I came back to check the test batches of soap.

Where’s my beautiful green, dammit?!

To answer that, let’s backtrack just a bit, & explore exactly what is mica… Mica is what makes my soaps & Slips sparkle, that fine shimmer that makes bars like Dead Leaves on the Dirty Ground & Sweet Cheeks shine. Mica itself is a mineral with a myraid of applications, & we use it in the bath & body industry to give our products a glittery finish. Coated with other minerals or colorants, it suddenly looks like really intense eyeshadow & makes for an amazing range of colors.

The bulk of my micas are soap-stable, meaning that I can add them to my products & not see any change in the perceived color. As I’ve found out the hard way, though, two colors in my collection are not soap stable, thanks to a pesky additive known as ferric ferrocyanide.

Perhaps more familiarly known as Prussian Blue, ferric ferrocyanide is an inorganic (i.e. synthetic), FDA-approved colorant, safe for external use. It gives an intense matte blue that’s wonderful for color blending, & it’s lovely in my Super Green & amethyst micas.

If I were using these gorgeous micas dry, I’d have nothing to worry about – the colors would stay true when brushed on the skin or, in theory, on the surface of a bar of soap. But I’m adding them into a lightly alkaline soap base, which changes the game entirely, setting the stage for a very small but very annoying chemical reaction.

Added to soap, that lovely Prussian Blue blue fades within minutes, morphing my bright green mica to a sickly yellow. Remember when I had to pull The Man in the Moon for a few months last year? Unbeknownst to me, my supplier had mis-picked my last order & instead of sending me the soap-stable lavender mica I’d been using, sent me their amethyst mica, which contains ferric ferrocyanide. Suddenly my lovely lavender & gold bars were fading to a miserable pinkish hue; it took me several months to figure out what had happened & find an alternate purple colorant. (Oh Ultramarine Violet Oxide, how I looove you!)

Meaning my funky Super Green & lovely amethyst micas will be forever gorgeous in the jar, but unmitigated failures in soap. Phooey.

So, it’s back to the drawing board for the August LE’s colorway, & I’m taping closed my jars of errant mica so I’m not tempted to use them again in soap.

Or maybe I’ll try my hand at eyeshadows…