I've used this technique a couple of times and it came out really well with a recent soap. I'd call it a mica-in-oil in the pot swirl, of a sort. Basically, I make a single colour batter, then drizzle mica-in-oil on the top just before I pour, leaving some to add to the top of the batter as I go along and the first batch of mica runs out.
It can leave a sticky bit of mica in your mould if you get a batch in a corner, but it's worth it for the sparkly veins through your soap.
This soap was the last cavity mould I poured while making a batch of unscented charcoal soap - I had some pink mica already mixed to do swirls on top, and on the spur of the moment I decided to do one with the mica in the soap. I'm pleased with how it came out, I wasn't sure if the charcoal would swallow it up. I think I'll do more dark soaps with bright micas through them.
It can leave a sticky bit of mica in your mould if you get a batch in a corner, but it's worth it for the sparkly veins through your soap.
This soap was the last cavity mould I poured while making a batch of unscented charcoal soap - I had some pink mica already mixed to do swirls on top, and on the spur of the moment I decided to do one with the mica in the soap. I'm pleased with how it came out, I wasn't sure if the charcoal would swallow it up. I think I'll do more dark soaps with bright micas through them.