I learned something new recently after teaching a class at The Nova Studio. (That’s the best part of teaching: learning along the way.)
While I’ve tried out lots of natural ingredients to color cold process soap (ahem, I even wrote an eBook on the subject), I haven’t done a lot of coloring with more than one color in bar at the same time. But in this class, I decided to demonstrate a vertical layer with a swirl using turmeric and madder root to color each half of the batch.
So wasn’t it a lovely surprise to discover that turmeric bleeds in soap?! That is to say that the color doesn’t stay where you place it in the bar: it migrates and blends into the neighboring soap making the border between the two colors fuzzy. 
Compare this result with other bars I’ve made using the same technique but using other colorants that don’t bleed into each other. See how crisp the borders are? This soap was colored with micas. Very different.
I suspect that it’s the turmeric that’s migrating because I have made a two-colored soap with madder root before. In that case the other part was colored with clay and there was no color migration. 
But it could be that turmeric and madder root together act differently than clay and madder root. More testing is in order!
Have you ever discovered something about soapmaking by chance?
Make Me Some Soap... 
Turmeric does migrate, and the yellow color eventually disappears. I am not sure exactly how many months the color lasts. I have a turmeric and charcoal soap that’s nearly a year old. I kept it wrapped with paper. I opened it last week and the soap is just black and white now. Tomato also migrates. I had a 3-layered soap – the bottom colored orange with tomato paste, the middle with ground rosemary and a pinch of green oxide, and the top with TD. Within a few weeks, the orange color had migrated from the bottom all the way to the top of the soap.
Thanks for sharing your experiences, soapjam! We just have to learn and accommodate, don’t we? 🙂
I feel like I discover something about Soapmaking every day (which makes us all better soapers, right?) =) I think your soap looks fantastic and I can barely see any color migration at all =)
Thanks, Anne-Marie! I could never get bored with soapmaking: there’s always new things to try. 🙂
It may not have been what you were going for, but the batch still looks fabulous!
This soap is beautiful!
– KW
http://musthaveboxes.com
The turmeric and madder root make for a very pretty textured look in your soap. I really like how it looks speckled. Can’t wait to try the turmeric in one of my soaps!
this soap is nice