I found this great little website: Leaftradingpost.com. It's not a soap supply page, they sell some really neat natural things like antlers, sheepskin, beeswax and natural dyes. Their prices are very reasonable and the service is excellent. I ordered some dyes and a bit of mordant (that's to use in fabric dyeing should I get bored with soaps - fat chance) and one of them was madder root.
Madder root is soluble in water and although I had seen somewhere a suggestion to use madder root powder infused in oil, I had more coarse chunks and put them into the lye solution. It turned a lovely purplish red. I saw somewhere that it was smart to steep it in the lye solution overnight, but I was in a hurry.
Madder root has very many colouring agents ranging from orange to blue-red.
I probably should have steeped it overnight because the result was a VERY delicate pink. But pretty all the same. I put some madder in a jar with some lye and put it in the fridge for using next time. Maybe I'll get a darker pink.
I made up a new recipe that I thought would be gentle and suitable for a pink soap:
Coconut oil - 175 g / 6.2 oz
Lard - 175 g / 6.2 oz
Grapeseed oil - 104 g / 3.7 oz
Almond oil - 102 g / 3.6 oz
Apricot kernel oil - 74 g / 2.6 oz
Sunflower oil - 70 g 2.5 oz
Lye - 98 g / 3.5 oz
Water - 266 g /9.4 oz
That should be about 5% SF, but as always check in a lye calculator.
So about 1 tbsp madder root into the hot lye solution which is then strained into the oils.
For fragrance I used a blend of clary sage, geranium and lemongrass EO. Smells wonderful. The resulting soap was a nice consistency, fairly hard for me and it cut nicely. It's still curing, so I'll have to wait a little while to test it.
Update: The colour faded and was gone after about 9 months. But this is still one of my favorite soaps.