The CP recipe is fairly basic. 20% olive oil, 20% coconut oil, 20% sunflower oil, 20% palm oil, 10% cocoa butter, 10% castor oil. Soap at room temp then heat in the at 170F for 20 minutes. Then cool down. The yellow soap is colored with turmeric and the right is colored with Moroccan clay. Interestingly, if I don't add any colorant this line doesn't develop and the line on the Moroccan clay isn't as noticeable. This makes me think that maybe it has something to do with the heating of botanicals for colorants. I am trying to use natural colorants but find them difficult to work with because changes in concentration, temperature, etc will yield a different color outcome.