In last year’s soap making, layering indigo and white in one soap seems to have been the least successful, especially when the combination was an insert. I started out pouring a batch in layers (2, blue and white; or 5 blue and white 3 and 2). Later on I would pour a fraction of a recipe in blue (or white) let it set, and then put it in the mold a day or week later, and pour another fraction of the batter (white or blue) around it. Months later, it was this insert technique that seemed to have the blue leaching into the white, turning the edge of the white a reddish color. When I poured the layers in one batch, this did not seem to be a problem save for one batch of three layers of blue to light blue, where the lighter blue went reddish. The recipe is the same for each technique (from layer to layer). So does using an insert do something that changes the interaction between layers that allows leaching of blue into white?