Debra,
I tried this just like you explained it and the swirl came out beautifully! My coloring, however left a lot to be desired. I was trying to make it pink and burgundy with pomegranate scent. I colored my separated soaps and when I added the FO, it turned it very yellow. I guess I should have added more UM Pink to the pink part because it came out creamy beige. The burgundy, colored with blue shade of red oxide ended up a little burgundy, but mostly brown. So my soap looks like chocolate and vanilla. Strangely, it seems to smell more like chocolate than pomegranate, too. Maybe it's all in my head! LOL
Anyway the swirl is fabulous and the prettiest swirl I've ever done, so thanks for sharing your technique!