If you're looking for some startling mottling, try some Palm wax. There are 2 varieties I've used, "Q" wax for Pillars, and "F" wax for containers. The results are amazing. Use no additives, and follow the melt/pour suggestions, and the starburst patterns will form. The feathering shows up better when using dark colors, and you will have to add more color than normal. The feathering seems to lighten the color, so double your color. Fredron