How to paint fading colours?
If you are painting a realistically sized sword, then paint it all white until that is opaque and dry. Come back with commercial spray paint and spray on the purple part, letting the purple get paler as it blends into the white. If there are other colors like yellow and orange or red, then spray the yellow on first, the orange second, and the purple last letting each layer dry thoroughly before spraying on the next color. Test your spraying skills on a scrap piece of white painted paper first. Good luck!! ; ) note: use matte or flat spray paint as it will create the blended look much better. When all the coloring is done and very dry, you can spray on a glossy clear finish coat.
