Larry,
I spun it on the lathe. There are a lot of variables a play in this sort of thing.
How thick of a coat of the paint is applied
How viscous is the paint
What is the base the paint is applied to (gloss lacquer to porous wood)
What RPM
What size piece
In my case, I used a base coat of gloss black rattle-can spray-paint. The colors are Jo Sonja iridescent paints. Against a black background they shimmer and change intensity depending on viewing angle. With the piece held in a chuck, I quickly applied red, purple and gold in concentric rings. I then put a box over the piece so that any paint flung off would end up on the inside of the box and not all over the place. I then turned on the lathe at around 600 RPM (started off at 300 RPM but no paint movement) for a few seconds at a time to see how it was going.
Starting off slow and short duration is a good idea as you can always spin it some more but can't un-spin (not even if your lathe has reverse)
I am going to experiment with some hard board painted black to get a better feel for the Jo Sonja colors. I made up some 8" squares which is a fairly typical size piece for me.
I think one needs to stabilize some of the variables to learn this technique. I'll select a consistent type of gloss black base coat, stick with the Jo Sonja colors and a nominal 8" piece. I can then experiment with application of the colors and speed / duration f spinning.
I tried just hardboard with no gloss black. The colors looked great, but the hardboard soaks up moisture so fast that it dried the colors almost instantly, and they would not run when I ran the lathe up to over 1000 RPM.