Hi chuck. U will have to using swirl brush on dry media, do not use any water for the acrylic and go swirl the brush into the canvas repeatedly with low painting method (in digital u are going to add 10% opacity) and less color mix. The same way for painting sky clouds I guess.
It's hard to tell or explain in words, I hope you'll understand but let's see if I could snapshot my demo in free time.
:: Digital Shapeshifter ::