Character wiping fog off a mirror using dynamic paint I've been making a scene where a character wipes fog and water droplets off a mirror to reflect themselves. I made a dynamic paint sequence using the character as the brush, but i cant work out the way to make the material so the paint brush paints a mirror texture on and leaves the fog texture. I can only get it to either paint the fog on or leave a black background. 
 How can i make the brush work as a layer on top of the original water droplets texture?
So using a LOG math node at 0.9 with a colour ramp into the factor did the trick. If anyone knows exactly why I'd love to know.