Chuck Trafagander Walks Through Creating Burnt Wood in His New Substance Designer Tutorial for Beginners.
Get Learnt is a new outlet for tutorials by Chuck Trafagander, who posts both beginner and more advanced topics on substance designer. He also has a series of Ultimate materials that cover the basics in detail as well as walk-throughs with Unity 3D Engine tools such as Painterly Painting Tools or Cycles lighting system.
He started with a simple wood material, but then he added flame effects to create an awesome burnt-out effect. Watch the tutorial for more information on how you can do this in Designer!