Heat temper/discoloration effect, How to

A lot of people are asking me how I did the heat effect on the Mechanicum Knight's cannon that i just finished.  Well here is a quick description.

Mechanicum Knight Finished,

One more Freeblade knight and then some Word Bearers I think

Down and Dirty Mechanicum War Stripes

Listening to Mechanicum right now on Audio Book and have the Red Planet Bug BAD AGAIN!.  Decided to work on a Knight today.

Death Guard Fell Blade Tank FINISHED!

I have been working on this one for a year and finally got confident enough to start the heavy weathering.  I have been experimenting on smaller "cheaper" models.  This baby is a center piece in my army, love this model.