Flour tortillas are my preferred canvas.  I like the way they take on a warm shade of brown when you hit them with the heat gun.

But the flour tortilla can be a capricious mistress.  She can bend and twist as you warm her up, and her once supple flesh can become brittle and fragile.  You are not in total control of the process.  She is.  Sometimes she  makes herself her look really great, and sometimes she wrecks herself, just to piss you off.

This demonstration illustrates what I mean... 

I started out with a batch of browning sauce, mixed with burnt umber acrylic paint. 

But I approached this painting is a little differently from my usual method.  I didn't just paint the dark areas, I tried to create more of a sense of depth by scrumbling the brush over the surface of the tortilla.  I put just a little browning sauce on the brush, then lightly dragged it over the tortilla.  This helped model the volume of the head and ears.

I also painted around the edge of the tortilla.  This helped frame and define the image. 

Man, I just read that paragraph.  I sound like an art teacher.