Headliner Insulation - undercoat?

Take a gallon of good non-automotive primer (I used Glidden), mix in some of what's called "inorganic microspheres" or more commonly referred to as "glass balls", widely available at marine supply stores, and you've just made your own Lizard Skin for a fraction of the cost of the real stuff.
I used it throughout my car before applying sound deadening material from B-Quiet.