The final step to finishing my firewall extensions were to add an additional layer of fire protection to these panels, similar to what I've done on my main firewall. It is a woven ceramic fiber textile with a thin aluminized backing. This provides a little thermal insulation but its main function is to be an additional fire barrier.
To test it, I fired up a small MAPP gas torch and heated the fiber to red heat. As you can see in the photo, it did not burn through. Moving the torch closer, it did finally burn through at an orange heat. I'm satisfied that installing it will be worthwhile. I cut the fabric to size and bonded it to the panels with red silicone RTV.
Now to re-install the main firewall and then add the extensions. I'll seal the whole thing with a tube of 3M Fire Barrier Silicone Sealant 2000+ that I bought from Aircraft Spruce. I hope it will be easier to apply than the red 3M Fire Barrier CP25WB+ that I used previously.
Regards, Neil Tucson, AZ